1998 Chevy Venture Idling problem.?

Question

Today, the check engine light lit up on my 1998 Chevy Venture. The problem is it shakes while it Idles. When you are driving it doesn't have this problem.

For this reason I narrowed it down to the Throttle Position Sensor (TPS). But when I tested it, the Voltmeter came up with .6V at idle and 4.5V at full open throttle.

The book I am using says approximately .5V for Idle and 4.5V for full throttle, is this .1V deviation in the idle voltage what is causing my problems?

If not can anyone help me??

I don't want to buy a $30 sensor if I don't need it.

Thanks!

Answer 1

I would say that the voltage variation is not significant. However, you need either an oscilloscope, or an analogue volt meter with a needle, not digital. I'll assume you don't have a scope. In addition to the voltages at idle and at full throttle, using the meter, slowly move the throttle from idle to full and back again. You can do this from under the hood or with someone working the accelerator pedal. You should see a nice smooth transition from the low to high and back again. You can check this using resistance as opposed to voltage as well. The car does not have to be running or have voltage to check this using resistance. Any jumping at all and the TPS should be changed. It should be perfectly smooth. You can buy an analogue meter at Radio Shack for under $10.

Answer 2

egr valve or vacuum leak or something alot more serious.