I have been having some problems with a 92 olds cutlass supreme 3.1, about
191k miles on it. The problems do not appear to be caused by the car being warm or cold and don't always appear. I've posted on here and have had some feedback, but nothing has worked that I've tried. Sorry for the length, but hoping that with a better description, someone might be able to "diagnose" my problem without sending me to the mechanic.About 6 months ago I started noticing diminshed mileage. I changed the spark plugs in April. Didn't help the mileage.
In late May, the fuel pump went bad and it was changed along with the strainer and filter.
About 2 weeks later, I was driving down one of the main streets in town and the car died at about 45 mph. It restarted and seemed to run rough after that.
I have since changed the ECM and the IAC and TPS sensors. I changed the MAP sensor last fall. The car still is not running correctly, but the problems are intermittent. I don't hear anything that sounds like a vaccuum leak, but wouldn't rule that out.
I can start the car and sometimes it will idle fine. Other times it will die immediately. It seems that most of the time, I have to press on the accellerator pedal in order to get it to start. Some of the time this is just to get it to turn over (it clicks like it is still in gear and you tried to start it or like the starter solenoid is bad, but neither is the case), other times it will turn over, but not fire until I press on the gas pedal.
There have been times that I start the car, put it in reverse to back out of my parking stall and it will jerk or lurch. The rpm will fluctuate from about 500 to 1250 rapidly while I back out. It will occassionally do this while stopped at a stop light, but not often. Never have noticed in a forward gear except the few times at a stop light.
When I pull up to a stop light, it will often try to run the car at a higher rpm, just over 1k. After being at the light for a few seconds it will drop down to between 500 and 750 rpm. When it does this, it acts as if it is flooding down, then it usually smooths out and runs so that I can hardly tell that it is running. Other times I pull up to the light and no problems, but this is not the norm. And still other times, I let up on the foot feet and it immediately drops rpm and dies.
I've noticed that it is less likely to die with the a/c on. I've even pulled into my parking stall with the a/c running and it doesn't die. I turn off the a/c with the car in gear and it will then die immediately. Other times, I put it in park first and then the motor starts to race at about 1500 to 2000 rpm.
I have also noticed that there are times I will be driving down the highway or a major street (45 mph +) and the rpm will do wierd things. Before these problems started, normal rpm at 55 mph was just under 1500. At 75 mph it was about 2000. Now at about 45 mph (shifting into 3rd range), it runs just under 1500 rpm. If I remove my foot from the accellerator it will jump up between 1500 and 1750. When I'm at 60 mph, it jumps up to about 2000 rpm when I remove my foot. It almost acts like the cruise when I'm driving on a flat road as it will maintain a constant speed and rpm without me touch the gas. Other times, I remove my foot and the rpm drops off normally.
I was told to clean the throttle body. I haven't done this, however, when I changed the IAC valve and have had the breather tube off, it doesn't appear dirty. I was also told to change the oxygen sensor. Another reader said not to mess with it as the problems were immediately upon start up and the sensor only operates after about 30 seconds. Any other thoughts?
It is an automatic transmission with overdrive.
Why would it require me to press the accellerator to get it to turn over? Why does the idle appear to stick or jump up? Is this a problem with the TCC sensor that I've been reading about or something else? Could it be the coils? I personally doubt the latter, but I suppose it is possible. Other thoughts?