1992 Isuzu Rodeo Question High Idle

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)

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.

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)

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

I would replace the ICM.

Mark

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.

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.

no i dont have cruise control.

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

It doesn't make a difference about checking the throttle cable for binding...

so i should remove the cable at both ends and completely remove it?

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.

Throttle cable checked out find and throttle plate closes fully. Still doing the same thing. Where should we go from here.

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.

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!