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I just recently posted about idle problem on my ’02 Montana. Now, I just read there is a re-learn process when you replace the IAC and TPS, which I have replaced both and the high idle problem continues to drive me nuts. Anyone tell me how to do a re-learn on a ’02 Montana? I have found SO many different sites on the web and they all say to do it different. ANY help would be so much appreciated. :unsure:
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the Montana has a 3400 SFI engine, the the IAC and Throttle position sensor i believe doesn’t require re learned in this vehicle since it doesn’t have electronic throttle control! in fact i had a car with its smaller syster engine the 3100 SFI and did a throttle body swap putting a 3400 throttle body on that engine, and after some idling the IAC adjusted itself and the TPS did as well it was totally bolt on plug in and play.
Hello, I’m pretty familiar with this engine. I don’t know that a relearn procedure would be necessary. The PCM should revert to the pre programmed settings for the IAC and TPS and adjust accordingly. I could be wrong here.
Here is an idea or two, followed by a question.
First, you may have a simple vacuum leak. This can cause high idle. Check your vacuum line from the pcv valve line where it mounts into the top of the front valve cover. Then check it where it routes to the purge solenoid (just behind throttle body and in front of EGR valve). Also, check the vacuum line at the fuel pressure regulator and where it routes to the MAP sensor at the back middle of the plenum. Don’t overlook the big main vacuum line coming into the plenum from the brake booster. Eric has some helpful videos about how to check for vacuum leaks.
A second suggestion would be to purchase a simple vacuum gauge (if you don’t already have one) and see what the reading indicates. There is a vacuum test port at the right front of the plenum near the fuel pressure regulator.
Did the high idle originally start out of the blue, or had you done any other work to the vehicle lately? Did either the IAC or TPS throw a diagnostic trouble code?
Best of luck. Keep us posted. tomatofarmer1
i believe you have posted on here before hensley1378 concerning your idle being very high at points?
Out of the GM training manual:
BASE IDLE RELEARN
The ECM/PCM will reset the idle air control valve whenever the ignition switch is turned to the “On” position, then to the “Off” position. However, before you return the car to the customer, it is best to bring the engine up to operating temperature in Park with the air conditioning off. Then, turn the air conditioning on. Next, turn the air conditioning off. Next, place the transmission selector in drive. Finally, with the car in Drive, turn the air conditioning on.
Thanks for your time, tomatofarmer. Yes, it started right after I replaced the egr valve. It run like a new one for a couplr of days and then it started out the blue. Soooo…I started throwing parts at it (bad idea) TPS, IAC, New plugs, wires, coil pak,but none made any difference. When it does run of idle, it runs great, but randomly it will run up on the idle and stay there until I shut the engine off and it alwyas starts right back up and then the idle is fine at650 rpms until next time. Thanks in advance for any help.
I haven’t changed my IAC on the 94 3.9L v6 yet but I have the new part (Standard brand) and in the box instructions say I should measure how far the pintle on the one I am removing sticks out from mating surface to the tip. There is a procedure if the new one sticks out more to shorten it. It says there could be damage to the inside of the TB if you insert it without doing this.
The relearn process is essentially driving at 40MPH at normal running temp for a bit to cause the pintle to fully extend and mate with the inner surface thus giving the PCM a set point to work form.I’m thinking the procedure would be very similar and yours should have had instructions with it.
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