Low idle in park, rough idle in gear, stalls at stops

Tiny
WRDELLINGER
  • MEMBER
  • 1995 JEEP GRAND CHEROKEE
  • 4.0L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 260,000 MILES
This car is very old. As old as me actually, but I'm doing my best to fix it up myself. The problem started with stalling at stops. Now I can put it in gear and it trembles before I even move. Idle never goes higher than 600 and dips as low as 200! I've cleaned the entire throttle and IACV but no luck.
Tuesday, January 27th, 2015 AT 9:46 PM

3 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 34,086 POSTS
Old! What do you mean "old"? My daily driver is a rusty trusty '88 Grand Caravan!

If the battery was recently disconnected or run dead the Engine Computer lost its memory and has to relearn "minimum throttle" before it will know when it must be in control of idle speed. The engine will be hard to start unless you hold the gas pedal down 1/4". It also might not give you the normal "idle flare-up" to 1500 rpm when you start the engine, and the engine will want to stall when coming to a stop. To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the brake or gas pedals.
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Tuesday, January 27th, 2015 AT 10:18 PM
Tiny
WRDELLINGER
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  • 1 POST
I guess I was mostly describing the level of upkeep. There are several problems beyond this but running properly is my priority of course. Anyhow, I really appreciate the advice but the idle is so poor I can't get this thing on the highway. The last time I put it in reverse, it stalled when I stopped to change gears.
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Wednesday, January 28th, 2015 AT 9:55 PM
Tiny
CARADIODOC
  • MECHANIC
  • 34,086 POSTS
If it's stalling due to a misfire, you have to address that first. Beyond that, when minimum throttle hasn't been relearned, you'll likely have to drive with two feet and keep one on the accelerator all the time.
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Thursday, January 29th, 2015 AT 8:17 AM

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