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So it idles fine sometimes and not others? It'* important so we don't waste time. If it idles right at all then we can eliminate certain things like a vacuum leak.
It did idle correctly sometimes before I did all the work to it. Since then it has idled at 1500-2000. I replaced the IAC with no change.
Also, it'* extremely hard to start when cold. It'* been that way since I bought it. Unfortunately I had to meet the guy somewhere when I first looked at it, so it was already warmed up. I guess he forgot to tell me about it being hard to start...
It did idle correctly sometimes before I did all the work to it. Since then it has idled at 1500-2000. I replaced the IAC with no change.
It used to id;e OK and now after doing the gaskets it'* always high? If so, You have a vacuum leak or the intake gasket was not in the correct placement.
What is engine load doing at idle?
It used to id;e OK and now after doing the gaskets it'* always high? If so, You have a vacuum leak or the intake gasket was not in the correct placement.
What is engine load doing at idle?
I don't remember seeing that on my scanner. I'll check again. While I had it running I sprayed carb cleaner all around the uim gasket but found nothing. I also blew smoke in the the big vacuum line from the brake booster to the nipple on the back side of the plenum. I did catch a tiny bit of smoke coming out from somewhere around that nipple and the injector closest to it.
Did you spray around that area and no idle change? The load is calculated by a few inputs. Load is what the PCM uses to calculate fuel delivery.
The PCM looks at Throttle Position (TPS), RPM and airflow (MAF).
I'll see if I can get the numbers you should see.
I'd like to see what these values are now on your tool.
Yes, no idle change. I haven't been able to get it started since I saw the little bit of smoke coming out. I wanted to try again with the carb cleaner now that I have a better idea of where the leak may be. I may go ahead and pull the plenum off and reseat/re-torque everything too. I thought a vacuum leak would cause the motor to die. It could cause the high idle too?
Yep, the extra air can allow that if it'* not too much. It'* like having the throttle open a little more but not measuring that air. When this is happening, it will naturally run lean, but will adjust mixture to compensate.
I bought a 96 Park Avenue base for my son to drive when he turns 16 in a few months. 150000 miles, clean car, pretty much everything works except the fuel door popper.
It needed upper and lower intake gaskets and valve cover gaskets, really hard to start when cold and would randomly idle at 1500 to 2000 rpm.
I started it up after I replaced all the gaskets and still have the high idle. I replaced the IAC motor. I tried to test the plug for TPS but the only thing I know for sure is it'* got the 5v reference signal, I can't tell if the ground is good and I can't test the voltage as the throttle is moved because I don't have any pins to back probe with. I have a cheap Bluetooth scanner/code reader and I might be able to test the TPS with that. I cleaned the MAF while I had the throttle body off, which I also cleaned up. I also repaired a vacuum leak while I was putting the top of the motor back together. No other vacuum leaks that I can find.
No leaks from the valve covers or plenum, she just won't idle right. It won't take much for this car to be good to go if I can get the idle fixed. Thanks for reading all this! Any ideas?
GM issued a TSB to replace the TPS in older cars if they had almost any symptoms of issues, i would go ahead and replace with OEM and make sure to install it properly (there is a wrong way to do it)
And the IAC has a reset procedure
Can you post your VIN, I will check to see if GM had any PCM updates to correct for a hunting idle
none of these would fix your issue, but are you able to find your calibration with a scan tool? Because its worth flashing the PCM with an update if you dont have the chuggle update (chuggle is a sensation felt at TCC lockup at 30-50mph)
02-17-2024, 11:12 AM
