1992 Oldsmobile Cutlass Rough idle/engine surge

PETEDURAN

MEMBER
1992 OLDSMOBILE CUTLASS
3.1L
6 CYL
FWD
AUTOMATIC
173,000 MILES

I have been having a problem with a rough idle with vibrations inside cabin that only happens when in gear if put in nuetral it settles. I changed the top torque mounts, cleaned the throttle body changed the IAC and TPS and installed new air filter. The rough idle still exists and after cleaning the throttle body and changing the IAC and TPS the engine surges when coming to a stop maybe around 10 to 15 mph until stopped then the surge goes away. I am not sure what to do next. Please help!

Tuesday, June 10th, 2014 AT 4:15 AM

1 Reply

TY ANDERSON

MECHANIC
719 POSTS

The bottom engine mounts are the usually the ones that break.
Do this in a safe location
Press the brake firmly with your left foot (apply the parking brake also)
and with the transmission in drive and the right foot press the gas pedal quickly & release. This loads the engine mounts and if the mounts are broken will cause the engine to jump or create thud noise/feeling. Do above procedure in Reverse also as it will load another engine mount on the bottom.
As for the surge when coming to a stop. See if the engine surges when coming to a stop when you shift into neutral before the surging usually happens and let me know if you can still feel the surge.
Thanks for the question.

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Tuesday, June 10th, 2014 AT 1:42 PM