Allright, here's the story. Car runs fine, but I decide on some new spark plugs wires since one touched a header and a new coil. I buy the Thunder Racing OTVC set, Taylor Spira-Pro's 8mm, and a new MSD blaster coil. After instal car runs fine. So about a week later I buy some new NGK TR55's and instal them along with a new tune I got from a member here. Plugs and tune go on at the same time. Car runs fine up until I make a pass. The car now has some high RPM miss, intermiten. Also, if your in 5th or 6th gear and at low RPM's, 1,400-1,500 RPM's, and give it gas, the car shakes violently. So, I start troubleshooting with swapping the tune and coil out, no change in the car performance after this. So I switch to NGK TR6's, gapped at .055, still, no change. Still troubleshooting, I notice the plug wires are arcing along the valve covers, so I buy a set of MSD wires and instal, and STILL NO CHANGE!!

Now, here is my next plan of action, you tell me if you agree or not. While the plug wires were arcing on the valve covers and anything else metal around them, the plugs got "burnt." The "strap" at the end of the spark plug is discolored black. I was thinking of buying another set of NGK TR6's and seeing if that makes a difference. If that doesn't work, the only other thing I can think of is the Optispark is going bad, 60,000 miles on a GM Optispark. This high RPM miss, once intermiten, has now turned into a solid continual miss at high RPM's. Do you think this sounds like the Optispark or plugs?

I know it was a long story, but thanks for hanging in there.

 

i have always known plugs to be around 2000RPM or so, not high RPM. Do you have anyway of running a datalog?

 

I like the Delco plugs myself, gap whatever at .050", anything more and that spark will try to jump places it does not belong.

The opti cap could be bleeding spark
The opti rotor button screw could be backing out causing it to wobble
I think the problem is in your opti, I have seen it too many times. I hate taylor wires and much prefer the MSD wires myself.

 

Yes sir, still got a few trials left on my DataMaster. Want a log of it?

 

wrd1972, you ain't joking about Taylor wires. I was told by someone at Thunder that they get a few calls about them doing this every once in a while. Hmmm, Taylor or MSD?

I guess I can try taking the Optispark apart and seeing if the screw is loose. If not, I guess it's a new Optispark for me.

 

Does it run fine in open loop?(cold) I have the adzact same symptoms and I replaced the opti and no cure. when it was off I checked out the cap and rotor and they looked fine. My car has a heavy missfire above 4k in closed loop and low rpm shake in high gear. still looking for solution.

 

Mine is in closed or open loop, doesn't matter.

 

are you sure you didnt crack one of the plugs.

 

Are you talking about cracking the ceramic part of the plug? Like dropping it and cracking it that way?