Lost top end power in 88 Cherokee 4.0.
 

Ok, I am on a fishing expedition for likely things to check.

Our 88 Cherokee with the 4.0 has lost power above half throttle. It
goes fine up to that point, then just bogs, no matter what gear it is
in. It has been neglected for 4 years as far as tuning goes due to me
not being up to it.

I first changed out the 'very' dirty distributor cap and rotor which
made starting 'much' faster and smoother.

I then changed the gas filter because it was once again rusted to the
rot point after about 8 years.

Air filter is new.

I cleaned the connections on the TPS and IAC and verified the TPS
doesn't have any 'dead' spots with my meter.

I cleaned the CPS and coil connections also.

No joy on any of that.

I have been having some cold idle issues and have been thinking on
cleaning the IAC, but don't know if that will have a top end effect or not.

I am also thinking on unplugging the EGR just to make sure it isn't
blown vacuum wise because it only bogs under throttle when things like
the EGR are active.

Any other ideas?

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Re: Lost top end power in 88 Cherokee 4.0.
 

> Any other ideas?
>

Did you open up the old fuel filter, or blow it backwards into a can to
inspect for dirt or sparkles that could indicate a pump dying?
I would run a fuel pressure test, and then a cat pressure test.
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty

Re: Lost top end power in 88 Cherokee 4.0.
 

> Any other ideas?
>

Did you open up the old fuel filter, or blow it backwards into a can to
inspect for dirt or sparkles that could indicate a pump dying?
I would run a fuel pressure test, and then a cat pressure test.
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty

Re: Lost top end power in 88 Cherokee 4.0.
 

> Any other ideas?
>

Did you open up the old fuel filter, or blow it backwards into a can to
inspect for dirt or sparkles that could indicate a pump dying?
I would run a fuel pressure test, and then a cat pressure test.
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty

Re: Lost top end power in 88 Cherokee 4.0.
 

> Any other ideas?
>

Did you open up the old fuel filter, or blow it backwards into a can to
inspect for dirt or sparkles that could indicate a pump dying?
I would run a fuel pressure test, and then a cat pressure test.
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty

Re: Lost top end power in 88 Cherokee 4.0.
 

Stupendous Man wrote:
>> Any other ideas?
>>
>
> Did you open up the old fuel filter, or blow it backwards into a can to
> inspect for dirt or sparkles that could indicate a pump dying?
> I would run a fuel pressure test, and then a cat pressure test.

Yes I did blow out the filter and besides being a bit hard to blow
through, it appeared ok. Rotted pretty bad though.

I have no cat to check, well there has been nothing 'in' the cat since
before I bought it and it still passed emissions great.

I have no real way to check for fuel pressure I don't think unless one
of my old compression testers could be converted??

The miss is pretty consistent.

Thanks,

Mike

Re: Lost top end power in 88 Cherokee 4.0.
 

Stupendous Man wrote:
>> Any other ideas?
>>
>
> Did you open up the old fuel filter, or blow it backwards into a can to
> inspect for dirt or sparkles that could indicate a pump dying?
> I would run a fuel pressure test, and then a cat pressure test.

Yes I did blow out the filter and besides being a bit hard to blow
through, it appeared ok. Rotted pretty bad though.

I have no cat to check, well there has been nothing 'in' the cat since
before I bought it and it still passed emissions great.

I have no real way to check for fuel pressure I don't think unless one
of my old compression testers could be converted??

The miss is pretty consistent.

Thanks,

Mike

Re: Lost top end power in 88 Cherokee 4.0.
 

Stupendous Man wrote:
>> Any other ideas?
>>
>
> Did you open up the old fuel filter, or blow it backwards into a can to
> inspect for dirt or sparkles that could indicate a pump dying?
> I would run a fuel pressure test, and then a cat pressure test.

Yes I did blow out the filter and besides being a bit hard to blow
through, it appeared ok. Rotted pretty bad though.

I have no cat to check, well there has been nothing 'in' the cat since
before I bought it and it still passed emissions great.

I have no real way to check for fuel pressure I don't think unless one
of my old compression testers could be converted??

The miss is pretty consistent.

Thanks,

Mike

Re: Lost top end power in 88 Cherokee 4.0.
 

