I have a 1994 Jeep Cherokee 4.0l.

its starts fine but when i put it in drive is wants to stall unless i give it gas, because when im driving it runs good but once i idle at a stop light it stalls. one of the vac lines that conects from airbox to the valve cover was unpluged so i reconected it and it runs a little better but still stalls anyone know anything else i can check to see what the problem is. anything would help.. thanks

 

1. A common cause of stalling is a marginal battery. And yes, you can have a battery strong enough to start the engine, but marginal enough to create stalling. I answer about three threads a week at least on this.

2. Check to see if there are any stored codes. Here is how.

http://www.go.jeep-xj.info/HowtoECUcodes.htm

3. Tuneup hardware fresh? Plugs, wires, distributor cap, rotor, fuel filter

4. Get a fuel pressure gauge and install it on the schrader valve on the fuel rail. Compare your readings to factory spec. and then WATCH that gauge to see if you are losing fuel pressure as the engine fails

5. Still problematic after performing 1-4? Test your throttle position sensor.

 

Could be a bad idle air control motor. I know some will say to clean it, but just replace it and save the headache of removing it twice.

 

I had this exact same problem. I cleaned my IAC, cleaned the throttle body, didn't help to much. Tested my battery and alternator, and the battery was bad. It was holding enough charge to start it, and the alternator was going great, just the battery didn't hold much charge after the start.

If you 2 petal it, you can get where ever you need to go. If you have a good working battery somewhere else, swap it out and see how it runs. I bought a new one and it runs perfect ever since. I noticed the shorter the trips I made, the harder the start and lower rpms it started at.

 

Where is the IAC located?? And now its only really doing it when it warms up.

 

It is attached with two screws to your throttle body, with a wire going into it. Very easy to get off, even easier to get off if you remove the whole throttle body.

 

I took it off and it was all gunked up... i cleaned it the best i could it didnt make any differance.. just got new spark plugs and wires, i spent the money and got the good stuff.. im going to get a battery tomorrow..

 

When you go to get the new battery, might as well ask them to test the old one before you invest in a new one. Most well known auto parts stores will do it free, would suck to buy a new battery and not have it solve your problem. Also, when you cleaned the IAC, make sure to get inside where it attaches as well. May not solve your problem, but when it is fixed, you should notice a smoother idle either way.

 

If none of the above suggestions fix your problem, this almost sounds like what would happen if the torque converter was stuck in the locked position.

 

see what confuses me is when i took it up to get tested they said the battery and alternator where good, but there is no way to test the batt to see if its marginal??

 

The only accurate way to test a battery is a LOAD TEST. It is a specialized test that any parts store can do, but it is the only accurate way of testing a battery. If that parts store that did the testing didn't specifically run a LOAD TEST, then your battery has not been properly tested.

 

i just said screw it and replaced the battery with a new one.. still does it, im going to check all of the vac lines and im going to clean the throttle body tomorrow morning when its light.. hopefully i can figure this out.. thanks for all the help.

 

There is a chance it could be the tps or cps, but you would have other symptoms if those were going bad. If all else fails, might try at least testing those to see if they are the problem.

 

unplug your iac and take it off, now plug the connector back in and notice where the pintle is,probably sticking out far, then go turn your ignition key on (not running) and see if the pintle moves inward. if it doesnt, its bad. new one costs around 60 bucks. see if the hole it goes into is full crap too and clean that out with throttle cleaner.

 

Above is good advice. The idle air control is still in play. Cleaning CAN, but does not always restore full function if there is a mechanical problem.

And definitely clean that throttle body. Use throttle body cleaner, not carb cleaner as TB cleaner is safe for the coating that is on your throttle body.