Rough IDLE '93 Jeep Gr Chero Laredo

flykr2s · #1 02-17-2006, 01:53 PM

1993 Jeep Grand Cherokee Laredo 4.0L with 234,000 miles.
I have a rough idle that I can not get rid of and I NEED HELP PLEASE.
I have installed all of the following new components: plugs, dist cap, rotor, MAP sensor, TPS sensor, Crank Sensor, O2 Sensor, fuel pump, fuel filter, fuel regulator, air filter, PCV, and I have removed and cleaned the throttle body. The Jeep will idle rough at stops like it wants to die but never does. I also am having difficulty starting it when the temps are really cold out like below freezing. The only things that I have not done that I can think of are replacing the coil and plug wires and the camshaft position sensor. I am losing my mind trying to figure this out...HELP PLEASE

txstateMarcus · #2 02-17-2006, 08:09 PM

Bro, that is exactly what is going on with mine. I have also replaced everything you have except the crank position sensor. Here is one more interesting characteristic...When I change out the plugs, it will start and run fine until it gets up to operating temp. and then idles rough below 1100 rpm. above 1100 rpm it runs fine. Im about to give up and drop it off at the dealership. If I come back w/good news i will definitely let you know.
-Marcus

GregA · #3 02-18-2006, 02:08 AM

Quote:

Originally Posted by flykr2s

I have installed all of the following new components: ...

I didn't see the Idle Air Control (IAC) Valve on the list. Of course you would have to check all the wires & connections to it too. Here is some more information.

Jeep 4.0L IAC Valve

Take Care,

flykr2s · #4 02-20-2006, 08:35 AM

Solved!!!! Possibly. Previously, I had removed the throttle body and cleaned it real good including the IAC and pintle seat area. I also checked the electrical to the IAC but found no problems there so I re-installed the complete assembly and still had the problem. Well, Friday on the way home from work I decided to stop and buy a new IAC since I figured what's another $40 at this point. I think that has solved my problem. So far, three days later, she is running perfect with no idle problems. Heck, with all the new components I have added to this engine, I should get another 233,000 out of it. If the problem returns, I will let you all know. Thanks for all the help.

flykr2s · #5 02-22-2006, 08:22 AM

NOT SOLVED as I had previously posted saying it was solved. I installed a new IAC and the Jeep ran great for three days with absolutely no rough idle....well IT IS BACK !!!! I am about ready to drive this piece of crap into Lake Michigan and watch it sink. Don't get me wrong, I love the Jeep but I an so frustrated that I just do not know what to do any longer. Now I have another issue....last night I filled the tank and now the fuel gauge works intermittantly and keeps going from full to empty and back. This also causes the low fuel light to come on and go off plus the DTE on the info console is now screwed up. I just installed a new fuel pump and strainer two weeks ago and this is the first time I had a fuel gauge problem.

Anybody else going wacko with continous problems?

flykr2s · #6 02-23-2006, 10:52 AM

Well, the rough idle continues. Last night, I checked the resistance of the coil with an ohm meter and found it to be in tolerance. I then checked the resistance on the plug wires and found two to be low around 3K while the rest were up about 7k. I also checked the plugs which only have 15K miles on them and they looked great. So, I replaced the plug wires with new ones and the ROUGH IDLE STILL IS THERE. Somebody, please HELP ME before I lose my mind over this. Thanks

legalfee · #7 02-23-2006, 11:08 AM

My gut feeling is the IAC is still the problem. The one you installed worked for a while (3 days). Something caused it to go bad or it went bad after 3 days. You could try an OEM part (Chrysler Mopar). I think there's a way to test it. SJ

RLR25 · #8 02-23-2006, 09:51 PM

I just bought the same kind of jeep just a few days ago for fishing/hunting is has 187,000 miles on it everything seems to work perfect except it has a rough idle also!!! Drives fine and smooth when rpms are over 1000. Is there any advice on what to fix or clean first?

teemsta · #9 02-24-2006, 11:17 PM

my 94 jgcl 5.2 has the exact problem also... rough idle under 1000 rpm then runs perfect over that. I was playing around with the engine the other day and took out the pcv valve and just shook it around. went to the store later and jeep rans like new for a while. I am going to change it tommorrow t see if that is no good. if you pull the hose from it, it changes the engine idle so hopefully i have a bad pcv and a new one will cure it. will post on my results soon.

dksob81 · #10 02-25-2006, 07:36 AM

Yes a clogged PCV Valve would cause a rough idle.

FLYKR2S
What are your RPM's at when idling, is it below 500? Did you disconnect the battery before replacing the IAC Valve?
It is a must to disconnect the battery on Jeeps before replacing any elextrical component.

flykr2s · #11 03-06-2006, 10:41 AM

PROBLEM SOLVED: Finally.....I replaced the coil and now the car runs like a brand new one. Maby I can get another 235K miles out of it. Thanks for all the help guys.

PaulaTaylor01 · #12 03-10-2006, 11:14 AM

Mine is doing the same thing! Rough idle, replaced everything (95 GCLaredo), taken it to certified repair places, seems to help temp. but then starts the rough idle again. I think this needs to be a recall issue. There seems to be too many people having the same problem. If you know how to start a recall, please let me know at [email protected]. I have read in Consumer Reports that older models had an issue with a "Defective air control motor". I thought this thing had an air control value, not a motor. Anybody know? Help! I have thrown away hundreds of dollars in this thing and still not got it fixed. Email me if you have the solution.

dksob81 · #13 03-11-2006, 07:42 AM

Quote:

Originally Posted by PaulaTaylor01

Mine is doing the same thing! Rough idle, replaced everything (95 GCLaredo), taken it to certified repair places, seems to help temp. but then starts the rough idle again. I think this needs to be a recall issue. There seems to be too many people having the same problem. If you know how to start a recall, please let me know at [email protected]. I have read in Consumer Reports that older models had an issue with a "Defective air control motor". I thought this thing had an air control value, not a motor. Anybody know? Help! I have thrown away hundreds of dollars in this thing and still not got it fixed. Email me if you have the solution.

The Air Control Motor and Air Control Valve (IDLE AIR CONTROL VALVE, to be precise) are one in the same. Some people just call it different things.

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