Stupendous Man wrote:
>> Any other ideas?
>>
>
> Did you open up the old fuel filter, or blow it backwards into a can to
> inspect for dirt or sparkles that could indicate a pump dying?
> I would run a fuel pressure test, and then a cat pressure test.

Yes I did blow out the filter and besides being a bit hard to blow
through, it appeared ok. Rotted pretty bad though.

I have no cat to check, well there has been nothing 'in' the cat since
before I bought it and it still passed emissions great.

I have no real way to check for fuel pressure I don't think unless one
of my old compression testers could be converted??

The miss is pretty consistent.

Thanks,

Mike

Re: Lost top end power in 88 Cherokee 4.0.
 

Plug wires can do this, but they will usually give you some backfiring along
with the bogging down.

Earle

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4659a194$0$3020$9a6e19ea@unlimited.newshostin g.com...
> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
> goes fine up to that point, then just bogs, no matter what gear it is
> in. It has been neglected for 4 years as far as tuning goes due to me
> not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor which
> made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to the
> rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end effect or
not.
>
> I am also thinking on unplugging the EGR just to make sure it isn't
> blown vacuum wise because it only bogs under throttle when things like
> the EGR are active.
>
> Any other ideas?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)

Re: Lost top end power in 88 Cherokee 4.0.
 

Plug wires can do this, but they will usually give you some backfiring along
with the bogging down.

Earle

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4659a194$0$3020$9a6e19ea@unlimited.newshostin g.com...
> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
> goes fine up to that point, then just bogs, no matter what gear it is
> in. It has been neglected for 4 years as far as tuning goes due to me
> not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor which
> made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to the
> rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end effect or
not.
>
> I am also thinking on unplugging the EGR just to make sure it isn't
> blown vacuum wise because it only bogs under throttle when things like
> the EGR are active.
>
> Any other ideas?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)

Re: Lost top end power in 88 Cherokee 4.0.
 

Plug wires can do this, but they will usually give you some backfiring along
with the bogging down.

Earle

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4659a194$0$3020$9a6e19ea@unlimited.newshostin g.com...
> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
> goes fine up to that point, then just bogs, no matter what gear it is
> in. It has been neglected for 4 years as far as tuning goes due to me
> not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor which
> made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to the
> rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end effect or
not.
>
> I am also thinking on unplugging the EGR just to make sure it isn't
> blown vacuum wise because it only bogs under throttle when things like
> the EGR are active.
>
> Any other ideas?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)

Re: Lost top end power in 88 Cherokee 4.0.
 

Plug wires can do this, but they will usually give you some backfiring along
with the bogging down.

Earle

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4659a194$0$3020$9a6e19ea@unlimited.newshostin g.com...
> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
> goes fine up to that point, then just bogs, no matter what gear it is
> in. It has been neglected for 4 years as far as tuning goes due to me
> not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor which
> made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to the
> rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end effect or
not.
>
> I am also thinking on unplugging the EGR just to make sure it isn't
> blown vacuum wise because it only bogs under throttle when things like
> the EGR are active.
>
> Any other ideas?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)

Re: Lost top end power in 88 Cherokee 4.0.
 

Mike Romain <romainm@sympatico.ca> wrote:

> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle.
> It goes fine up to that point, then just bogs, no matter what gear
> it is in. It has been neglected for 4 years as far as tuning goes
> due to me not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor
> which made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to
> the rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end
> effect or not.
>
> I am also thinking on unplugging the EGR just to make sure it
> isn't blown vacuum wise because it only bogs under throttle when
> things like the EGR are active.
>
> Any other ideas?

Look at simple things, it sounds like it might be starving for fuel?
Test fuel pressure and flow, consider clogged catalytic converter, look
for a stopped up fuel vent. You changed the fuel filter, is there
possibly another one, maybe in the tank?





--
XS11E, Killing all posts from Google Groups
The Usenet Improvement Project: http://blinkynet.net/comp/uip5.html

Re: Lost top end power in 88 Cherokee 4.0.
 

Mike Romain <romainm@sympatico.ca> wrote:

> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle.
> It goes fine up to that point, then just bogs, no matter what gear
> it is in. It has been neglected for 4 years as far as tuning goes
> due to me not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor
> which made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to
> the rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end
> effect or not.
>
> I am also thinking on unplugging the EGR just to make sure it
> isn't blown vacuum wise because it only bogs under throttle when
> things like the EGR are active.
>
> Any other ideas?

