biederboat

Somehow I knew this would happen. Daughter's 98 EX 5-spd CEL went on a while back, P0505 (IAC fault). I researched, cleaned out the valve (a few times), no help. The car came with a cold air intake, I installed a factory air cleaner assy. As she just got back from college, I finally installed a new IAC valve. CEL back on!

Aside from the CEL being on, the other symptoms are: When decelerating, engine will idle down, bounce up a bit, then settle to 1K on the tach. It will occasionally "buck" when accelerating. When I've cleaned/changed the valve, there has always been coolant at the valve. Also, when I disconnect the air intake hose as the throttle body and put my finger over the intake to the IAC, it idles down nicely (did this with original and new valve). Bottom line, repalcing the valve doesn't seem to have helped a darn thing.

Any final things to try before I give up and go to a shop?

Thanks,
Biederboat

gearbox

iTrader: (95)

sounds more like a bad tps sensor. i would look for a whole used throttle body to swap in. usually $50 on ebay. and be sure to get a 5-speed version. if rpms bounce around or go up on their own, its a tps issue. iac issue only causes idle drop and stalling. usually iac sensors do not go bad, they only get clogged.its much more likely for tps to go out.

biederboat

Well, I just looked online, TPS's look to be around $40, is there any reason why I shouldn't just do that as opposed to the used throttle body? Does the sensor actually move the butterfly or something else that would cause the amount of air flow (or something else) to change? When I heard "sensor", I think of something that just measure, doesn't actually move anything.

Thanks,
Biederboat

CrewChief

iTrader: (1)

The TPS regulates the injector signalalong with the MAP sensor. If its faulty it could be adding or pulling fuel at the wrong times. Its an easy change.

gearbox

iTrader: (95)

tps is easy to change, but hard to calibrate the voltage. swapping in a whole piece is much easier and faster. it tells the ecu how far open the butterfly valve is. on an auto trans it can cripple the car if not working properly.