[VaSteve]

Sad panda time. I can't figure this out and have been chasing it since the engine came out and went in this fall. This problem *had been* intermittent, but it seems to be more frequent now. Symptoms: The tach starts jumping around and the engine speed changes (note oil pressure gauge as well). The big revs are my right foot. The following has been done:
- tested plug wires (february)
- tested battery (this week)
- tested alternator/VR (this week)
- checked grounds and all
- test for air leaks (December, Matt deMaria, March, GAG)

All those electrical things can't account for the rise in engine speed...it's almost as if it is taking in more air somehow...I can't make any sense of this.

Guess from you are probably better than my guesses at this point. Maybe Crazy Ray's can fix it.

YouTube- 911 bad running

YouTube- 911 bad running

YouTube- 911 bad running

YouTube- 911 bad running

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[tdatk]

Your oil pressure sucks too.....

If it's air, then AAV or decel valve or loose clamp on the housing. Have you checked fuel pressures yet? Have you observed the air/fuel metering plate? Is it seating right?

If you want, bring it by tomorrow, we'll figure it out.

[VaSteve]

Fuel pressures were tested at length last fall....not lately. What's wrong with my oil pressure?

[tdatk]

Originally Posted by VaSteve

Fuel pressures were tested at length last fall....not lately. What's wrong with my oil pressure?

Nothing.... just messing w/you.
What ignition system are you on?
Is the O2 sensor hooked up?

[tdatk]

My way of starting on this would be to disconnect /bypass everything except the basics to see where baseline is ,then return each one at a time.

[VaSteve]

O2 sensor is not hooked up. MSD ignition. I had thought it was the MSD flaking out for some time and was planning to pull it out and send it for testing. (I have started melting rotors after flawless performance for 5 years). I can't see how the MSD flaking could affect the engine speed but I also don't see how an air leak or anything could show up that dramatically.

It doesn't make sense.

[tdatk]

Hmmm melting rotors...might be a clue there....
O2 effects the frequency valve, unhooked is fine unless you doing emissions. I would suspect the MSD.

[tdatk]

Is it pinging or knocking when the surges occur?

[VaSteve]

Originally Posted by tdatk

I would suspect the MSD.

I have suspected it for a while. I have an open RMA with them, I wanted to rule out the charging system first. So, having eliminated that, and the fuel/air mix, fuel pressure (I could test this again), air leaks...it's the last thing, right?

Originally Posted by tdatk

Is it pinging or knocking when the surges occur?

Doesn't appear to be. What would that indicate?

[tdatk]

Originally Posted by VaSteve

I have suspected it for a while. I have an open RMA with them, I wanted to rule out the charging system first. So, having eliminated that, and the fuel/air mix, fuel pressure (I could test this again), air leaks...it's the last thing, right?




Doesn't appear to be. What would that indicate?

Pinging would be pre-ignition, knocking would be run-on, both would be caused by ignition problems.(timing or poor fuel)

It would seem that with the MSD it is fireing hot, meaning that spark is jumping from the rotor before and after than it should be. I'm not familiar with MSD, but I've read that it fires on the exhaust stroke as well. Maybe yours is fireing at will. Or since you don't track it anymore, carbon has built up in mass quantities on your cylinder head and there is continuous combustion going on like the coal fire in Pa. ; )