Look at simple things, it sounds like it might be starving for fuel?
Test fuel pressure and flow, consider clogged catalytic converter, look
for a stopped up fuel vent. You changed the fuel filter, is there
possibly another one, maybe in the tank?





--
XS11E, Killing all posts from Google Groups
The Usenet Improvement Project: http://blinkynet.net/comp/uip5.html

Re: Lost top end power in 88 Cherokee 4.0.
 

Mike Romain <romainm@sympatico.ca> wrote:

> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle.
> It goes fine up to that point, then just bogs, no matter what gear
> it is in. It has been neglected for 4 years as far as tuning goes
> due to me not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor
> which made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to
> the rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end
> effect or not.
>
> I am also thinking on unplugging the EGR just to make sure it
> isn't blown vacuum wise because it only bogs under throttle when
> things like the EGR are active.
>
> Any other ideas?

Look at simple things, it sounds like it might be starving for fuel?
Test fuel pressure and flow, consider clogged catalytic converter, look
for a stopped up fuel vent. You changed the fuel filter, is there
possibly another one, maybe in the tank?





--
XS11E, Killing all posts from Google Groups
The Usenet Improvement Project: http://blinkynet.net/comp/uip5.html

Re: Lost top end power in 88 Cherokee 4.0.
 

Mike Romain <romainm@sympatico.ca> wrote:

> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle.
> It goes fine up to that point, then just bogs, no matter what gear
> it is in. It has been neglected for 4 years as far as tuning goes
> due to me not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor
> which made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to
> the rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end
> effect or not.
>
> I am also thinking on unplugging the EGR just to make sure it
> isn't blown vacuum wise because it only bogs under throttle when
> things like the EGR are active.
>
> Any other ideas?

Look at simple things, it sounds like it might be starving for fuel?
Test fuel pressure and flow, consider clogged catalytic converter, look
for a stopped up fuel vent. You changed the fuel filter, is there
possibly another one, maybe in the tank?





--
XS11E, Killing all posts from Google Groups
The Usenet Improvement Project: http://blinkynet.net/comp/uip5.html

Re: Lost top end power in 88 Cherokee 4.0.
 

On May 27, 11:20 am, Mike Romain <roma...@sympatico.ca> wrote:
> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
> goes fine up to that point, then just bogs, no matter what gear it is
> in. It has been neglected for 4 years as far as tuning goes due to me
> not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor which
> made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to the
> rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end effect or not.
>
> I am also thinking on unplugging the EGR just to make sure it isn't
> blown vacuum wise because it only bogs under throttle when things like
> the EGR are active.
>
> Any other ideas?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590
> (More Off Road album links at bottom of the view page)

What does exactly "then just bogs" mean? The Jeep does not go any
faster, or it stalls and stops? What precise noises/knocks and
symptoms, etc?

On idle, what happens if you press accelerator until above half
throttle? Is there a loss of power?

If the fuel pressure is low, the engine can run fine upto a point,
until the demand for fuel exceeds the supply due to low pressure.

Re: Lost top end power in 88 Cherokee 4.0.
 

On May 27, 11:20 am, Mike Romain <roma...@sympatico.ca> wrote:
> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
> goes fine up to that point, then just bogs, no matter what gear it is
> in. It has been neglected for 4 years as far as tuning goes due to me
> not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor which
> made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to the
> rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end effect or not.
>
> I am also thinking on unplugging the EGR just to make sure it isn't
> blown vacuum wise because it only bogs under throttle when things like
> the EGR are active.
>
> Any other ideas?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590
> (More Off Road album links at bottom of the view page)

What does exactly "then just bogs" mean? The Jeep does not go any
faster, or it stalls and stops? What precise noises/knocks and
symptoms, etc?

On idle, what happens if you press accelerator until above half
throttle? Is there a loss of power?

If the fuel pressure is low, the engine can run fine upto a point,
until the demand for fuel exceeds the supply due to low pressure.

Re: Lost top end power in 88 Cherokee 4.0.
 

