1992 Isuzu Rodeo Question High Idle

Tiny
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  • 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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Monday, April 19th, 2010 AT 3:44 PM

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Tiny
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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)

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Tuesday, April 20th, 2010 AT 3:38 AM
Tiny
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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.

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Wednesday, April 21st, 2010 AT 2:48 PM
Tiny
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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)

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Wednesday, April 21st, 2010 AT 5:15 PM
Tiny
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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

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Wednesday, April 21st, 2010 AT 6:17 PM
Tiny
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I would replace the ICM.

Mark

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Wednesday, April 21st, 2010 AT 7:27 PM
Tiny
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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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Monday, April 26th, 2010 AT 1:57 PM
Tiny
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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.

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Monday, April 26th, 2010 AT 2:16 PM
Tiny
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No I dont have cruise control.

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

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Monday, April 26th, 2010 AT 4:11 PM
Tiny
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It doesn't make a difference about checking the throttle cable for binding.

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Wednesday, April 28th, 2010 AT 12:51 PM
Tiny
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So I should remove the cable at both ends and completely remove it?

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Wednesday, April 28th, 2010 AT 1:51 PM
Tiny
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Not yet! Remove at the throttle body, and if the idle drops to normal, operate it by hand and rev it then let it go, if it returns to a normal idle, replace the cable. See if the throttle plate closes fully.

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Wednesday, April 28th, 2010 AT 1:59 PM
Tiny
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Throttle cable checked out find and throttle plate closes fully. Still doing the same thing. Where should we go from here.

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Tuesday, May 4th, 2010 AT 1:32 PM
Tiny
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Has the timing been checked/set to 10 BTDC at below 1000 RPM? There is a tech bulletin on this...
Reference Number(s): SB93-02-002
Related Ref Number(s): SB93-02-002
ARTICLE BEGINNING
RODEO (UC) AND PICKUP (TF) 3.1L V6 IDLE SPEED/IGNITION
TIMING SPECIFICATIONS (WORKSHOP MANUAL CORRECTION)
Model(s): 1991-92 Isuzu Rodeo, 1991-92 Isuzu Pickup
Group: Fuel
Bulletin No.: SB93-02-002
Date: December, 1993
AFFECTED VEHICLES
1991-92 Rodeo (UC) and Pickup (TF) models equipped with 3.1L V6 engine.
SERVICE INFORMATION
Idle speed and ignition timing specifications for affected vehicles are incorrectly described in the
following Workshop Manuals:
This Service Bulletin contains the correct idle speed & ignition timing specifications for the
referenced workshop Manual pages as well as revised Vehicle Emission Control Information label
illustration.
The correct vehicle specifications for the 3.1L V-6 engine are:
No adjustment to " idle speed is required.
" Ignition timing is 10 BTDC under 1000 rpm.
IDLE SPEED/TIMING - WORKSHOP MANUAL CORRECTION -1992 Isuzu Rodeo S Page 1 of 2
http://www.


http://www.2carpros.com/forum/automotive_pictures/62217_set_timing_1.jpg



http://www.2carpros.com/forum/automotive_pictures/62217_vac_diag_1.jpg


Checked for vacuum leaks? You may have a vacuum leak, get a can of spray Throttle body cleaner, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! Keep spray off the exhaust manifolds and pipes! Fire hazard!

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Tuesday, May 4th, 2010 AT 1:48 PM

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