Another Low Idle Cherokee
04-17-2017, 03:56 PM
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Another Low Idle Cherokee
Ive got a 1996 Jeep Cherokee (4.0 I6) with about 185,000 on it. Last tune up was about 6,000 miles ago. New plugs, wires, rotor, cap, air filter, etc. About a month ago my idle just dropped to about 200 rpms. It's not rough or trying to stall out, but its obviously very low and Im worried.
So far i've tested the fuel pressure at the schrader valve. 49 psi at idle. Tested the MAP sensor. Voltage input is 5V. Numbers were spot on doing vacuum test. Ground is fine. Then I tested the TPS which ended up being bad as it had a dead spot when opening the throttle steadily. So I replaced the TPS. Replaced the IAC as well since cleaning it didnt help anything. I also pulled the entire throttle body off and deep cleaned it and seafoamed the engine. Still, nothing has solved it. When i crank it up my idle sits at 600 rpms for a few seconds then steadily decreases to 200 where it stays. Also, at random, my jeep will hesitate while driving. Never stalled completely though.
The only issue I know I have yet to be resolved is a rattling catalytic converter. My jeep smogged just fine last month but the mech told me I should replace it. Could the cat be my low idle issue and/or hesitation problem?
Any other suggestions so I could rule anything else out?
thx
So far i've tested the fuel pressure at the schrader valve. 49 psi at idle. Tested the MAP sensor. Voltage input is 5V. Numbers were spot on doing vacuum test. Ground is fine. Then I tested the TPS which ended up being bad as it had a dead spot when opening the throttle steadily. So I replaced the TPS. Replaced the IAC as well since cleaning it didnt help anything. I also pulled the entire throttle body off and deep cleaned it and seafoamed the engine. Still, nothing has solved it. When i crank it up my idle sits at 600 rpms for a few seconds then steadily decreases to 200 where it stays. Also, at random, my jeep will hesitate while driving. Never stalled completely though.
The only issue I know I have yet to be resolved is a rattling catalytic converter. My jeep smogged just fine last month but the mech told me I should replace it. Could the cat be my low idle issue and/or hesitation problem?
Any other suggestions so I could rule anything else out?
thx
04-17-2017, 04:19 PM
#2
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Year: 1997
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Engine: 4.0L
Could be the convertor. Even a partially clogged convertor can affect the idle. The exhaust cant pass as easily so the engine starts choking on its own fumes. This can show up at idle and everyday driving. Should it clog completely, the engine might not even start. Or it will start, but stall soon after. If it rattles, check the heat shield first. The tack welds can break loose and rattle. Mine did that.
As for the TPS, what brand did you replace it with? Mopar is best. Same goes for the IAC.
As for the TPS, what brand did you replace it with? Mopar is best. Same goes for the IAC.
04-17-2017, 08:54 PM
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Could be the convertor. Even a partially clogged convertor can affect the idle. The exhaust cant pass as easily so the engine starts choking on its own fumes. This can show up at idle and everyday driving. Should it clog completely, the engine might not even start. Or it will start, but stall soon after. If it rattles, check the heat shield first. The tack welds can break loose and rattle. Mine did that.
As for the TPS, what brand did you replace it with? Mopar is best. Same goes for the IAC.
As for the TPS, what brand did you replace it with? Mopar is best. Same goes for the IAC.
