If your 1996 Chevy Lumina idles fine but at take off begins to stall what could be the problem?

Answer 1

I would first check for vacuum leaks. If the check engine light is on, it could be the TPS, (Throttle Position Sensor). A bad TPS will idle fine, then the engine will stumble on acceleration. But if the pedal is depressed & held in a certain position, the computer will finally figure out that the throttle is open by the signals of the other sensors & then the engine will purr up to it's proper speed. But as soon as you move the pedal again, the computer gets confused again temporarily. The TPS is a glorified potentiometer, (variable resistor), located inside a sealed housing that is mounted on the throttle body. It has three terminals on it, (either two or three of which will be used on any particular engine). To test it, you'll need a VOM, (Volt-Ohm Meter) or a DMM, (Digital Multi Meter). Regardless of which tool you decide to use, you'll need a meter that measures resistance, (AKA impedance) in ohms.

Disconnect the connector at the TPS. Then connect the positive, (red), lead to the center pin of the TPS & negative, (black), lead to either of the two outside pins. Set your meter to measure ohms in the 10K, (10 'Kilo' ohms, or 10,000 ohms) ohms range. Read the meter. Depending on which pin you connected the negative lead to, the meter should read either ~0 ohms or ~5K-10K ohms. Rotate the throttle while observing the reading on the meter. If the original reading was ~0 ohms, then as you rotate the throttle, the reading should increase in value until you have rotated the throttle all the way. At which time, the reading should be ~5K to 10K ohms. If your original reading was ~5K to 10K ohms, then the opposite should occur, the value will fall to ~0 ohms as you rotate the throttle, until you have rotated it all the way.

If these readings don't happen, in either direction, (i.e. up or down in ohms value), first try to adjust your meter to a higher range, (i.e. 100K ohms), then repeat the test above. If you still don't see a change in value on the meter, then try to connect the positive, (red) lead to one of the end pins, (with the negative still attached to the other end pin) & try the whole thing again.

If after all of these tests you still don't see a change in resistance when you rotate the throttle, or if no matter where you connect the meter leads, you read infinite, (or very high and unchanging), ohms value on the meter... this means that you have a bad TPS.

A TPS sensor can be an expensive dealer item, (~ $60 - $100), so what I did with one that I had go bad, was to cut open the housing, (where the glue holds the two halves of the housing together), and then re-solder the broken connection inside, (if possible), & then glue it back together.