Hesitation & Stalling

[MUR]

Has anyone figured this out? I have a 98 Cherokee w/60,000 miles and when you start up and start driving it wants to die, it actually has died once.
Has New Tune Up
Changed IAT Sensor
Checked the TPS

What else would cause this?

[AlohaBra]

Crank Position Sensor (CPS).

[MUR]

Well it's not the crank position sensor and the timing was check,not that either. The computer is giving a faulty reading at the Intake Air Temperature Sensor, when unplugged it's not going to default @ -32 degrees so we were told the computer is more than likely bad.
Any thoughts???

[refrigerationdude]

Doubt its the computer...hope not at least. Try cleaning the throttle body and IAC w/ throttle body cleaner, its like $4 at an auto parts store. Mine had been doing this recently, sometimes hesitating badly and not starting up after sitting an hour or 2, like it'd try to start, fire weakly on a few cylinders and die, crank again it fired up fine and ran fine then. But it'd do just what yours is occasionally when started cold, act like it was missing and wanted to die then pick up and go. I was told by a friend to check the TB and IAC, and I did find a lot of carbon buildup in the TB. Cleaned it and it hasn't done that hesitation yet since, and it seems to run much smoother now too. Not sure if it'll still act up starting as it only does that once and awhile and seems to come and go, and its only when it sits like an hour - 2 hrs it does it, if its longer or shorter durations it starts fine on 1st try.

Hope its not the computer, if mine starts acting up again I don't wanna be lookin at the computer. Then again I thought there was a correlation between resetting it, by dropping a batt cable, it seemed it wouldnt do the starting thing for awhile after doing that, then it'd start acting up again. So who knows maybe it is electronically related.

Let us know what it is when you find it.

[AlohaBra]

Could be a bad battery shorting out in the cells.

[MUR]

The battery was actually the first thing I did, I forgot to mention that. I took it to the mechanic and he cleaned all the connectors to the computer, thinking it could be corrosion, and that worked for a couple of hours and it started hesitating again. We may be leaning towards trying a new computer

[baum430]

Originally Posted by MUR

The battery was actually the first thing I did, I forgot to mention that. I took it to the mechanic and he cleaned all the connectors to the computer, thinking it could be corrosion, and that worked for a couple of hours and it started hesitating again. We may be leaning towards trying a new computer

take off the vacuum line to the map sensor at the throttle body this line
will get clogged from normal use ,carbon buildup, clean entire TB and line
to map sensor. also change O2 sensor if it needs it ,O2 is good for
about 80,000 miles.

[MUR]

Please Help, this has been at our Mechanics for over a week and he cannot find what is wrong with the Jeep. He checked every sensor, all the wiring, all the vacuum lines, everything with the fuel, throttle body, some intake valve in the throttle body, reprogrammed the computer.
Now we have to start the Jeep let it run until it starts to act up, hesitate and trying to stall, press on the gas pedal until it straightens out and then you can drive it and it runs good. We have to do this each time we start it up
The check engine light did not come on for us but it did for the mechanic and all that said was the transmission wasn't talking to the computer, he straightened that out but we still have the problem.

[MUR]

I was wrong on the fuel system, nothing was checked.
I was looking at another website and it says the following:
POSSIBLE CAUSES:

Fused ignition switch output circuit
Fuel pump relay defective
Fuel pump relay control circuit for open
Fuel pump relay control circuit for short to ground
Fuel pump relay wiring harness observable defect
Fuel pump relay wiring harness intermittent defect
PCM defective

What do you think!

[AlohaBra]

AT 60K...if it has the original battery....replace it.
Did anyone do voltage drop tests on the ground cable?
Do voltage drop test on positive cable while you are at it.
Anything else should bring up a check engine light.
Still say...replace crank position sensor...known..big trouble.

[MUR]

The check engine light finally came on, the shop said it was the 02 sensor and needed the fuel injection cleaned so we had this done and the check engine went off, well after letting it sit for awhile they took it for a test drive and it still was hesitating and wanting to stall. The check engine light came on again and finally replaced the Idle Air Control Motor and now so far so good. While they were at it we went ahead and had them change the spark plugs because the Jeep had been running rough for a long time (doesn't hurt)

Hope this helps!

[AlohaBra]

Reelly...is this a Jeep dealer???

The crank position sensor needs to replaced anyway, because it always fails, because of its routing over the top of the transmission.

I thought you did your own work instead of letting shops "guess" at your problem.

[I have owned three XJs (Cherokees)] Aloha...

[MUR]

This is a Jeep dealer, I was tired of replacing parts and not fixing the problem so I took it to the dealer to get it fixed.