'89 4.0L VERY high idle problem
 

I have recently acquired an 89 Jeep Cherokee with an inline 6 cyl which is
fuel injected. It quite suddenly developed a dangerous problem with the
idle speed. At idle it sits at anywhere between 2300 to 3300 rpm so you
almost have to have 2 feet on the brakes at a stop sign. When I pull the
vacuum hose off the map sensor it drops down to about 1100 with some white
smoke out the tailpipe. I pulled the tps out to see if it was maybe stuck
but it seemed okay and moved freely. I am not sure where to go from here
to fix this thing. Anyone else with a similar problem?

Re: '89 4.0L VERY high idle problem
 

Disconnecting your Manifold Absolute Pressure sensor tells me the
problem is there or in the way your computer is interpreting that
information. Sounds like the most common idle step motor problem is
working properly. Might find a way to diagnose it via:
http://www.----------.com/temp/89JeepFI.pdf I once gave up, and just
closed off the step motor with a beer can, and used the throttle stop
screw.
God Bless America, Bill O|||||||O
mailto:--------------------

scmadhatter wrote:
>
> I have recently acquired an 89 Jeep Cherokee with an inline 6 cyl which is
> fuel injected. It quite suddenly developed a dangerous problem with the
> idle speed. At idle it sits at anywhere between 2300 to 3300 rpm so you
> almost have to have 2 feet on the brakes at a stop sign. When I pull the
> vacuum hose off the map sensor it drops down to about 1100 with some white
> smoke out the tailpipe. I pulled the tps out to see if it was maybe stuck
> but it seemed okay and moved freely. I am not sure where to go from here
> to fix this thing. Anyone else with a similar problem?

Re: '89 4.0L VERY high idle problem
 

Disconnecting your Manifold Absolute Pressure sensor tells me the
problem is there or in the way your computer is interpreting that
information. Sounds like the most common idle step motor problem is
working properly. Might find a way to diagnose it via:
http://www.----------.com/temp/89JeepFI.pdf I once gave up, and just
closed off the step motor with a beer can, and used the throttle stop
screw.
God Bless America, Bill O|||||||O
mailto:--------------------

scmadhatter wrote:
>
> I have recently acquired an 89 Jeep Cherokee with an inline 6 cyl which is
> fuel injected. It quite suddenly developed a dangerous problem with the
> idle speed. At idle it sits at anywhere between 2300 to 3300 rpm so you
> almost have to have 2 feet on the brakes at a stop sign. When I pull the
> vacuum hose off the map sensor it drops down to about 1100 with some white
> smoke out the tailpipe. I pulled the tps out to see if it was maybe stuck
> but it seemed okay and moved freely. I am not sure where to go from here
> to fix this thing. Anyone else with a similar problem?

Re: '89 4.0L VERY high idle problem
 

Disconnecting your Manifold Absolute Pressure sensor tells me the
problem is there or in the way your computer is interpreting that
information. Sounds like the most common idle step motor problem is
working properly. Might find a way to diagnose it via:
http://www.----------.com/temp/89JeepFI.pdf I once gave up, and just
closed off the step motor with a beer can, and used the throttle stop
screw.
God Bless America, Bill O|||||||O
mailto:--------------------

scmadhatter wrote:
>
> I have recently acquired an 89 Jeep Cherokee with an inline 6 cyl which is
> fuel injected. It quite suddenly developed a dangerous problem with the
> idle speed. At idle it sits at anywhere between 2300 to 3300 rpm so you
> almost have to have 2 feet on the brakes at a stop sign. When I pull the
> vacuum hose off the map sensor it drops down to about 1100 with some white
> smoke out the tailpipe. I pulled the tps out to see if it was maybe stuck
> but it seemed okay and moved freely. I am not sure where to go from here
> to fix this thing. Anyone else with a similar problem?

Re: '89 4.0L VERY high idle problem
 

(sigh) Is there anything that beer can't do?

>I once gave up, and just closed off the step motor with a beer can, and used the throttle stop screw.

Re: '89 4.0L VERY high idle problem
 

(sigh) Is there anything that beer can't do?

>I once gave up, and just closed off the step motor with a beer can, and used the throttle stop screw.

Re: '89 4.0L VERY high idle problem
 

(sigh) Is there anything that beer can't do?

>I once gave up, and just closed off the step motor with a beer can, and used the throttle stop screw.

