Needing a couple of answers

[kowalski vanishing point]

I just replaced the two intake manifold gaskets on my '97 GTS.

There was a big improvent. The car idles at its normal RPM more often (about 80% of the time) and when it does the fast idle thing it only does it at about 1100 RPM instead of the previous 1250-1500 rpm. (Which it was doing about 66.6667% of the time previously).

BUT

it still has that high idle gremlin. I have replaced the air cleaners, the idle air control motor, spark plugs and wires, and PCV valve, (and the intake manifold gaskets) in the last two months.

When idling in neutral if it is at 600 RPM or so it will speed up a few times like I was barely blipping the throttle then blip up one final time and stay at about 1100 RPM. I'll drive off and for a few stops it will be at 1100 RPM at idle and then mysteriously I'll come to a stop and it will be idling at 600 again.

NOW

the last time it started its nonsense I happened to be in the driveway. I did a number of things under the hood but found that IF I grabbed the drivers side throttle body linkage and pushed it the dirction of shutting the throttle valve THEN I would be able to keep the car idling at 600 RPM. Let go and back up to about 1000 RPM.

I've allready put a .003 inch gap in between the set screw and the stop that controls the passenger side throttle plate.

Should I

1) adjust the idle speed set screw on the drivers side throttle body, risking a slow idle 80% of the time

2) replace the throttle postion sensor

3) replace that whole throttle body because maybe the shaft the pivots the throttle plate might be slightly worn at the pivot points (and how would one check? and does this ever happen?)

4) loosen the throttle cable just a tad

5) call my local Catholic Priest and perform an exorcism.

6) any other ideas?

For the first time in 3 months I feel like I'm close to getting this car running right, I'd like some advice so I don't screw it up worse.

 

[2charmed]

I have heard the throttle cables need adjustment from time to time. You might check with Jon B. at the parts rack or Dan Cragin
up in Santa Monica.
Good luck,

2Charmed

 

[phiebert]

My two cents would be to start with:

"2) replace the throttle postion sensor"

It sounds like by grabbing the throttle linkage and forcing it down you might be getting it to a "clean" spot on the throttle position sensor making it realize that its supposed to idle. On my '94 I can make the same symptoms happen if I ratchet the driver side cable too much tighter than the passenger side. This causes the car to think that the pedal is slightly pushed down. I'm not sure if that makes sense.

Good luck, it does sound as if you are close.

 

[kowalski vanishing point]

Thanks.

I may just change the throttle position sensor on principle (the principle that I've just about changed everything else).

I've heard that TPS's can be sensitive to water and this car has seen alot of rain and some snow driving as well as some engine powerwashing.