Hello,

Im new to the camaro scene and would really like some advice. Last week I purchased a 1994 Z28 with 68,000 miles on it. The car is stock as of now, other then Flowmaster exhaust. After the car is running about 30 mins or so. It begins to miss alot and idle very ruff when sitting still if the car is in gear. The check engine light never comes on. Car had a full tuneup 3 months before I purchased it. The temp was a little warm so I replaced the thermostat this morning. It's still doing the same thing. Has anyone ever had this happen before? Any help would be greatly appreciated..thanks

Chris

 

Check for spark plug wires arcing; easiest way to to let the car idle in the dark, look for arcing between the wires and the block/exhaust manifold. You might also change the fuel filter. Do you know the previous owner; are you sure the car had a tune-up 3 months ago? What was done during the tune-up?

 

thankyou for your response, unfortunally no his tuneup was just word of mouth, he said plugs, wires pvc ect...so if a plug was arcing why would it only do that once the engine was really warm? im very curious..plus a little nervous, im hoping this dosent turn into a expensive fix.

 

I think you need to have someone diagnose it. Off the top of my head it sounds like it could be an intake leak which is a fairly common occurance.

 

Since you don't know that it was really tuned up, I'd pull a couple of plugs to verify that they're relatively new and inspect the wires to see if they look new. How does the air filter look?

Usually if the intake is leaking you'll have oil on the back of the intake manifold. When the engine is cold, run your hand along the back of the intake where it meets with the block. If you hand comes back oily, you have an intake leak.