Okay guys, I need a little help here. Here's whats going on:

I overrevved my car to 9913 (missed shift) and since then it's been running like crap. It seems to be missing on at least 1 cylinder. It ran, but not very well.

It started making a tapping sound audible from the head. The tach will also go crazy, like shooting back and forth from 1k-5k at idle even.

I thought it was a disutbutor problem. Used a good one and it didn't go away.

So this is what it does when I start it when it's completly cold and the ECU is reset:

Starts up. Runs fine for a few minutes until it almost warms all the way up. Then the tach will start jumping, like little hitches from 600-1000 every 10 seconds. The engine speed wont change, but the tach will twitch. Then after a few minutes it will audibly start missing and idles bad. Then the tach will really go crazy, like up and dow from 1k-6k. But the engine speed doesnt change. Then I'll shut it off. Then if you try to start it, it wont start unless you reset the ECU.

Any help?

 

Pull the head and look at your lovely bent valves.

Could have also put a hole in the piston.

Compression check and Leakdown.

 

You've got bent valves.

Best case scenario is that you only bent a valve or two. Worst case scenario is that you bent all the valves, damaged the head, and dropped some metal bits into the block.

I would definitely not recommend continuing trying to run the car in that condition - you could drop a valve into the combustion chamber which will damage the cylinder wall and/or pistion. A leakdown test will help tell the extent of the valve damage per cylinder without removing the head. But to really determine the extent of the damage, the head needs to be pulled and visually inspected.

Andrew

 

if compression test/leakdown test give you bad results, time to mess w/ your internals and spend some money...

 

Thanks for the help guys. I've suspected that from the beginning. I still dont know why my tach goes all crazy because of this. My compression test results that I did a week ago were 160, 150, 140, 150. This is up from a month ago which were, 150, 135, 125, 140.

I'm gonna pull it apart this weekend.

Thanks again. I would have responded earlier but I can only post 5 posts per day.