Engine is Surging Intermittantly. Causes?

[RickCoMatic]

The RPM's are surging on the V6 3400 SFI Engine in my '04 Monte Carlo. I thought this was related to my pllaying with the Cruise Control, the other night, But, my wife said she experienced the condition this morning. The Tach runs-up to the limiter and backs-off.

Recent work: New Air Filter replacing seriously clogged one.
Front 3 Spark Plugs replaced with Champion Platinum Plus replacing what look like Iridium Type Plugs (Very thin ... needle-like electrode).

What should I be looking into please?

The Old Man from Massachusetts,
Rick Massey

[IsaacHayes]

Well I don't know about champion platinums.... But I do know stay far far far away from bosch plugs.

The plugs you *should* be running are ACDelco's, in all 6 cylinders. Yes the back is a pain but you just do it by feel it's not that bad. Remember after you have the boot off to blow some air around the plug so when you take it out dirt doesn't fall down into the cylinder.

Read this http://www.60degreev6.com/showthread.php?p=328559
I would get known compatible plugs in ALL cylinders before you try to diagnose the surging.

Do you mean by the tach running up that the engine races up that high or the needle just moves around? I would check the charging system if the needle is going bezerk. A dying alternator or low voltage can cause weird gauge abnormalities.

[RickCoMatic]

No. For me it was a dangerous situation. I engaged the Cruise Control to see if it worked. It seem not to cancel after I shut it off. Then the Car accelerated to 55mph and I couldnt cancel the Cruise with my foot on the brake. I was worried about overheating the brakes and just reached over and shut off the ignition hoping for a reset. No. Did that three or four times. Put on the flashers and pulled over with the ignition OFF. Started the engine and the rev's seemed to go and hit the limiter and back-off. Killed the ignition and sat there for a few minutes and tried her again. Seemed to act normal from there on in. This was BEFORE I did the Plugs but AFTER I replaced a very badly CLOGGED Engine Air Filter. I don't know what its doing right now. Tomorrow, I'm going to investigate a Surge (or Hunting) that the wife experienced this morning on her way to work.

[IsaacHayes]

Well seems my reply was lost.... I said to check the cruise maybe the cable is stuck holding the throttle open, bad cruise motor? Maybe it's got the throttle partially open still causing the IAC to make a surge as it tries to reduce the idle.

I would disconnect the cruise cable until you get it replaced or looked at. Sounds dangerous don't use cruise until it's fixed.

Also I would go with AC delco plugs and replace all 6 and then go from there. Not sure how well champions work in our cars or if those you got are the right heatrange/etc. Stay far away from bosch. AC delco all the way.

read this http://www.60degreev6.com/showthread.php?p=328559

After you have all 6 sparkplugs taken care of, and the cruise cable disconnected from the throttle linkage let us know if you still have a surge and we can go from there.

[RickCoMatic]

I lubed both the Throttle Cable and the Cruise Control Cable and haven't had a repeat of the aforementioned surging. But, there are also new Plug Wires and Plugs now along with a brand new Air Filter so I'm thinking the variables causing the problem got corrected.