Still having high idle problem on 88 Jeep Comanche (4.0l)

I've got some contact cleaner, as well as some WD40. I'll maybe give that a whirl.

As far as suppliers goes, that's the kind of price I was hoping/expecting. But apparently up here in Canada, they make them things out of gold. On the plus side, if I find an old Jeep, I'm pretty sure I can haul that piece off in about 2 minutes! :) I'm getting very intimate with my throttle area...

Cl>

Reply to
Clint
Loading thread data ...

If you have a multimeter, here are the pinouts for the TPS.

With the key in run and the engine and AC off, you put the meter into the back side of the plug and take a voltage reading. With the throttle at rest, the volts should be 200 MV. At wide open, the volts should be

4.8V max. They should smoothly increase as the throttle opens.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail > I've got some contact cleaner, as well as some WD40. I'll maybe give > that a whirl.
Reply to
Mike Romain

To go off on a (yet another) small tangent, is there a way to test the IAS to make sure it's working correctly?

BTW, I took off the TPS, and tested the resistance as it rotated through it's range. But without having a known good one, all I can say is that it does go through a range of resistances smoothly.

I also learned something today, and I'm going to post it in the interest of assisting others. Otherwise I'd just hide my red face behind the computer screen. When putting the TPS on, the default position seemed to have the lever arm on the wrong side of the throttle body arm. This would cause the TPS to be rendered pretty much useless, as far as I can see, as it won't move with the throttle body lever. Whoops. So just watch that if you need to replace/adjust that.

Clint

Reply to
Clint

Does your meter not have a volt setting?

Mike

Cl> To go off on a (yet another) small tangent, is there a way to test the

Reply to
Mike Romain

I measured before, and was getting < .5V. But whether it was exactly .2V or not, my meter didn't give me confidence enough to say yeah or nay.

Clint

Reply to
Clint

There is a special tool my book calls an 'exerciser' to test the idle stepper. The book sort of implies a high moves the pintle out and a low in, but it doesn't say for sure.

It, the ISS has a moving part that can stand to be cleaned.

Mike

Cl> I measured before, and was getting < .5V. But whether it was exactly

Reply to
Mike Romain

Be careful. Never start the engine with the IAS motor removed or the little pintle will shoot across the garage and the unit is toast.

With the ignition on, motor not running.

back-probe the connector and find the ground and +5v (should be the outside two wires) If there isn't 5v there then you might have a break in the harness or just not a good contact with the wire. Now measure the center wire against the ground.

Throttle butterfly Voltage CLOSED >200 mV OPEN

Reply to
DougW

So I went out to a local wrecker, and they had about 6 Cherokee's, all of about the right vintage. 3 of them still had their IAC's, but all of them were automatic's, so I couldn't yank the TPS's. Kind of disappointed by the lack of selection on those.

Anyway, the "new" IAC only cost $2 (the entire throttle body with add-ons was only $20), but it had exactly the same effect as the old one. *sigh* So I'm still looking for a TPS to plug in there.

Anyone know if the automatic tranny version of the sensor has any hope of working? Or would I just be asking for even more pain?

Clint

Reply to
Clint

Now I am more thinking you are missing something... CCV unplugged or one of the lines to the air filter box. There is one way down low in the front by the rad that controls the heat pipe for the air filter.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail > So I went out to a local wrecker, and they had about 6 Cherokee's, all
Reply to
Mike Romain

Left or right side? Can you give me more specific directions on what I'm looking for (besides a dangling hose)? Should I be looking up from underneath?

All these problems (idling) seemed to start when I replaced the rad and water pump, so this very well could be the culprit.

Clint

Reply to
Clint

I will look tomorrow on mine for sure, but I think it is at the bottom front side of the air filter box. There should be an outlet there for a heat pipe that runs to the exhaust to suck hot air when the engine is cold. These heat pipe hoses usually rot away but there is a vacuum motor down there to turn it on. It would be a small vacuum line on a nipple. My Haynes implies there could be a vacuum line on the fender side of this motor.

Mike

Cl> Left or right side? Can you give me more specific directions on what

Reply to
Mike Romain

Well, I've definately got a rotted away hose, so I'm assuming that's the heat pipe hose. I'll go take a look. That rotted hose is right where the radiator hoses attached, so if there was any vacuum hoses around there, they'd be at risk of getting bumpted in the setup of the new rad. The FSM doesn't show anything funky in the vacuum diagram in that area, however. But I'd sure be happy to be proven wrong!

Thanks again.

Clint

Reply to
Clint

Never mind. I checked it out. There is a square box on the front of the air filter box that the rotted hose goes into. On the fender side, there is an airhose that runs into a nipple on the top of the square box. All that is still connected.

Nice when the FSM vacuum diagram so closely matches reality. Or am I expecting too much? The funky toilet float in the bumper isn't shown either, and I've checked both those hoses as well.

Clint

Reply to
Clint

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.