oneBADDz

iTrader: (26)

Bone stock 99 WS6. Car threw P0307 after a bad shift and over-rev. Prior to knowing it had been overrevved here's what was done

Changed the plug - it was white like the car is lean
Changed the wire -still not fixed
Swapped the coil to another cylinder - code stayed on #7

Found out the car had fallen victim the the infamous 2-3-2 shift at the track and the misfire showed up right after the run.

Pulled out the pushrods, they aren't bent. Swapped them for two other pushrods I had available anyways. Not fixed.

Decided to check out the injectors and this is where it gets wierd. Engine running, being held at 2000 rpm, I pulled the plug off of the #1 injector to see how much it stumbled, put it back on and pulled the plug off of the #7 injector and nothing happened, no stumble like it did with the one that was known to be functioning. So, swapped the two injectors and the code still stayed on #7. Rechecked the stumble by pulling plugs off of injectors and the same thing happened even after swapping the injectors, #7 was still the problem.

What's next?

keliente

iTrader: (22)

Could the lifter(s)/valves on #7 perhaps have thrown in the towel to the dreaded misshift? Over-rev/bad shift just screams valvetrain issue, especially since it came on right after.

oneBADDz

iTrader: (26)

That's why I jumped right to the pushrods once I found out what had happened. From time to time you can hear a little tap, but not loud and not but maybe 5% of the time. What about the injector thing though? Why does unplugging the #7 injector not affect idle or running quality, and after we switched injectors from another cylinder it remained the same. This is a problem that have no experience or knowledge on diagnosing and I'm just lost. What more can I do to check stuff out? I told him to get a compression/leakdown test since I don't have the stuff for it. Worries of a bent valve has crossed my mind, but I don't know what steps to take next.

Da Swami

iTrader: (6)

If the intake valve/lifter on #7 was messed up the injector wouldn't matter, functioning or not.

It would basically be spraying into a wall.

oneBADDz

iTrader: (26)

So are we looking at a comp/leakdown test and then using the results to decide if we're pulling the head on that side? If it passes we'll look into something obscure like the cat or O2 sensor?

keliente

iTrader: (22)

I'm not sure a cat or 02 sensor would cause a specific misfire to one cylinder...then tend to screw things up all over or on one bank. I am really thinking that since it's not the pushrods, its got to be a valve or lifter.

oneBADDz

iTrader: (26)

That's why I said obscure, lol. The comp test goes down tomorrow, I'll update when we know something. For once the LS1 pushrods were just a little too strong. . .