1997 Cadillac Deville 126000 miles. The vehicle runs at a very high idle in all gears. 3000 rpm in Park, 4000 in Neutral, 1750-2250 in Drive and 1750 in Reverse. The car wants to roll through stop signs on its own and accelerates up to 50 with out using the gas pedal. When I drive it (which I don’t want to with this condition) I only use the brake to control my speed.
The previous owner said that replacing the IACV had fixed the issue, which is no longer the case. Unless those two screws need to be torqued.
It shifts really hard between P,N,R,D,3,2,1. While moving the vehicle please turn it off in gear and put into park after shut down.
I have:
Had the system checked for vacuum leaks (none were found).
Reset the ECU/PCM by disconnecting the battery.
Cleaned the throttle body and replaced the gaskets.
Replaced the Idle Air Control Valve.
Replaced the MAF and MAF air tube.
Replaced the PCV Valve.
My thoughts (I am by no means an expert).
Throttle cable adjustment?
Reset PCM.
PCM flash?
Random A/C refrigerant low light.
Throttle cable adjustment?
So this car has a cable that opens the throttle body? When the car is off, remove the air intake so you can see the throttle body, is it open?
At first I was thinking you may have an issue with an electronic throttle body or the sensor in the gas pedal that reads its position. Obviously if you cars throttle body is cable driven that couldnt be the case. Either way this sounds pretty dangerous. May want to hand it over to a good mechanic.
When I took the TB apart both times (once to clean and once to replace the thin gasket between the two metal portions of the TB) it was closed. I'm going to make an appointment with the dealership. I've done all I feel comfortable with at this point.
Check that the throttle cable is properly adjusted and not binding at the pedal and the mounting point on the TB. Check for proper connections and function of the IAC and correct or replace as necessary.
The IAC is brand new and placed correctly, I'm not sure if I need to torque it to have it work properly. The throttle cable at the TB mount does have a slight bend in it but it goes flush against the mount when I depress the throttle spring. I haven't checked the pedal side of things yet. The TB opens and shuts properly as well. So I'm going to ask the dealership to scope out the cable, double check for vacuum leaks and possibly reflash the PCM.
It’s really clean inside and out but it’s been to the shop a bunch. The dealership has fixed some electrical issues and it’s gotten a replacement PCM for a really high idle.
In an attempt to bring down the high idle on my own I cleaned the throttle body, replaced the gaskets/seals after cleaning, replaced the IAC valve, replaced the MAF and MAF tube between the air filter and throttle body and had it checked for vacuum leaks at my trusted local shop, they said no leaks were found.
I had a new PCM put in to get rid of the extremely high idle (4000 in park). The newer PCM helped but the car is still popping a P0507 code “IAC is running high DTC priority 2 out of 3” In park it’s still running high 1000-1200 RPM.
It has an oil leak and I’m wondering if one of the seals that is cracked or warped is allowing air into the engine and helping to cause the high idle code.
The information screen shows “Very low refrigerant… A/C compressor off” Could this be the possible cause for a vacuum leak and higher idle issue?
You posted about this high idle problem previously and per forum rules this update should have been placed there instead of as a separate topic. (Topics merged.)
Heard, Thank you.