Low rpm surge, then drop, then surge...

[henson]

Hello, my 95 w/2.2 and 50K at low rpms surges then drops in 2 second cycles? Accelerates and decelerates fine and even cruises okay, but what gives with this surging? Any help?

[dmbrisket 51]

is it a rough or smooth surge? my old truck (91 chevy 1500) does it all the time cold as a smooth cycle, its not a big deal, annoying but not a big deal, try checking filters and injectors

[BlazerLT]

Clean your IAC with throttle body cleaner and a tooth brush and reinstall.

Idle will be back to normal.

[henson]

Cleaned it and problem is still there? replace 02 sensor next?

[sector95]

Originally Posted by henson

Hello, my 95 w/2.2 and 50K at low rpms surges then drops in 2 second cycles? Accelerates and decelerates fine and even cruises okay, but what gives with this surging? Any help?

Some thoughts....

Engine Light on?

I would see if any local auto parts shops can download trouble codes as a free service..... just because the light is not on doesn't mean there isn't some trouble brewing behind the scenes.

Fuel filter.... ever replace it or is it original? If it's restricting the flow it might cause erratic operation of the injectors at low rpms. Injectors need proper fuel pressure to operate correctly

Injector cleaning... ever have it done professionally? Poor injector spray patterns can cause erratic engine operation. A "poor mans" attempt: get some Chevron Techron and double (or greater) the dose. Usually the bottles come in 12 and 20 gallon doses: put two 20 gal bottles in a full tank or one 20 gal dose in a half tank. This stuff works; I've used it with great results... and it's expensive (about $9 for the 20gal bottle); don't waste your time with the other cleaners. If the symptoms seem to improve, do the double treatment again.... and again until the problem is cleared... or have it done by a pro.

Mike