Mach 5

I suppose I could have a bad 951Max chipset, but they are designed to allow much more boost than stock. If I can't get the current set up to work, I will probably bring everything back to stock, including chips, cycling valve, and wastegate. However, the set up I have now is used by many other owners, it's not a unique arrangement.

Roger

Mach 5

Well, I'll try setting the FQS back to the default and see if that has any effect. My next step will be to set the boost back to 10 psi and reinstall the stock ECU and KLR chips. I assume I couldn't use the stock KLR chip with the 951Max ECU chip?

Again, I welcome any suggestions, especially from "advanced users" in this area.

Roger

fejjj

You should still be able to use the Stock KLR chip.

Mach 5

Shawn,

You may have been right about the plug gaps being off. I pulled the plugs on Sunday to check them again (just replaced them a few weeks ago), and the gap was much wider than the factory specified 0.028". God knows what I was doing when I installed them. I think a friend stopped over while I was changing them with my son...then came beer & frivolity...well you get the picture.

I set them to 0.026" (a lighter tighter), then reset the FQS to position 0. I tried to explore WOT above 5K as best I could a couple times and it did not hesitate or cut out. Unfortunately, I probably won't know for certain until I hit the track again (Road America over Labor Day). I'll keep my fingers crossed.

Roger

User 41221

It might be a long shot but this sounds like the symptoms you will see with a broken valve spring.

Regards, ...Scott

Mach 5

If it were a valve spring, would still only happen at WOT? I gradually brought the revs up to 6K and drove for a bit (in 2nd), and it didn't exhibit any symptoms.

Thanks.
Roger

User 41221

I would think from a physical standpoint, 5k rpm would be the same as far as the engine was concerned regardless of throttle position, but I can't say with certainy how it would react.

vette951s

I had a similar problem at the track once, turned out the spark plugs I installed (as recommended by Jon Millage no less!) were too cold a heat range.
Good luck! John

Mach 5

John,

Do you recall what plugs were giving you the problems, and then what plug you used to resolve it? I have Bosch WR7DC+ in there now.

Roger

Ski

Does it stutter, have a little sound to it sort of like tongue on roof of your mouth, flutter sound? If so, a spark plug wire could be arcing over to ground, had this happen before. But if its smoking black, get that fixed first.

Mach 5

It was, but only above 5K and at WOT. The plug wires are new, and I checked them for fit. I guess it's always possible that there was a defect in one. It also doesn't normally spew black smoke. I only mentioned this because a couple of the guys following me on the track said occasionally, it blew out a puff of black smoke, like twice during the day. I suspect this may have been a combination of the engine not firing properly above 5K, and the FQS being set to a +3% fuel setting (I should reiterate that there is no CAT as well). This may have left unburnt fuel in the exhaust.

I drove it as hard as possible on the street with the reset plug gaps and reset FQS. No issues. Hopefully this resolved it. I'll fine out for certain in a couple weeks.

Roger

Ski

Good luck, mine were new from Pelican and #3 arced at around 5200, discovered it on the dyno. It was arcing right at the black boot and red wire to the fuel rail.

vette951s

Roger- IIRC they were 2s and I replaced them with some 7s I had at the track. Like you, I was driving myself crazy trying to solve a high rpm miss when I remembered my old motorcycle days when new spark plugs solved most problems!

Good luck! John

Mach 5

For future readers, I thought I'd give some closure to this thread. I ran the car at Road America yesterday. Ran great. No cutting out issues. I think I can confirm that it was excessive plug gaps that were causing the problem.

Thanks to everyone for your suggestions.

Roger