LT-1 Lunging at Idle and Sputtering
#1
LT-1 Lunging at Idle and Sputtering
Well, for a change, I have a question...
I'm looking at buying a 92 Vette, 95k miles,withan LT-1 (first year available in the Vette). I figured it would be safe to ask here since the engine is pretty much the same as the Camaro, other than factory h.p. rating (300).
In park, it idles fine. When put in drive or reverse, the engine idles a little rough, and makes the car jerk and try to lunge. I can also feel the idle start to speed up a little and make the car creep more. Then when put back in park, the rpm's jump up to 1500, then go backdown right away to around 800-900. I disconnected the Idle Air Control motor, and then it didn't act up. But, is it the IAC, or something else that is controlling it? And what is making the rpm's climb only while in gear?
Another thing it does, is the enginesputters when I rev it in neutral, and if I take off from a standing start, light or heavy gas pedal. And it continues to sputter throughout the upper rpm's. But, I'm thinking that may be a different issue, possibly a needed tune up? No idea if the plugs/wires have ever been changed either. And it sure acts like an ignition problem to me.
The water pump isn't leaking, and the opti-spark is bone dry. The enginedoesn't blow any smoke,black or white. And no SES light either.
I'm curious if anybody else has had these same symptoms, and what was the cure? I've had an LT-1 before in a 96 Z28, but never had these issues. I'm really interested in this Vette, it's a convertiblein decent shape,and only $5,500.
I'm looking at buying a 92 Vette, 95k miles,withan LT-1 (first year available in the Vette). I figured it would be safe to ask here since the engine is pretty much the same as the Camaro, other than factory h.p. rating (300).
In park, it idles fine. When put in drive or reverse, the engine idles a little rough, and makes the car jerk and try to lunge. I can also feel the idle start to speed up a little and make the car creep more. Then when put back in park, the rpm's jump up to 1500, then go backdown right away to around 800-900. I disconnected the Idle Air Control motor, and then it didn't act up. But, is it the IAC, or something else that is controlling it? And what is making the rpm's climb only while in gear?
Another thing it does, is the enginesputters when I rev it in neutral, and if I take off from a standing start, light or heavy gas pedal. And it continues to sputter throughout the upper rpm's. But, I'm thinking that may be a different issue, possibly a needed tune up? No idea if the plugs/wires have ever been changed either. And it sure acts like an ignition problem to me.
The water pump isn't leaking, and the opti-spark is bone dry. The enginedoesn't blow any smoke,black or white. And no SES light either.
I'm curious if anybody else has had these same symptoms, and what was the cure? I've had an LT-1 before in a 96 Z28, but never had these issues. I'm really interested in this Vette, it's a convertiblein decent shape,and only $5,500.
#3
RE: LT-1 Lunging at Idle and Sputtering
My experiences may not directly help you other than to broaden the realm of possibilities. My Z28 ran like crap while my son used it. It turns out he was putting 87 octane gas in it, in spite of the fact that I showed him the manual and pointed out that a P series engine needs 91 octane. The ethanol being put in the gas in my are made matters worse. Once we got the tank back to 91 octane, things were fine.
#5
RE: LT-1 Lunging at Idle and Sputtering
ORIGINAL: ledzeprokon6
had this problem. for me my iac plug was unplugged. check it
had this problem. for me my iac plug was unplugged. check it
#6
RE: LT-1 Lunging at Idle and Sputtering
Sounds to me like the idle problem is probably an issue with the IAC, the sputtering problem I would say plugs, wires, fuel filter, general tune up sorts of things. How many miles are on the car? Even bone dry Optisparks have a tendancy to die around 100,000 miles.
#7
RE: LT-1 Lunging at Idle and Sputtering
It has 95k miles, so yeah the opti is on borrowed time. If the optispark is causing a misfire, wouldn't it throw the SES light on, or not necessarily?
Another possibility that I'm finding is a vacuum leak. Either a vacuum line, or a gasket/seal/o-ring.
Another possibility that I'm finding is a vacuum leak. Either a vacuum line, or a gasket/seal/o-ring.
#9
RE: LT-1 Lunging at Idle and Sputtering
ORIGINAL: Camaro 69
It has 95k miles, so yeah the opti is on borrowed time. If the optispark is causing a misfire, wouldn't it throw the SES light on, or not necessarily?
Another possibility that I'm finding is a vacuum leak. Either a vacuum line, or a gasket/seal/o-ring.
It has 95k miles, so yeah the opti is on borrowed time. If the optispark is causing a misfire, wouldn't it throw the SES light on, or not necessarily?
Another possibility that I'm finding is a vacuum leak. Either a vacuum line, or a gasket/seal/o-ring.