1996 Chevy Corvette Oscillating Idle

LT1 OWNER

MEMBER
1996 CHEVROLET CORVETTE
V8
2WD
MANUAL
10,000 MILES

When my LT1 engine get to temp, the idle raise to 100-2500 and oscillate randomly within that range. The oscillation is not really fast and again it is random within the range, not a set pattern of increase/decrease.

I'm thinking its either the IAC valve or the TPS is bad. However, they are both expensive parts so I don't want to buy one and it not be the problem.

Thanks.

1 Reply

ERNEST CLARK

MECHANIC
1,730 POSTS

Is your check engine light illuminated? If so, have it scanned at AutoZone. It's free.

Then check all of your hoses for a vacuum leak. If you find any, replace them.

If not, and you're handy with a multi-meter, then you can test the T.P.S. As follows:

Unplug the connector to the sensor.
Turn your ignition to the "On" position. (DO NOT START)
Ground the black lead of the meter to the engine block.
Probe the terminals inside of the connector with the meter's positive lead.

One of the terminals should read "5-volts". This tells you that the computer is sending it's reference voltage.

Next:

Probe stick both of the meter leads into the terminals on the T.P.S. Record the reading.
Move the throttle until it's half-way open. Record that reading.
Move the throttle until it's fully open. Record that reading.

Take your readings to AutoZone and ask them to look up what the specs are for your T.P.S. If they are out of specs, then you know it's bad.

If not, check the IAC valve for any signs of a vacuum leak. If there is, replace the hose. If it isn't, you can ask AutoZone or another major parts store if they are equipped to check that sensor. If they aren't you'll have to take it in to get looked at.