1991 cherokee won't idle

[redneckXJ]

For about a week my cherokee has been running a little funny, it started out just idling low when I was in 4low and came to a stop. That was the only time it would do it. Then it progressed into stalling every once in a while when coming to a stop in 4low. This is within just a few days. Then I fire it up to go to work one morning about a day later and it runs really rough, like it has a misfire. So I replaced the plugs and wires, now about a week later it will not idle at all, if I let off the throttle it dies. I can stab it and haul ass no problem, runs great at high rpm. I checked to see if it would throw any codes and all it reads is a 12, 55. Wich is that the battery has been disconnected recently. I don't really know where to start on this thing an I was hoping to take it to ocotillo wells in a week and a half. Any input on where I should start would be much apriciated!

[nickyg]

Throttle position sensor? here's a write up on how to test it
http://www.jeepforum.com/forum/f11/how-test-tps-610386/

[4.3LXJ]

The place to start is cleaning the idle air controller. That won't cost you anything and fixes it 90% of the time

[redneckXJ]

Thanks guys for the quick responses! Once I get home from work I'll pull the idle air control valve and see if that helps. I'm thinkin it will at least help a little, the car has 235k on it and I'm sure hasn't had much more than a regular oil change all it's life.

[redneckXJ]

So, I cleaned my IAC and it didn't help, replaced the TPS, didn't help. Then the check engine light came on and it threw a 52. Wich I looked up and showed a bad o2 sensor. Replaced that. Still runs like crap at idle and nearly dies when I come to a stop. Where to go from here??

[4.3LXJ]

Just for giggles, disconnect the battery and reconnect. Let the computer learn all over again. Your idle air controller may not be working properly

[redneckXJ]

Tried the battery trick, still nothing. I also figured out if I hold it at say, 1500rpm in neutral or park and hold it there it will stay there for a second and then drop about 300-500rpm and run super rough. Then after a few seconds climb back up and run smooth for a few seconds and then drop and run rough.

[redneckXJ]

I also re looked up the code it threw and it is a rich air/fuel mixture. What would cause it to run rich. I forgot to add I am not running a cat, but it has been that way for months with no problems.

[4.3LXJ]

Does it act like it is not getting enough fuel? Might check your fuel pressure while it is running

[redneckXJ]

No not really, cause I can stomp on it and it runs great. It's only at idle and mostly when I'm coming to a stop.

[4.3LXJ]

Temp sensor working properly?

[redneckXJ]

As far as I know it does. The guage reads just under 210 all the time untill I'm off-road going slow and it will climb up, fan kicks on and it cools down.

[oderdene]

check vacuum lines and MAP, are connectors clean and contacting properly?

[redneckXJ]

Figured it out! I was checking out all my vacuum lines and the one that goes to the MAP sensor was cracked! Thank you guys for the help!

[2fastjeep]

I had a similar stalling problem mine would die after getting off the highway. Turnd out to be my fuel pump was failing. Might take a second look at your fuel systems.

Sent from my GS3 via tapatalk

[nickyg]

Glad you found it.