HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

98 zj, 6 cyl. Runs rough after starting, when engine warm runs smooth.
No check engine light. Have done maintenance in following order
1. New plugs, new wires,new rotor,new cap
1a. Took off fuel rail; full of crap, install fuel rail and do injection
flush.
Worked great for about 3 weeks symptoms reappear.
2. Drop fuel tank have steam cleaned, replace intank fuel pump, do a
injection flush from fuel tank forward.
Now have about $1200 invested in repairs and symptoms are still there.

Have hooked up the dealer pilot computer to record conditions when symptoms
occur with nil negative pick ups
Dealer has done there chemical carbon cleaning of intake valves, twice
dealer baroscopic the valves and there is no carbon on valves

Have replaced the following with no positive results;
Crankshaft Position sensor
O2 sensors
Engine Coolant Sensor
The Main Computer

No check engine light and runs rough when cold when first accelerating as
the accelerator is push vehicle will smooth out and
accelerate, like its missing on some cylinders.
Does not latch any code.

Matt
0|||||||0
Tact is the ability to describe others as they see themselves

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

1a. Took off fuel rail; full of crap, install fuel rail and do
injection
flush.
Worked great for about 3 weeks symptoms reappear.

Sounds like you still have an injector problem. Try hooking up a noid
light to each one while the engine is cold. If that passes muster,
they may all have to be pulled for further testing and cleaning.

What sort of 'crap' are we talking about here? Corrosion maybe? What
type/brand of fuel were you running? Ethanol content?

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

1a. Took off fuel rail; full of crap, install fuel rail and do
injection
flush.
Worked great for about 3 weeks symptoms reappear.

Sounds like you still have an injector problem. Try hooking up a noid
light to each one while the engine is cold. If that passes muster,
they may all have to be pulled for further testing and cleaning.

What sort of 'crap' are we talking about here? Corrosion maybe? What
type/brand of fuel were you running? Ethanol content?

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

1a. Took off fuel rail; full of crap, install fuel rail and do
injection
flush.
Worked great for about 3 weeks symptoms reappear.

Sounds like you still have an injector problem. Try hooking up a noid
light to each one while the engine is cold. If that passes muster,
they may all have to be pulled for further testing and cleaning.

What sort of 'crap' are we talking about here? Corrosion maybe? What
type/brand of fuel were you running? Ethanol content?

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

Just reg gas from Canadian Tire no ethenol., but they have been flushed
twice,
what is a noid light and what is the test procedure
Thanks for the reply JD.


Matt
0|||||||0
Tact is the ability to describe others as they see themselves
"JD Adams" <JDAdams@Softcom.Net> wrote in message
news:1143245234.995431.15120@i40g2000cwc.googlegro ups.com...
> 1a. Took off fuel rail; full of crap, install fuel rail and do
> injection
> flush.
> Worked great for about 3 weeks symptoms reappear.
>
> Sounds like you still have an injector problem. Try hooking up a noid
> light to each one while the engine is cold. If that passes muster,
> they may all have to be pulled for further testing and cleaning.
>
> What sort of 'crap' are we talking about here? Corrosion maybe? What
> type/brand of fuel were you running? Ethanol content?
>

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

Just reg gas from Canadian Tire no ethenol., but they have been flushed
twice,
what is a noid light and what is the test procedure
Thanks for the reply JD.


Matt
0|||||||0
Tact is the ability to describe others as they see themselves
"JD Adams" <JDAdams@Softcom.Net> wrote in message
news:1143245234.995431.15120@i40g2000cwc.googlegro ups.com...
> 1a. Took off fuel rail; full of crap, install fuel rail and do
> injection
> flush.
> Worked great for about 3 weeks symptoms reappear.
>
> Sounds like you still have an injector problem. Try hooking up a noid
> light to each one while the engine is cold. If that passes muster,
> they may all have to be pulled for further testing and cleaning.
>
> What sort of 'crap' are we talking about here? Corrosion maybe? What
> type/brand of fuel were you running? Ethanol content?
>

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

Just reg gas from Canadian Tire no ethenol., but they have been flushed
twice,
what is a noid light and what is the test procedure
Thanks for the reply JD.


