Mechanics

QUESTION HIGH IDLE

1992 Isuzu Rodeo

Engine Performance problem
1992 Isuzu Rodeo Question 6 cyl Four Wheel Drive Manual 144, 00 miles

okay, so I have a 1992 isuzu rodeo v-6 4wd with around 144,000 miles on it. When I first crank my car in the morning its goes up to around 1800 rpms. After about 5 minutes it will drop to around 1200 rpms and that is as far down as it will go. I can then drive around and after about 5 minutes rpms will drop to normal.
I can then park car and go shopping and when I crank up. Rpms will go to around 1500, then a couple of seconds later drop back to normal. It has been doing this for around 4 months now. Any help will be greatly appreciated. Thank you
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Swtpea76
April 19, 2010.




Hi there,

Thank you for the donation,

The idle speed is controlled by the ECU and a idle control motor, I would start with cleaning the idle motor ports and checking for vacuum leaks as this will also hold a high idle speed, start here.

Mark (mhpautos)

Mhpautos
Apr 20, 2010.
So I tried that and still does the same thing. I crank the car and rpms still go up to around 2000 and after about 5 minutes they drop to maybe 1200. Also when I turn the steering wheel hard left or right the rpms go down a bit.

Tiny
Swtpea76
Apr 21, 2010.
I would be thinking that the idle control motor is faulty, did you do the scan and check for any unresolved fault codes?

Mark (mhpautos)

Mhpautos
Apr 21, 2010.
Service engine light is not on and I did not get any fault codes.I did get a code for faulty coolant temp sensor a few months back, but I replaced that and code went away

Tiny
Swtpea76
Apr 21, 2010.
I would replace the ICM.

Mark

Mhpautos
Apr 21, 2010.
Someone suggested I replace the Idle Air Control Valve. So I did that and nothing changed, still does the same thing. Is that the same thing as the ICM.
Where should I go from here.
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Tiny
Swtpea76
Apr 26, 2010.
Does it have cruise control? If yes remove the cable for cruise control at the throttle, if that works OK, if not remove throttle cable, one of them may be holding the throttle open a bit.

Merlin2021
Apr 26, 2010.
No I dont have cruise control.

My car is 1992 Isuzu Rodeo 3.1 V-6 TBI Manual tranny if that makes any difference

Tiny
Swtpea76
Apr 26, 2010.
It doesn't make a difference about checking the throttle cable for binding.

Merlin2021
Apr 28, 2010.
So I should remove the cable at both ends and completely remove it?

Tiny
Swtpea76
Apr 28, 2010.

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