throttle won't quite close

[gtroth]

Well, got the 'S' back together after intake work (ISV, TPS, vac lines, throttle rebuild, injecters professional cleaned...). Runs very strong, but the throttle spring no longer wants to pull the throttle all the way to the idle contact switch unless I let up very quickly. It only misses by a hair. Car's almost undrivable this way (stalls alot).

New Porsche throttle spring (different design, same length) - same result. No surprise I guess. Cut a few coils off the original spring, same thing.

With no spring, I do feel a tiny bit of rubbing just as the throttle closes. I am guessing that's the plate rubbing the bore of the throttle body and holding the throttle open. After I cleaned and rebuilt the throttle, the fit was near perfect - no visible gaps. I don't remember the rubbing, just how smooth everything worked. But who knew a little rubbing here would hose me so badly.

To really inspect / correct the throttle on an 'S' is a ton of work (take the intake manifold off again).

Do I have any choices?

[AaronM]

Throttle cable too tight? Happened to my 951 when the throttle cable was pulled too taut.

There should be a small amount of slack in the throttle cable when the throttle is closed. If there's not, it's too tight, even if it doesn't look like it's holding the throttle open.

[944 Ecology]

Your throttle plate has shifted in the bore and is rubbing the side of the bore. It should not be doing that.

Either reposition the plate so it works smoothly, with no rubbing or binding for its entire working rotation, or junk it and get one that works properly.

You're risking not only poor operation, but the safety of yourself and those around you when the throttle jams open and you cannot stop your car.

gb

[bearone2]

make sure the inner bore is clean, i use carb cleaner on a rag with my finger top/bottom, so that when the throttle is released the butterfly closes and isn't binding.

the screw/locknut needs to be adjusted to where the screw just touches the linkage, 1/2 turn tighter and tighten the locknut.

as you move the throttle linkage open, you'll hear a click in the tps.

the tps knows if your accelerating/decelerating and when your at idle and must be adjusted properly.

[gtroth]

Hey - thanks guys.

AaronM - with the throttle closed, its cable is loose. Cables have little friction to feel. In desperation, I dripped a drop fo 3in1 oil into the jacket in an attempt to reduce friction. No help.

gb - thanks for your concern for my safety and others'. The throttle motion is silky smooth until the last hair before it closes, then an almost imperceptible rubbing. If I release the accelerator quickly it will close and the TPS will actuate properly. If I release slowly, the TPS will just barely miss (if I shut the car door, that shock will make it close). While I am not sure I agree that it is dangerous in my case, I do agree that the plate needs to be right. But I don't plan to drive it until I fix it anyway. It's just such a pain on the 'S'.

bearone2 - yup, it's perfectly clean (used carb cleaner and a rag just as you say). Throttle stop seems perfect, and click is convincing (however, I am measuring the switch continuity with a meter at the DME connetor).

So I am heading toward pulling the IM again to have a look, but I don't really know what can shift or what can be adjusted once I get access to the throttle.

Thanks again,

Tom

[gtroth]

Alright, I gave in and pulled the intake manifold off again (it's amazing how quickly things go the second time in two weeks, heh?). I was able to loosen the throttle plate screws and move the plate a touch for zero rubbing (the amount of rubbing to begin with was ridiculously small - similar to the load the TPS switch puts on it). So now the throttle closes properly and the car's idling better than ever (probably the ISV. Or the clean injectors. Or the new vaccum lines...).

Thanks once more.