Just can't figure out whats wrong with my s4 n/a. First of all i have tried adjusting tps. then idle screw from directions from the fsm but I just can't get that bouncy idle @ 1500 rpm. and other times it sits at 2000 rpm or 1800rpm
Sometimes it will backfire ALOT during decel and during acel engine will cut at some rpms
Other times (mostly) it will stall all the way up to 3 or 4 hundred rpm and sometimes die if I don't tap on the gas pedal.
I have tried two diff tps sensors and two diff TB's and same stuff happends.
I have checked for air leaks all around the upper and lower intake manifold but can't find any.
Is there anything tht Im missing, please help!

 

Once you re-set the TPS, did you go back and re-set the idle speed? Short out the initial set connector. Crank the engine and turn the idle screw on top of the TB until you get 750. All this done with the engine up to normal operating temp. Make sure you remove the short from the initial set connector when you're done. Bouncing idle usually means an out of adjustment TPS.

 

did u bother to check and make sure the tps is even good?

 

^^yes and yes, the tps is good is at 1k ohm at idle and 5-6 k at wot. while trying to set idle speed the screw doesn't make much of a difference, it only changes the rate of the bounce and thats just alittle bit.

 

are you positive there are no vacuum leaks?

 

Textbook vacuum leak. Is there are crack in the black tube leading from the AFM to the throttle body?

 

^^no, its very tight