On May 27, 11:20 am, Mike Romain <roma...@sympatico.ca> wrote:
> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
> goes fine up to that point, then just bogs, no matter what gear it is
> in. It has been neglected for 4 years as far as tuning goes due to me
> not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor which
> made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to the
> rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end effect or not.
>
> I am also thinking on unplugging the EGR just to make sure it isn't
> blown vacuum wise because it only bogs under throttle when things like
> the EGR are active.
>
> Any other ideas?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590
> (More Off Road album links at bottom of the view page)

What does exactly "then just bogs" mean? The Jeep does not go any
faster, or it stalls and stops? What precise noises/knocks and
symptoms, etc?

On idle, what happens if you press accelerator until above half
throttle? Is there a loss of power?

If the fuel pressure is low, the engine can run fine upto a point,
until the demand for fuel exceeds the supply due to low pressure.

Re: Lost top end power in 88 Cherokee 4.0.
 

On May 27, 11:20 am, Mike Romain <roma...@sympatico.ca> wrote:
> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
> goes fine up to that point, then just bogs, no matter what gear it is
> in. It has been neglected for 4 years as far as tuning goes due to me
> not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor which
> made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to the
> rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end effect or not.
>
> I am also thinking on unplugging the EGR just to make sure it isn't
> blown vacuum wise because it only bogs under throttle when things like
> the EGR are active.
>
> Any other ideas?
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590
> (More Off Road album links at bottom of the view page)

What does exactly "then just bogs" mean? The Jeep does not go any
faster, or it stalls and stops? What precise noises/knocks and
symptoms, etc?

On idle, what happens if you press accelerator until above half
throttle? Is there a loss of power?

If the fuel pressure is low, the engine can run fine upto a point,
until the demand for fuel exceeds the supply due to low pressure.

Re: Lost top end power in 88 Cherokee 4.0.
 

stilllearning wrote:
> On May 27, 11:20 am, Mike Romain <roma...@sympatico.ca> wrote:
>> Ok, I am on a fishing expedition for likely things to check.
>>
>> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
>> goes fine up to that point, then just bogs, no matter what gear it is
>> in. It has been neglected for 4 years as far as tuning goes due to me
>> not being up to it.
>>
>> I first changed out the 'very' dirty distributor cap and rotor which
>> made starting 'much' faster and smoother.
>>
>> I then changed the gas filter because it was once again rusted to the
>> rot point after about 8 years.
>>
>> Air filter is new.
>>
>> I cleaned the connections on the TPS and IAC and verified the TPS
>> doesn't have any 'dead' spots with my meter.
>>
>> I cleaned the CPS and coil connections also.
>>
>> No joy on any of that.
>>
>> I have been having some cold idle issues and have been thinking on
>> cleaning the IAC, but don't know if that will have a top end effect or not.
>>
>> I am also thinking on unplugging the EGR just to make sure it isn't
>> blown vacuum wise because it only bogs under throttle when things like
>> the EGR are active.
>>
>> Any other ideas?
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's
>> Canadian Off Road Trips Photos: Non members can still view!
>> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590
>> (More Off Road album links at bottom of the view page)
>
> What does exactly "then just bogs" mean? The Jeep does not go any
> faster, or it stalls and stops? What precise noises/knocks and
> symptoms, etc?

Stalls and stops and sputters until the gas pedal is let up on.

No backfires.

EGR now unplugged.


>
> On idle, what happens if you press accelerator until above half
> throttle? Is there a loss of power?

If I go fast on the pedal, there is a dead spot. No load and smooth
pedal seems to work.

>
> If the fuel pressure is low, the engine can run fine upto a point,
> until the demand for fuel exceeds the supply due to low pressure.
>

I knew there was a reason that filter was the second thing I went after.
;-) I don't have a pressure gauge other than a compression gauge though.

I also have verified the coil wire still has a connection with the ohm
meter. It is a bit higher per foot in resistance than the plug wires,
but only a bit, .7K vs .5K. Hmm the others I have around seem the same
too....

I made sure the main power had good connections also.

