High Idle: TPS or IAC?
05-31-2013 | 04:25 PM
#31
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Ok, I adjusted the TPS and now the idle tops out at 1100rpm, but stayed under 1000 for the most part on my trip through town. I might get a vacuum line kit from the dealership this summer to at least get those freshened up.
DFlinstone, it does not really follow your pattern, but the idle smooths out a bit then drops 100-200rpm and lopes a few times then returns to normal. The whole cycle is about 25 seconds, but at no time does it sound like the engine is about to stall out. I heard it stumble once, but that's it.
But more recently, the whole jeep has been vibrating at an idle like the rotating assembly is out of balance, but it doesn't knock any more or less than it did before. Actually, when I got back from grocery shopping I couldn't hear the rod knock that it developed this winter. Is this a sign of a bad motor mount?
DFlinstone, it does not really follow your pattern, but the idle smooths out a bit then drops 100-200rpm and lopes a few times then returns to normal. The whole cycle is about 25 seconds, but at no time does it sound like the engine is about to stall out. I heard it stumble once, but that's it.
But more recently, the whole jeep has been vibrating at an idle like the rotating assembly is out of balance, but it doesn't knock any more or less than it did before. Actually, when I got back from grocery shopping I couldn't hear the rod knock that it developed this winter. Is this a sign of a bad motor mount?
Throttle body and IAC cleaned? Intake manifold bolts tight? Sprayed with throttle body cleaner all over the intake to check for vacuum leaks? Hose from TB to MAP is perfect?
05-31-2013 | 06:29 PM
#32
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Joined: Nov 2011
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From: Northern MN
Year: 1990
Model: Cherokee (XJ)
Engine: Renix 4.0
I just went out and sprayed around and found no leaks, so mission accomplished there, but now the throttle has an intermittent stumble when I accelerate. It stalled out when I was turning around in a really rough parking lot. But it also did it on a flat road, and I hit some speed bumps to see if it would stumble again but it was fine. Once the engine cools I'm gonna pull the spark plugs and look at them. What else should I check? Fuel pressure?
05-31-2013 | 06:52 PM
#33
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From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
It seems, than when a renix, (titania), 02 sensor is dead the idle will fluctuate every 20-30 seconds. Also running rich will make it sluggish to come up to temp. Millage will suck as well of course. First checking it's ground and heater power makes sense. A new one won't work any better if you don't have that. The link right on top here has info on the 02 sensor. > https://www.cherokeeforum.com/f2/ren...ce-rms-133153/
05-31-2013 | 06:57 PM
#34
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Joined: Aug 2011
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
I just went out and sprayed around and found no leaks, so mission accomplished there, but now the throttle has an intermittent stumble when I accelerate. It stalled out when I was turning around in a really rough parking lot. But it also did it on a flat road, and I hit some speed bumps to see if it would stumble again but it was fine. Once the engine cools I'm gonna pull the spark plugs and look at them. What else should I check? Fuel pressure?
05-31-2013 | 07:01 PM
#35
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Joined: Nov 2011
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From: Northern MN
Year: 1990
Model: Cherokee (XJ)
Engine: Renix 4.0
Originally Posted by cruiser54
I had a bad ground wire between the fuel pump and th flange on the fuel pump/gauge module causing issues kinda like yours. Here's a pic of the wire:
05-31-2013 | 07:28 PM
#40
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Joined: Aug 2011
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From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
at 16 I had the license and the wheels. My 'friends" seemed to have plenty of gas....
Without actually having done it....I can siphon some from my 90 if I park it right. Then with the nose up, the pump port will be higher. I wonder if a guy with a jack and stands could make that work....
Without actually having done it....I can siphon some from my 90 if I park it right. Then with the nose up, the pump port will be higher. I wonder if a guy with a jack and stands could make that work....
06-02-2013 | 05:08 PM
#41
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Joined: Nov 2011
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From: Northern MN
Year: 1990
Model: Cherokee (XJ)
Engine: Renix 4.0
Ok, so I opened up the tank today and made sure the ground was securely connected, it was. So I went for a little drive and it spit and sputtered even worse! Then it died and wouldn't start again. So under the hood I went. For what ever reason I grabbed the ignition coil wire, it was loose so I clamped it on there with my multitool. Then I noticed the loose grounding battery terminal... It was all mangled so I put my extra terminal end on and tightened it down. The engine fired right up, and drove out of the lot just fine. Then I hit a bump and it all came back. I'm so confused on this one.
06-02-2013 | 05:31 PM
#42
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Joined: Nov 2011
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From: Northern MN
Year: 1990
Model: Cherokee (XJ)
Engine: Renix 4.0
I searched and found this, it's exactly the same problem! I don't understand how it could be the TPS though 
http://mikestrawbridge.com/blog/2012...okee-stumbles/
http://mikestrawbridge.com/blog/2012...okee-stumbles/
06-05-2013 | 06:26 PM
#43
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Joined: Nov 2011
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From: Northern MN
Year: 1990
Model: Cherokee (XJ)
Engine: Renix 4.0
Ok, so I followed that guy's post about his TPS. I exchanged my new TPS for another, installed and adjusted it, same issue. It's not even every bump it cuts out on, and it will do it idling. Could a bad connection with the O2 sensor cause this? I have a pacesetter and spliced in some longer leads and maybe they are now loose? Could the knock sensor do this too? I'm so fried out on this.