Hello all,

My Monty would idle pretty smooth at about 750 but every once in awhile it would drop down to about 200-250 and the back up to 750ish. I thought I would clean the ISC motor and throttle body. I disconnected the battery then I removed the motor and wiped it clean with a shop rag (It really wasn't very dirty) I then cleaned the throttle body(what I could reach) by spraying TB cleaner on a rag and wiping out the body(It wasn't too bas either but looking through into the plenum-NOW THATS NASTY -cant reach that though) I also reamed out and cleaned the breather hose that goes from the valve cover to the large air intake hose attached to the throttle body(It was nearly gooed shut)Anyway--I put it all back together, connected the battery and started the truck. The idle immediately surged to about 2000 rpm I waited for the computer to 'relearn itself' waiting for the idle to stabilize(about 10 min.) It never went below 900. Took it for a drive and when I returned, sitting in my garge idling-the idle surged up to 1500-2000 and back to 900. It did this about 10-15 times until I shut it off. Drove about 60 miles to the in-laws. During the trip, idle would fluctuate between 950-and 750. Got to the in-laws and the surging started again in the driveway. Shut off the motor. <img src="/forums/images/graemlins/confused.gif" alt="" /> Drove home. Hasn't done the surging crap again but it steadies at 950-1000 and occasionaly drops to 750. Noticed in the Chilton it says to 'listen for the motor' with the key on without the engine running to verify its operation. Did this last night and hear nothing nor do I feel it vibrating at all when I place my hand on it. I am in your hands 'Master Forumsmen '

-Aaron

P.S. I pulled the codes and #14 TPS sensor comes up. Not sure how much effect this has on idle....

95 SR 3.5 V6 DOHC

Sounds like idle control motor. Disconnect connector. Check resistance at motor side of connector. You should have the following or the motor is defective.
Between green wire with red stripe and green wire with black stripe--------28-33 ohms @ 70 degrees F
Between gray wire with black stripe and green wire with blue stripe--------28-33 ohms @ 70 degrees F
If this checks ok, check your TPS for sticking or high voltage at idle.

Idle Control Motor tested fine -all coils measured 29-30 ohms. Harness measured 12.5V. Still not idling smooth. It's not the ISC. Guess cleaning gunk out of TB isn't such a good idea after all. This car is beginning to make me <img src="/forums/images/graemlins/barf.gif" alt="" />

-Aaron

95 Montero SR 3.5L V6 DOHC

I have an IAC tester that I use to test the PCM output to the motor. It has a pair of two color LEDS that flash rapidly to indicate proper operation of the PCM. They are ~$20 at most auto parts stores.

After determining the PCM is putting out the right signals, I take the IAC out of the TB, plug it back into the harness and hold it with one finger over the pintle and my thumb on the opposite end. Then I have a buddy turn on the ignition and back off again. You'll know i fit works. You may have to screw the pintle back into the motor if it pops out while testing, but this always meant to me that it was time for a new one. You're already headed toward replacing that sucker anyway so what do you have to lose?

Clay