LT1 hesitation at cruise speed

[Red VelVette]

I just noticed a very minor hesitation or miss about every 8-9 seconds when cruising on the highway in my 92. It lasts for way less than a second and is easy to miss it as it feels like hitting a very minor bump or seam in the road. It is not enough to really effect power but is a perpetual rhythmic "pulse" that I can count if I focus on it. It is not enough for a passendger to detect but I can feel it in the driveline.

Any ideas on what may be happening?

 

[G Winter]

It could be a plug or a wire.
Glenn

 

[Red VelVette]

I had thought of that first but wondered why it would only be every 8-9 secs and so perfectly rhythmic.

 

[tigmaned]

i have never done it with a V8 but i did it with a 4 one time that was doing the same thing. with it running i took one wire off at a time. 3 wires i took off made the little 4 bange run worse, but one wire i took off didn't. i pulled that plug and it was all black. but this my not work with a miss? if you haven't did a plug or cap rotor and wire change in some time i would try it, and also look for a vac leak some were. good luck in the search!

 

[G Winter]

A bad plug or wire can give a miss at above idle rpm that you don't always feel . with and injected system you could even have an injector issue. On my L98 I had two bad injectors , it didn't always miss. The ohm reading on them was low[which indicates a short and reduces the power of the coil] so it didn't get full shot of fuel. The thing that clued me was that it ran better cold when then warmed up. The closed loop runs rich so it made up for some of the lean injectors.

Glenn

 

[DMGroh]

I have a '96 LT1 and have a similar miss, only mine is intermittent and is getting more noticeable. Usually at low speed (20-50 mph), sometimes when getting lightly on the gas, other times while steady throttle. No noises, backfire or other drama, just sudden loss of power for less than a second. The only other thing that is coincidental is my digital temp gauge is starting to become erratic with widely fluctuating readings. But there is a different sensor for the engine computer, so I don't think that is causing the miss.

I'm not getting any codes or check engine, but I was wondering; Can a fault be stored without the check engine lite coming on?

 

[DMGroh]

Seems there are 2 types of "misses"; one at cruising speed & steady miss, the other intermittent at low speed lightly adding throttle.

For the high speed miss, I ran across this thread...never heard of "cam surge" before, but maybe it will help shed light on your situation.

http://lt1tech.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=6;t=001747#000003