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I had an older SBC that had two flattened cam lobes and the only real sign was a rough idle. It passed emissions testing and ran fine except for at idle. A vacuum waveform test was how I was lead to the cam having flat lobes.
__________________ 1995 Arctic White T/A M6 Advanced Induction bolt-ons and a few bolt-ins Speed Secrets tune www.fquick.com/dugrat
I overreved mine one too many times with the old lt4 springs, it knocked the lifter retainer plate of the #1 cylinder. I drove it for another 20 minutes before the 2 lifters got stuck sideways and started grinding down the lobes. It started screatching pretty awful that's when I shut it off. Didn't destroy the lobes just ground into them enough that the cam wasn't worth fixing.
I will say that you either have a valvetrain issue or your opti is FUKD up. My bros car had went through 3 different optis last year on the dyno, what a fukn waste of time and it sucked badly. Then finally installed another partsladi opti and the problem went away and the car was perfect. Just like yours it would break up at 5k rpm, the 4th one fixed the problem.......OPtimus prime my friend.
It's not lean up top is it? That can cause breaking up and popping if it is that lean.
PDRA TOP SPORTSMAN WORLD CHAMPION -2002 Firebird Top Sportsman - 4.12 at 176mph 1/8 mile. 765ci on 3 stages of nitrous. 2000 Trans Am WS6 - in the works. -1997 Trans Am WS6 M6- 10.80s N/A, 3,650lbs, 500+ mile road trips. Sold 3/2011.
Scan it during a full throttle run. Does it trip a check engine light at high rpm? This sucks man. I thought the valvesprings were surely the issue.
I am going to scan it but I have to get a OBD2 style connectors for data logging... its the dumb year OBD2 connector with OBD1 pcm....Well I took it for a ride today and when it starts missing it throws a check engine light and then it dosent want to idle...turn the car off and then back on and the light is gone and it idles great...
No it never goes lean at all just starts popping and acting crazy but it will still pull to the shift light at 6400....
Here is a dyno and a pic of the motor in case anyone sees anything I am missing...
Unplug your d6 box and try a run, dynaspark says not to run one it there unit..just saying. Oh yea another thing are you dropping volts as this is happen could be a problem as well....I'm just throwing stuff out there