engine idle slowly climbs to 1500 rpm
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Joined: Jan 2010
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From: Lyons, Oregon
Year: 1991
Model: Cherokee
Engine: 4.0 HO
I installed the IAC, haven't driven it much yet. I did check the CPS, it's all over the place, from .3 to .7. Will this affect it while it's running? I don't have a no start issue.
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Joined: Aug 2011
Posts: 10,489
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From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Zit a 91? there might be a way to check that CPS, but it takes a high end meter. Maybe I missed something. It's easy on the two wire, pre 91. Much different for the three wire.
My CPS functioned till about .3. Ran much better with the new..I had gotten use to slow starts and less than smooth running. With the new I saw what I was missing. Pete is the man, of course, but if you see 3.5 + AC volts on that two wire, you might be OK there.
Change a CPS. A jack-stand under the left frame might be in your way. BACKING onto ramps is an option. Sometimes when I lift a vehicle, I see if I can push it off it's “lift” before I go underneath. You lay on your back with your feet out under the passenger side. With your LEFT hand you can reach up past the front drive-line to hold the CPS. (if your forearm is smaller than a quart mason jar)(if not maybe pull the drive-line). It's 7/16-or 11mm bolts on the older Jeeps. You want 11mm. or 7/16 socket,> 3 inch extension,> swivel,> then 18 to 24 inches of extension to your RIGHT hand , down on the ratchet by the tranny cross member. If there is a plastic deal there, can it. DON'T drop a bolt in there! (just don't!!!). When you are starting out, if you tie a long string, 5ive feet, to the old plug, you can then use that to haul the new one back up.
If your wires go through a metal band secured by an engine to bell housing bolt, cut them. To finish, zip tie, or make darn sure the wires won't rub/chafe or burn on anything. The second one is a relative piece if cake! (½ hr job!)
My CPS functioned till about .3. Ran much better with the new..I had gotten use to slow starts and less than smooth running. With the new I saw what I was missing. Pete is the man, of course, but if you see 3.5 + AC volts on that two wire, you might be OK there.

Change a CPS. A jack-stand under the left frame might be in your way. BACKING onto ramps is an option. Sometimes when I lift a vehicle, I see if I can push it off it's “lift” before I go underneath. You lay on your back with your feet out under the passenger side. With your LEFT hand you can reach up past the front drive-line to hold the CPS. (if your forearm is smaller than a quart mason jar)(if not maybe pull the drive-line). It's 7/16-or 11mm bolts on the older Jeeps. You want 11mm. or 7/16 socket,> 3 inch extension,> swivel,> then 18 to 24 inches of extension to your RIGHT hand , down on the ratchet by the tranny cross member. If there is a plastic deal there, can it. DON'T drop a bolt in there! (just don't!!!). When you are starting out, if you tie a long string, 5ive feet, to the old plug, you can then use that to haul the new one back up.
If your wires go through a metal band secured by an engine to bell housing bolt, cut them. To finish, zip tie, or make darn sure the wires won't rub/chafe or burn on anything. The second one is a relative piece if cake! (½ hr job!)
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From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Thread Starter
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Joined: Jan 2010
Posts: 536
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From: Lyons, Oregon
Year: 1991
Model: Cherokee
Engine: 4.0 HO
DF, it's an auto. I'm probably going to let it go for now, no probs starting, it just stalls every now and then in drive when you touch the accelerator pedal to get going. Hasn't done it since I put in the IAC but I haven't driven it but a couple miles so far.
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