surging

[89blkvet]

I have an 89 vette, and when i am running at a steady speed, either fast or slow, the car seems to surge. The RPM's drop and increase enough where you can feel it. Under acceleration, there is no sign of the sputter. also at idle, it seems to jump between 500 and 700 rpm. Any suggestions?? Thank for the help

 

[jpanek]

Check intake manifold and vacuum hoses for leaks. Check O2 sensor waveform for sluggishness. Put Techron in the gas tank to clean the injectors.

 

[Tonylong]

I also have an '89 with a similar sympton.
When I am stopped with the brake depressed, the engine running, the
auto trans in drive - such as at a stoplight or during a parking action -
I occasionely get a sudden acceleration, Enough to cause the car to lurch forward,
and a panic jamming of the brake pedal, Once I collided with the car
ahead, fortunately no damage.
I used to think it was me accidently pressing the accellerator, but I've
been careful to watch what I'm doing and I'm sure it's not me.
Has you had this sudden forward lurch happen ?

 

[89blkvet]

Would it be safe to use card cleaner to help me find the vacuum leak??

 

[caddy]

What is card cleaner? :confused

 

[jpanek]

I think he meant carb cleaner, spraying along joints in the system so that it temporarily sucks in solvent instead of air. Not sure if it's safe or not. I've noticed there is a throttle body cleaner that is different in some way than carb cleaner.

 

[bradfordsvettes]

does this surge with the ac off . if the ac has a low charge the ac compressor shuts off and on with the cycling switch and it feels like a surge at a constant held speed only my 2 cents steve

 

[89blkvet]

It surges even when the AC is off. It only seems to surge when I am on the freeway going above and maintaining 65-70 mph. Once in a while in town, but mostly higher RPM. I actually sprayed the carB cleaner around a few of the vacuum hoses, but there was no jump in RPM

 

[vettenick]

Use propane (without it being lighted) if you're trying to find a vacuum leak. It's cleaner than spraying carb cleaner, plus you run little of a chance of a fire.