Hey guys, so i searched the forums and couldnt really find anything relating to my issue. Ill start by saying I have a 1991 firebird 3.1L with the auto tranny.

I noticed that my idle in gear is very low (ranges from 500-650 RPM), when the idle gets to around 500 or 550 the car begins to shake, but it doesnt feel like its about to stall out.

basically im wondering what everyone's idle RPM is in gear.

Also, for those with an auto tranny, when you guys are slowing down and downshift from O/D down to second and then first does your car make backfiring sounds?

Thanks!

 

Idle in gear when the car is warmed up is usually arround 750-850rpm. 500 Rpms is definitly low but then again I wouldnt trust your tachometer to much as there usually off(under) what the real rpm is.