Every time i start my car up in the morning i have to sit and warm it up for like 5 mins. because it backfires very loudly and accelerates bad. then after those 5 mins my car will idle up and down from 1500 to about 1200 rpm until my engine is warm then it drops to 800 rpm. anybody know why this is happening?

 

check your tps or acv

 

I dont think it can be the tps because it stops after a while im thinking it might be the BAC. and do you think that removing the air pump had anything to do with it?

 

unhook the bac and see if anything changes.

s4 or s5?

 

I'm having the same problem, but I was leaning towards the tps because it didn't start doing this until I changed the TB.

 

my car is an 86 S4. ill try disconnecting the bac and see what happens

 

well i tried disconnecting the bac and it does the same thing basically so im assuming the BAC is bad

 

i disconnected the bac and the car did the same thing so im assuming the its the BAC that is bad