Mike

Re: Lost top end power in 88 Cherokee 4.0.
 

stilllearning wrote:
> On May 27, 11:20 am, Mike Romain <roma...@sympatico.ca> wrote:
>> Ok, I am on a fishing expedition for likely things to check.
>>
>> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
>> goes fine up to that point, then just bogs, no matter what gear it is
>> in. It has been neglected for 4 years as far as tuning goes due to me
>> not being up to it.
>>
>> I first changed out the 'very' dirty distributor cap and rotor which
>> made starting 'much' faster and smoother.
>>
>> I then changed the gas filter because it was once again rusted to the
>> rot point after about 8 years.
>>
>> Air filter is new.
>>
>> I cleaned the connections on the TPS and IAC and verified the TPS
>> doesn't have any 'dead' spots with my meter.
>>
>> I cleaned the CPS and coil connections also.
>>
>> No joy on any of that.
>>
>> I have been having some cold idle issues and have been thinking on
>> cleaning the IAC, but don't know if that will have a top end effect or not.
>>
>> I am also thinking on unplugging the EGR just to make sure it isn't
>> blown vacuum wise because it only bogs under throttle when things like
>> the EGR are active.
>>
>> Any other ideas?
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's
>> Canadian Off Road Trips Photos: Non members can still view!
>> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590
>> (More Off Road album links at bottom of the view page)
>
> What does exactly "then just bogs" mean? The Jeep does not go any
> faster, or it stalls and stops? What precise noises/knocks and
> symptoms, etc?

Stalls and stops and sputters until the gas pedal is let up on.

No backfires.

EGR now unplugged.


>
> On idle, what happens if you press accelerator until above half
> throttle? Is there a loss of power?

If I go fast on the pedal, there is a dead spot. No load and smooth
pedal seems to work.

>
> If the fuel pressure is low, the engine can run fine upto a point,
> until the demand for fuel exceeds the supply due to low pressure.
>

I knew there was a reason that filter was the second thing I went after.
;-) I don't have a pressure gauge other than a compression gauge though.

I also have verified the coil wire still has a connection with the ohm
meter. It is a bit higher per foot in resistance than the plug wires,
but only a bit, .7K vs .5K. Hmm the others I have around seem the same
too....

I made sure the main power had good connections also.

Mike

Re: Lost top end power in 88 Cherokee 4.0.
 

stilllearning wrote:
> On May 27, 11:20 am, Mike Romain <roma...@sympatico.ca> wrote:
>> Ok, I am on a fishing expedition for likely things to check.
>>
>> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
>> goes fine up to that point, then just bogs, no matter what gear it is
>> in. It has been neglected for 4 years as far as tuning goes due to me
>> not being up to it.
>>
>> I first changed out the 'very' dirty distributor cap and rotor which
>> made starting 'much' faster and smoother.
>>
>> I then changed the gas filter because it was once again rusted to the
>> rot point after about 8 years.
>>
>> Air filter is new.
>>
>> I cleaned the connections on the TPS and IAC and verified the TPS
>> doesn't have any 'dead' spots with my meter.
>>
>> I cleaned the CPS and coil connections also.
>>
>> No joy on any of that.
>>
>> I have been having some cold idle issues and have been thinking on
>> cleaning the IAC, but don't know if that will have a top end effect or not.
>>
>> I am also thinking on unplugging the EGR just to make sure it isn't
>> blown vacuum wise because it only bogs under throttle when things like
>> the EGR are active.
>>
>> Any other ideas?
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's
>> Canadian Off Road Trips Photos: Non members can still view!
>> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590
>> (More Off Road album links at bottom of the view page)
>
> What does exactly "then just bogs" mean? The Jeep does not go any
> faster, or it stalls and stops? What precise noises/knocks and
> symptoms, etc?

Stalls and stops and sputters until the gas pedal is let up on.

No backfires.

EGR now unplugged.


>
> On idle, what happens if you press accelerator until above half
> throttle? Is there a loss of power?

If I go fast on the pedal, there is a dead spot. No load and smooth
pedal seems to work.

>
> If the fuel pressure is low, the engine can run fine upto a point,
> until the demand for fuel exceeds the supply due to low pressure.
>

I knew there was a reason that filter was the second thing I went after.
;-) I don't have a pressure gauge other than a compression gauge though.

I also have verified the coil wire still has a connection with the ohm
meter. It is a bit higher per foot in resistance than the plug wires,
but only a bit, .7K vs .5K. Hmm the others I have around seem the same
too....

I made sure the main power had good connections also.

