rough idle like cam
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Teching In
Joined: Jun 2005
Posts: 25
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From: McLeansville
rough idle like cam I have a 2002 trans am ws6 with 49k. The car has long tube headers with cats slp loudmouth catback slp lid slp maf and 90mm throttle body. It has a very rough idle and shakes sometimes so bad the car cut off. The car is running very rich and im getting horrible fuel milage. i have no check engine light, i have replace plugs and wires the fuel pump/ filter new intake gasket new tps new iac new thermostat and new coolant temp sensor have tested the fuel pressure 58psi not sure what else to do the car runs good when going down the road but when u come to a stop and push in the clucth the car drops to about 500rpm then comes back to about 900. Ive been putting seafoam in it for the last 5 or 6 fill ups and nothing. I was thinking it might be a vaccum leak anybody have any ideas?
test your throttle position sensor voltage. if i remember right, it should be around .57v at idle/throttle closed. also make sure that you are at 0% throttle position. you will need access to a scan tool to look at these numbers. once you get it to .57v with the throttle closed you will want to do a tps relearn. this is how: unplug the tps with the key in the off position, now with the sensor still unplugged turn the key to the on position for a few seconds but do not start the car, turn the key back to the off position and plug the sensor back in, now start the car. tps should now read 0% throttle position at idle. this may be an issue with your car but it may also be a vacuum leak as you stated.
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Gonna ttt this, I'm having the same problem. Did the relearn and nothing. I have longtubes and the longer vette O2 sensors and my rears and tuned out. Car drove fine one day and bad idle the next. My car idles around 500 for about 5-10 seconds then picks back up to where it should be. Car drives fine other than the idle though. I have no cats and TSP true duals also. The O2 sensors are maybe 3 months old as well as the plugs and wires.
No I haven't, today I also noticed that it only goes the rough idle sometimes... Sometimes it starts up fine and sometimes it doesn't.
Should I try some of the spray type sea foam to clean my IAC and TB?
Should I try some of the spray type sea foam to clean my IAC and TB?
I have a friend whose car has done this for years.
We have looked at and tried just about everything. He replaced every rubber bit on the car looking for a vacuum leak. Maf, tps, and map are all fine. Pretty much given up on it.
We have looked at and tried just about everything. He replaced every rubber bit on the car looking for a vacuum leak. Maf, tps, and map are all fine. Pretty much given up on it.