mugen si

hi. i recently installed an aem air bypass valve on my aem cold air intake on my si. As i did this i also cleaned up the build up in the throtle body with throttle body cleaner. ever since then (about 4 weeks) the car will idle high after driving a few hrs nonstop. the car idles fine when driving around town (let off the gas and the rpms drop to about 7-800), but when im one the freeway for a few hrs...when i come to the first stop light and let off the gas, the car will idle up to 1500 rpms and stay there for 20 seconds or so. Also the temperature is very cold here...less than 30 degrees. i was told by a mechanic that its moisture from the snow..but i installed an injen prefilter over my filter and the problem is still there. I cant find any vacumm leaks and nothing has ever been taken apart suchas the TB or intake manifold. the car has 80,000 miles if that helps. ive pulled the iacv and cleaned it and the 2 holes going into the TB very well..also sprayd the holes before the throttle plate and wiped them. could the air bypass valve be causing this?...maybe its causing the temp sensor in the intake pipe to be getting mixed readings from the cold outside air nd the warm engine bay air?
thanx

Hardedge

It sounds to me like the engine is being cooled too efficiently while driving for extended periods. So when you stop, the IACV is going to idle the engine hard to try to keep it at operating temperature. If that's the case, it's fine.

Crx Jimmy

I just noticed my si does it when its real cold out as well. seems fine

mugen si

"It sounds to me like the engine is being cooled too efficiently while driving for extended periods. So when you stop, the IACV is going to idle the engine hard to try to keep it at operating temperature. If that's the case, it's fine."

Thats exactly what it seems like to me also. i did recently do a coolant flush and replaced the thermostat. it possibly could be that after driving at 70 mph down the freeway for over an hr when the weather is 30 degrees or colder could cause the car to cool down enough to put it into warm up idle at 1500 rpm's. thanx for the help guys!

Hardedge

Just watch your temperature gauge to be sure.

mugen si

ya the temp gauge never falls aftr warm. also in the warm summer months...ive never noticed the temp gauge to rise past normal even with the a/c on. this car seems to run alot alot cooler than my previous cars...although they havnt been hondas. any more input? thanx for the help so far!

mugen si

ttt

greenweeneer

you may want to check your thermostat to make sure that it's not getting stuck open. if you do replace it, use only a honda thermostat. other wise, i'd have to agree with the previously stated theory of an over ly efficient cooling system.