1992 6g galant automatic transmission Idle problem.

[wilson24p]

hi guys. i have 92 6g galant automatic which we overhauled last two weeks ago. the problem is when in park/neutral mode it idle normally at 900 rpm but when i am in drive mode and reverse the rpm goes down to 650 rpm and it goes down as i turn on the a/c.i've check all the hoses for vacuum leak and its all ok. i hope someone can help me what to check with my car. thank you and godbless.

 

[89Mirageman]

Have you tried to adjust the BISS? Also your ISC could be bad.

 

[wilson24p]

ok im trying to adjust the biss screw to what rpm? its the isc is the idle stepper motor?

 

[89Mirageman]

Yes, the idle stepper motor. Sounds to me like its not working. It's supposed to adjust and let more air in once a load is put on the engine.