Re: '89 4.0L VERY high idle problem
 

On Fri, 14 Oct 2005 21:00:15 UTC "scmadhatter" <scmattern@cox.net>
wrote:

> I have recently acquired an 89 Jeep Cherokee with an inline 6 cyl which is
> fuel injected. It quite suddenly developed a dangerous problem with the
> idle speed. At idle it sits at anywhere between 2300 to 3300 rpm so you
> almost have to have 2 feet on the brakes at a stop sign. When I pull the
> vacuum hose off the map sensor it drops down to about 1100 with some white
> smoke out the tailpipe. I pulled the tps out to see if it was maybe stuck
> but it seemed okay and moved freely. I am not sure where to go from here
> to fix this thing. Anyone else with a similar problem?

First off. pul the connector on the tps with contact cleaner (or WD40
in a pinch). after you plug it back in, take a volt meter and check
the voltages. I can't remember which pins are which, but with the key
on (don't start it) probe the plug from the wire side. One pin should
read 5 volts, one about .9 volts, the third zero - that's ground.
probe the one that reads about .9 (or somewhere between about .5 and
4.9 some-odd) as you move the throttle cable - it should vary smoothly
with no breaks. If you can't find a pin that does vary from just
under 1 volt to something close to 5 volts, you have a shot tps. If
the tps checks out then what you describe could well be the MAP
sensor. Probe it the same way, but you really need a vacuum pump
(hand style) or good lungs to see if the reading changes as pressure
changes. AIR, the MAP sensor is relatively cheap - $20 range.

The dirty TPS connector is a common problem on the old Renix systems.

--
Will Honea

Re: '89 4.0L VERY high idle problem
 

On Fri, 14 Oct 2005 21:00:15 UTC "scmadhatter" <scmattern@cox.net>
wrote:

> I have recently acquired an 89 Jeep Cherokee with an inline 6 cyl which is
> fuel injected. It quite suddenly developed a dangerous problem with the
> idle speed. At idle it sits at anywhere between 2300 to 3300 rpm so you
> almost have to have 2 feet on the brakes at a stop sign. When I pull the
> vacuum hose off the map sensor it drops down to about 1100 with some white
> smoke out the tailpipe. I pulled the tps out to see if it was maybe stuck
> but it seemed okay and moved freely. I am not sure where to go from here
> to fix this thing. Anyone else with a similar problem?

First off. pul the connector on the tps with contact cleaner (or WD40
in a pinch). after you plug it back in, take a volt meter and check
the voltages. I can't remember which pins are which, but with the key
on (don't start it) probe the plug from the wire side. One pin should
read 5 volts, one about .9 volts, the third zero - that's ground.
probe the one that reads about .9 (or somewhere between about .5 and
4.9 some-odd) as you move the throttle cable - it should vary smoothly
with no breaks. If you can't find a pin that does vary from just
under 1 volt to something close to 5 volts, you have a shot tps. If
the tps checks out then what you describe could well be the MAP
sensor. Probe it the same way, but you really need a vacuum pump
(hand style) or good lungs to see if the reading changes as pressure
changes. AIR, the MAP sensor is relatively cheap - $20 range.

The dirty TPS connector is a common problem on the old Renix systems.

--
Will Honea

Re: '89 4.0L VERY high idle problem
 

On Fri, 14 Oct 2005 21:00:15 UTC "scmadhatter" <scmattern@cox.net>
wrote:

> I have recently acquired an 89 Jeep Cherokee with an inline 6 cyl which is
> fuel injected. It quite suddenly developed a dangerous problem with the
> idle speed. At idle it sits at anywhere between 2300 to 3300 rpm so you
> almost have to have 2 feet on the brakes at a stop sign. When I pull the
> vacuum hose off the map sensor it drops down to about 1100 with some white
> smoke out the tailpipe. I pulled the tps out to see if it was maybe stuck
> but it seemed okay and moved freely. I am not sure where to go from here
> to fix this thing. Anyone else with a similar problem?

First off. pul the connector on the tps with contact cleaner (or WD40
in a pinch). after you plug it back in, take a volt meter and check
the voltages. I can't remember which pins are which, but with the key
on (don't start it) probe the plug from the wire side. One pin should
read 5 volts, one about .9 volts, the third zero - that's ground.
probe the one that reads about .9 (or somewhere between about .5 and
4.9 some-odd) as you move the throttle cable - it should vary smoothly
with no breaks. If you can't find a pin that does vary from just
under 1 volt to something close to 5 volts, you have a shot tps. If
the tps checks out then what you describe could well be the MAP
sensor. Probe it the same way, but you really need a vacuum pump
(hand style) or good lungs to see if the reading changes as pressure
changes. AIR, the MAP sensor is relatively cheap - $20 range.

The dirty TPS connector is a common problem on the old Renix systems.

--
Will Honea