Focus Fanatics - View Single Post - Very High Idle - Throttle Body and TPS sensor questions
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Old 01-18-2013, 02:49 PM   #8
rycodge
Focus Rookie
 
Join Date: Jan 2013
Fan#: 108520
Location: Portland, OR
What I Drive: 2003 Blue ZX3

Posts: 19
FF Reputation: 1 rycodge Good Standing Member
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So I've replaced the IAC with a new valve. After cleaning up the old one, the plunger was very stiff to move and hooking up the old IAC to a 9V to actuate the plunger didn't do the trick. I later stepped up to 12v 2amp current from the battery charger to test and no dice.

Problem is the car is still idling very high between shifts and it only calms down when the car is not moving for about 10 seconds. I disconnected the TPS just to see and the car was exhibiting the exact same problems. No CEL code though??

One interesting thing the car was is doing after replacing the IAC valve is somtimes the car will WANT to fall down to like 1000 rpm when I depress the clutch and it will "bounce" between 1000-2000 RPM a few times, then stay up around 2200 until I come to a complete stop. It doesn't always do this, but it seemed to be 1/10 times I depressed the clutch while driving down the road.

How does the engine even calculate the proper throttle response when the TPS is disconnected? Does it use the O2 sensor and MAF to guess what the air / fuel should be?

Do you think I may have replaced my bad IAC valve with a defective valve?

Any other sensors that could be causing this? I've tried two different tps's.

Maintenance I've done to the engine so far:

New crank sensor
New pre-cat O2 sensor
New passenger motor mount
New air filter
New spark plugs + wires + coil pack
New PCV valve - vacuum line looks good.

This is the last engine issue I'm trying to sort out! It's driving me mad lol.
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