The civic runs great, starts good and idles good. once the car warms up it rests at 900rpm. If i hit the gas pedal at idle it revs up and then drops to about 400rpms and recovers. Drive it for 20mins and do a pull on the highway through any gear and let off and the idle falls straight to die or stumbles for a second then dies.

00 si civic built bottom end
.58 trim full race ram horn manifold
tial wastegate and bov

 

The exact thing happened to my stock JDM ITR swap installation. It turned out to be the throttle cable idler stopping screw need to be adjust.

 

Same thing happen to me a few weeks, to my civic ls/vtec turbo.

Whenever a made a pull and release the throttle the car died.

I cleaned the IACV and the same, after some tests, buy a used IACV from eBay and viola !!

Hope this is your case too.

 

Could be many things. Do you have a really light flywheel ? IACV could be dirty, idle adjustment screw is not set correctly on he throttle body. If its tuned it could be that your fuel and timing compensations are wrong in the parameters as well

 

I think its your IACV theres a thread on how to clean iton here somewhere, but its so easy i just take the two bolts off pull it up take out the two coolant hoses and plug them quick and spray the valve with brake parts cleaner and let it drain and reinstall.

 

Ill try and clean the iacv valve. I tuned the car just on the street so he can use the car to get around. The car was tuned professionally, but somehow he erase the hondata tune, and the car would not start. For now i just put a b16 map added my boost table and retarded the time 1deg per pound of boost with an af ratio of 11.5to1 to be safe. He has a bonus coming up and plans to get it tuned then. he just needed something to get him to and from work, plus make sure every thing is running properly and working like it should. once you take it to get it tuned they change you stupid amounts of money to fix something small if its not right.

 

You should run a AFR or 13.5 to 14.5 at idle and part throttle 11.5 to 12.5 in WOT/boost. To be safe and run the motor properly.

 

I should have been clear, I tuned it to 11.5 under boost and 14-13 during idle or cruising speeds.

 

Sounds good.