I have a 1995 Z28 with 138k miles. I recently installed LT's and Purple Hornies glasspack mufflers w/no cats. Talk about one mean sounding LT1. I have recently put a new cap/ rotor kit on, as well as new plug wires. I didn't replace plugs because they are less than a year old. Over the past 2 days the car has been idling rough after warming up. It spits and sputters, and almost feels and sounds like it's not firing on all cylinders. Also for no reason the cooling fans come on and set a check engine light. I have tried and have had several guys I work with try to pull the codes, but with no avail. I cannot afford to send my car to a Chevy dealer or shop to have the problem figured out or resolved. I have pulled the wires off the plugs one at a time and used a nanoplug to test, and they all fire properly. I have seen several posts with the same problems. If anyone knows what could be causing this, please post a response. This is a MUST repair ASAP!!!

 

the fans usually come on when the MAF goes bad..or if you unplug it. Also..check your plugs for cracks in the ceramic. hairline cracks can cause it that to happen and last but not least the opti-crap...that could be bad as well. when my opti went bad..i replaced the cap and rotor and it didnt help at all..i had to replace the entire thing.(just a thought)

 

my plug wires have no cracks or anythin...they are brand new. When I unplug MAF the car shuts off. The weird thing about this problem is that it is all on the passenger side. to me this would tell me the optispark is good, plus the fact that I have pulled the boots off the plugs one at a time and they all arched exactly the same. My problem is that I cannot afford to take my car to the shop to have this figured out.

 

Did you turn off the lights to check for arcing around the plugs?

Since you put on new headers perhaps you have a leak around the manifold that is letting in air causing a false lean condition.

What codes does the ECM throw?