Matt
0|||||||0
Tact is the ability to describe others as they see themselves
"JD Adams" <JDAdams@Softcom.Net> wrote in message
news:1143245234.995431.15120@i40g2000cwc.googlegro ups.com...
> 1a. Took off fuel rail; full of crap, install fuel rail and do
> injection
> flush.
> Worked great for about 3 weeks symptoms reappear.
>
> Sounds like you still have an injector problem. Try hooking up a noid
> light to each one while the engine is cold. If that passes muster,
> they may all have to be pulled for further testing and cleaning.
>
> What sort of 'crap' are we talking about here? Corrosion maybe? What
> type/brand of fuel were you running? Ethanol content?
>

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

Was the maintenance done because of the miss? If not how much was
before and after?

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)

jeepr wrote:
>
> 98 zj, 6 cyl. Runs rough after starting, when engine warm runs smooth.
> No check engine light. Have done maintenance in following order
> 1. New plugs, new wires,new rotor,new cap
> 1a. Took off fuel rail; full of crap, install fuel rail and do injection
> flush.
> Worked great for about 3 weeks symptoms reappear.
> 2. Drop fuel tank have steam cleaned, replace intank fuel pump, do a
> injection flush from fuel tank forward.
> Now have about $1200 invested in repairs and symptoms are still there.
>
> Have hooked up the dealer pilot computer to record conditions when symptoms
> occur with nil negative pick ups
> Dealer has done there chemical carbon cleaning of intake valves, twice
> dealer baroscopic the valves and there is no carbon on valves
>
> Have replaced the following with no positive results;
> Crankshaft Position sensor
> O2 sensors
> Engine Coolant Sensor
> The Main Computer
>
> No check engine light and runs rough when cold when first accelerating as
> the accelerator is push vehicle will smooth out and
> accelerate, like its missing on some cylinders.
> Does not latch any code.
>
> Matt
> 0|||||||0
> Tact is the ability to describe others as they see themselves

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

Was the maintenance done because of the miss? If not how much was
before and after?

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)

jeepr wrote:
>
> 98 zj, 6 cyl. Runs rough after starting, when engine warm runs smooth.
> No check engine light. Have done maintenance in following order
> 1. New plugs, new wires,new rotor,new cap
> 1a. Took off fuel rail; full of crap, install fuel rail and do injection
> flush.
> Worked great for about 3 weeks symptoms reappear.
> 2. Drop fuel tank have steam cleaned, replace intank fuel pump, do a
> injection flush from fuel tank forward.
> Now have about $1200 invested in repairs and symptoms are still there.
>
> Have hooked up the dealer pilot computer to record conditions when symptoms
> occur with nil negative pick ups
> Dealer has done there chemical carbon cleaning of intake valves, twice
> dealer baroscopic the valves and there is no carbon on valves
>
> Have replaced the following with no positive results;
> Crankshaft Position sensor
> O2 sensors
> Engine Coolant Sensor
> The Main Computer
>
> No check engine light and runs rough when cold when first accelerating as
> the accelerator is push vehicle will smooth out and
> accelerate, like its missing on some cylinders.
> Does not latch any code.
>
> Matt
> 0|||||||0
> Tact is the ability to describe others as they see themselves

Re: HELP 98 GRAND CHEROKEE ROUGH RUNNING
 

Was the maintenance done because of the miss? If not how much was
before and after?

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)

jeepr wrote:
>
> 98 zj, 6 cyl. Runs rough after starting, when engine warm runs smooth.
> No check engine light. Have done maintenance in following order
> 1. New plugs, new wires,new rotor,new cap
> 1a. Took off fuel rail; full of crap, install fuel rail and do injection
> flush.
> Worked great for about 3 weeks symptoms reappear.
> 2. Drop fuel tank have steam cleaned, replace intank fuel pump, do a
> injection flush from fuel tank forward.
> Now have about $1200 invested in repairs and symptoms are still there.
>
> Have hooked up the dealer pilot computer to record conditions when symptoms
> occur with nil negative pick ups
> Dealer has done there chemical carbon cleaning of intake valves, twice
> dealer baroscopic the valves and there is no carbon on valves
>
> Have replaced the following with no positive results;
> Crankshaft Position sensor
> O2 sensors
> Engine Coolant Sensor
> The Main Computer
>
> No check engine light and runs rough when cold when first accelerating as
> the accelerator is push vehicle will smooth out and
> accelerate, like its missing on some cylinders.
> Does not latch any code.
>
> Matt
> 0|||||||0
> Tact is the ability to describe others as they see themselves