I just finished putting in a new throttle body and plenum on my car. everything seemed to go in fine but when i run my car it idles high, and when i rev it, its slow to coming back down to idle rpms. When i turn it on its starts off at 2K rpms then drops to about 1100 which is still high. the throttle plate closes all the way on idleing so theres no extra air coming in. I had a similar problem before but was fixed when i changed the idle control valve so i doubt its this valve because its brand new. Is there anything else i should be looking for? I'd appreciate any help i can get because im trying to finish tonight because i have an appointment to have my car tuned tomorow morning. thanks

 

thats a common problem with bigger throttle bodies. did you go with a 70mm or 75mm? it could be your throttle position sensor too. Mine starts off at 1500, runs at about 1100 then drops down to 800 as well. if yours doesnt drop off from 1100, im guessing its throttle position sensor. you can also adjust it.

 

i went with the 75. How would you adjust the tps, and is this somthing that can be adjusted through the ecu when i get my car dyno tuned tomorow?

 

they can adjust your idle through the dyno tune which is what i would let them do. just mention your car idles at 1500 then drops down to 1100 when its on the dyno.

 

My guess would be a vaccuum leak.

Make DOUBLE sure that everything is TORQUED to spec. Not tightened til snug and then turned a quarter turn. TORQUE it. If it doesn't go away after that, then you'll need to check other things...