I noticed while checking TPS that the throttle valve will open all the way up when the pedal is pressed but the car is off. With the car running, the throttle valve barely opens even with the RPMs at 4000--whats going on?

I don't understand what you are asking. When you press on the accelerator pedal, the cable makes the throttle plate move, at all times.

If your engine is running at 4000 rpm without much of a throttle angle, and no foot on the gas, you have other issues.

Please specify year and engine, please.

The accelerator pedal is the only thing that controls the throttle valve. With no load on the engine (running in neutral) it doesn't take much of an opening to allow the engine to rev all the way to redline.

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Rod Schneider, Woodstock, Ga.
White 88 GT :)

'85 4 cyl: How does the throttle valve know if their is load or not. If I put the car in drive while holding the brake and rev it, will that place a load on the engine and open the throttle valve then. I can't test this for a few more days but popped into my head.

Re-read the replies. The throttle valve is connected to the gas pedal by a cable. There is no electronic link. You press the gas pedal, the trottle opens. Period. Doesn't matter what engine speed, gear, or if the engine's even running.

I don't think I understand what your concern is. If the valve moves from closed to full open as the pedal is depressed (check by looking at it with the engine off), and isn't sticking or binding, then it's working like it's supposed to. Are you having idle problems with this car? If so, and the valve is working like I described, then your problem is either a vacuum leak or an idle air controller problem.

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Rod Schneider, Woodstock, Ga.
White 88 GT :)