Mike

Re: Lost top end power in 88 Cherokee 4.0.
 

stilllearning wrote:
> On May 27, 11:20 am, Mike Romain <roma...@sympatico.ca> wrote:
>> Ok, I am on a fishing expedition for likely things to check.
>>
>> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
>> goes fine up to that point, then just bogs, no matter what gear it is
>> in. It has been neglected for 4 years as far as tuning goes due to me
>> not being up to it.
>>
>> I first changed out the 'very' dirty distributor cap and rotor which
>> made starting 'much' faster and smoother.
>>
>> I then changed the gas filter because it was once again rusted to the
>> rot point after about 8 years.
>>
>> Air filter is new.
>>
>> I cleaned the connections on the TPS and IAC and verified the TPS
>> doesn't have any 'dead' spots with my meter.
>>
>> I cleaned the CPS and coil connections also.
>>
>> No joy on any of that.
>>
>> I have been having some cold idle issues and have been thinking on
>> cleaning the IAC, but don't know if that will have a top end effect or not.
>>
>> I am also thinking on unplugging the EGR just to make sure it isn't
>> blown vacuum wise because it only bogs under throttle when things like
>> the EGR are active.
>>
>> Any other ideas?
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's
>> Canadian Off Road Trips Photos: Non members can still view!
>> Jan/06http://www.imagestation.com/album/pictures.html?id=2115147590
>> (More Off Road album links at bottom of the view page)
>
> What does exactly "then just bogs" mean? The Jeep does not go any
> faster, or it stalls and stops? What precise noises/knocks and
> symptoms, etc?

Stalls and stops and sputters until the gas pedal is let up on.

No backfires.

EGR now unplugged.


>
> On idle, what happens if you press accelerator until above half
> throttle? Is there a loss of power?

If I go fast on the pedal, there is a dead spot. No load and smooth
pedal seems to work.

>
> If the fuel pressure is low, the engine can run fine upto a point,
> until the demand for fuel exceeds the supply due to low pressure.
>

I knew there was a reason that filter was the second thing I went after.
;-) I don't have a pressure gauge other than a compression gauge though.

I also have verified the coil wire still has a connection with the ohm
meter. It is a bit higher per foot in resistance than the plug wires,
but only a bit, .7K vs .5K. Hmm the others I have around seem the same
too....

I made sure the main power had good connections also.

Mike

Re: Lost top end power in 88 Cherokee 4.0.
 

> I have no real way to check for fuel pressure I don't think unless one
> of my old compression testers could be converted??
>
> The miss is pretty consistent.
>

I would use a guage capable of 100PSI, but your local parts store may rent
them.
A "miss" and "bogging down" are two different things. If it is a miss, I
would change plug wires just to eliminate that possibility, then if not
effective, follow the fuel pressure.

Re: Lost top end power in 88 Cherokee 4.0.
 

> I have no real way to check for fuel pressure I don't think unless one
> of my old compression testers could be converted??
>
> The miss is pretty consistent.
>

I would use a guage capable of 100PSI, but your local parts store may rent
them.
A "miss" and "bogging down" are two different things. If it is a miss, I
would change plug wires just to eliminate that possibility, then if not
effective, follow the fuel pressure.

Re: Lost top end power in 88 Cherokee 4.0.
 

> I have no real way to check for fuel pressure I don't think unless one
> of my old compression testers could be converted??
>
> The miss is pretty consistent.
>

I would use a guage capable of 100PSI, but your local parts store may rent
them.
A "miss" and "bogging down" are two different things. If it is a miss, I
would change plug wires just to eliminate that possibility, then if not
effective, follow the fuel pressure.

Re: Lost top end power in 88 Cherokee 4.0.
 

> I have no real way to check for fuel pressure I don't think unless one
> of my old compression testers could be converted??
>
> The miss is pretty consistent.
>

I would use a guage capable of 100PSI, but your local parts store may rent
them.
A "miss" and "bogging down" are two different things. If it is a miss, I
would change plug wires just to eliminate that possibility, then if not
effective, follow the fuel pressure.

Re: Re: Lost top end power in 88 Cherokee 4.0.
 

On Sun, 27 May 2007 15:23:32 -0400, Mike Romain <romainm@sympatico.ca>
wrote:

>Stalls and stops and sputters until the gas pedal is let up on.
>
>No backfires.
>
>EGR now unplugged.


Run it hard and make it bog and them pull over and remove a plug and
see if it is white or sooty. I tend to think you are getting a fuel
starvation here that surfaces at higher power settings. Hard to be
sure without feeling it but the plugs would confirm a lean out. Might
start by changing fuel filter like someone else suggested and maybe a
fuel pressure check too.
-----------------
TheSnoMan.com

Re: Re: Lost top end power in 88 Cherokee 4.0.
 

On Sun, 27 May 2007 15:23:32 -0400, Mike Romain <romainm@sympatico.ca>
wrote:

>Stalls and stops and sputters until the gas pedal is let up on.
>
>No backfires.
>
>EGR now unplugged.


Run it hard and make it bog and them pull over and remove a plug and
see if it is white or sooty. I tend to think you are getting a fuel
starvation here that surfaces at higher power settings. Hard to be
sure without feeling it but the plugs would confirm a lean out. Might
start by changing fuel filter like someone else suggested and maybe a
fuel pressure check too.
-----------------
TheSnoMan.com

Re: Re: Lost top end power in 88 Cherokee 4.0.
 

On Sun, 27 May 2007 15:23:32 -0400, Mike Romain <romainm@sympatico.ca>
wrote:

>Stalls and stops and sputters until the gas pedal is let up on.
>
>No backfires.
>
>EGR now unplugged.


Run it hard and make it bog and them pull over and remove a plug and
see if it is white or sooty. I tend to think you are getting a fuel
starvation here that surfaces at higher power settings. Hard to be
sure without feeling it but the plugs would confirm a lean out. Might
start by changing fuel filter like someone else suggested and maybe a
fuel pressure check too.
-----------------
TheSnoMan.com

Re: Re: Lost top end power in 88 Cherokee 4.0.
 

On Sun, 27 May 2007 15:23:32 -0400, Mike Romain <romainm@sympatico.ca>
wrote:

>Stalls and stops and sputters until the gas pedal is let up on.
>
>No backfires.
>
>EGR now unplugged.


Run it hard and make it bog and them pull over and remove a plug and
see if it is white or sooty. I tend to think you are getting a fuel
starvation here that surfaces at higher power settings. Hard to be
sure without feeling it but the plugs would confirm a lean out. Might
start by changing fuel filter like someone else suggested and maybe a
fuel pressure check too.
-----------------
TheSnoMan.com

Re: Re: Lost top end power in 88 Cherokee 4.0.
 

SnoMan <admin@snoman.com> wrote:

> Run it hard and make it bog and them pull over and remove a plug
> and see if it is white or sooty. I tend to think you are getting a
> fuel starvation here that surfaces at higher power settings. Hard
> to be sure without feeling it but the plugs would confirm a lean
> out. Might start by changing fuel filter like someone else
> suggested and maybe a fuel pressure check too.

Don't disagree with you at all but the OP says he already replaced the
fuel filter, my question: Is there another filter somewhere?

I had a Cherokee years back but I no longer have the service manuals so
I don't know if there is another filter.

What about the fuel vent? That's easy to check by driving with the gas
cap removed.

--
XS11E, Killing all posts from Google Groups
The Usenet Improvement Project: http://blinkynet.net/comp/uip5.html

Re: Re: Lost top end power in 88 Cherokee 4.0.
 

SnoMan <admin@snoman.com> wrote:

> Run it hard and make it bog and them pull over and remove a plug
> and see if it is white or sooty. I tend to think you are getting a
> fuel starvation here that surfaces at higher power settings. Hard
> to be sure without feeling it but the plugs would confirm a lean
> out. Might start by changing fuel filter like someone else
> suggested and maybe a fuel pressure check too.

Don't disagree with you at all but the OP says he already replaced the
fuel filter, my question: Is there another filter somewhere?

I had a Cherokee years back but I no longer have the service manuals so
I don't know if there is another filter.

What about the fuel vent? That's easy to check by driving with the gas
cap removed.

--
XS11E, Killing all posts from Google Groups
The Usenet Improvement Project: http://blinkynet.net/comp/uip5.html

Re: Re: Lost top end power in 88 Cherokee 4.0.
 

SnoMan <admin@snoman.com> wrote:

> Run it hard and make it bog and them pull over and remove a plug
> and see if it is white or sooty. I tend to think you are getting a
> fuel starvation here that surfaces at higher power settings. Hard
> to be sure without feeling it but the plugs would confirm a lean
> out. Might start by changing fuel filter like someone else
> suggested and maybe a fuel pressure check too.

Don't disagree with you at all but the OP says he already replaced the
fuel filter, my question: Is there another filter somewhere?

I had a Cherokee years back but I no longer have the service manuals so
I don't know if there is another filter.

What about the fuel vent? That's easy to check by driving with the gas
cap removed.

--
XS11E, Killing all posts from Google Groups
The Usenet Improvement Project: http://blinkynet.net/comp/uip5.html

Re: Re: Lost top end power in 88 Cherokee 4.0.
 

SnoMan <admin@snoman.com> wrote:

> Run it hard and make it bog and them pull over and remove a plug
> and see if it is white or sooty. I tend to think you are getting a
> fuel starvation here that surfaces at higher power settings. Hard
> to be sure without feeling it but the plugs would confirm a lean
> out. Might start by changing fuel filter like someone else
> suggested and maybe a fuel pressure check too.

Don't disagree with you at all but the OP says he already replaced the
fuel filter, my question: Is there another filter somewhere?

I had a Cherokee years back but I no longer have the service manuals so
I don't know if there is another filter.

What about the fuel vent? That's easy to check by driving with the gas
cap removed.

--
XS11E, Killing all posts from Google Groups
The Usenet Improvement Project: http://blinkynet.net/comp/uip5.html

Re: Lost top end power in 88 Cherokee 4.0.
 

Mike Romain wrote:

> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
> goes fine up to that point, then just bogs, no matter what gear it is
> in. It has been neglected for 4 years as far as tuning goes due to me
> not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor which
> made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to the
> rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end effect or
> not.
>
> I am also thinking on unplugging the EGR just to make sure it isn't
> blown vacuum wise because it only bogs under throttle when things like
> the EGR are active.
>
> Any other ideas?

I've had this situation twice. First time was a dying fuel pump - and it
progressed to dead pretty quickly. Second was a shorted cable to the CPS.
Didn't tie it back properly and the exhaust got it. Same symptoms, except
my max RPM was 1000-1200 RPM, period. Crept home at idle <g>.
--
Will Honea

Re: Lost top end power in 88 Cherokee 4.0.
 

Mike Romain wrote:

> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
> goes fine up to that point, then just bogs, no matter what gear it is
> in. It has been neglected for 4 years as far as tuning goes due to me
> not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor which
> made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to the
> rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end effect or
> not.
>
> I am also thinking on unplugging the EGR just to make sure it isn't
> blown vacuum wise because it only bogs under throttle when things like
> the EGR are active.
>
> Any other ideas?

I've had this situation twice. First time was a dying fuel pump - and it
progressed to dead pretty quickly. Second was a shorted cable to the CPS.
Didn't tie it back properly and the exhaust got it. Same symptoms, except
my max RPM was 1000-1200 RPM, period. Crept home at idle <g>.
--
Will Honea

Re: Lost top end power in 88 Cherokee 4.0.
 

Mike Romain wrote:

> Ok, I am on a fishing expedition for likely things to check.
>
> Our 88 Cherokee with the 4.0 has lost power above half throttle. It
> goes fine up to that point, then just bogs, no matter what gear it is
> in. It has been neglected for 4 years as far as tuning goes due to me
> not being up to it.
>
> I first changed out the 'very' dirty distributor cap and rotor which
> made starting 'much' faster and smoother.
>
> I then changed the gas filter because it was once again rusted to the
> rot point after about 8 years.
>
> Air filter is new.
>
> I cleaned the connections on the TPS and IAC and verified the TPS
> doesn't have any 'dead' spots with my meter.
>
> I cleaned the CPS and coil connections also.
>
> No joy on any of that.
>
> I have been having some cold idle issues and have been thinking on
> cleaning the IAC, but don't know if that will have a top end effect or
> not.
>
> I am also thinking on unplugging the EGR just to make sure it isn't
> blown vacuum wise because it only bogs under throttle when things like
> the EGR are active.
>
> Any other ideas?

I've had this situation twice. First time was a dying fuel pump - and it
progressed to dead pretty quickly. Second was a shorted cable to the CPS.
Didn't tie it back properly and the exhaust got it. Same symptoms, except
my max RPM was 1000-1200 RPM, period. Crept home at idle <g>.
--
Will Honea