Hey all,

While road racing, I find I lose power at WOT (100% throttle) and above 5500 RPM with a slight miss. However, if I let off on the gas just a bit (but still in PE mode), then the car seems to gain the power back and lose the slight miss. Further, this issue seems to be a hot issue. Meaning it happens when the car sees a coolant temp above 210 F.

Not sure what could be causing this. Give me some leads.

Thanks,
Ben

 

dying opti maybe? Datalog it and see whats going on.

 

Have you checked the fuel pressure at WOT/max RPM?

Have you considered the possibility of valve float?

 

No codes. Opti has about 250 miles on it. Granted, high rpm miles. I want to rule everything else out before I go this route again.

BTW, everything is new from battery to plugs: battery, PCM, ICM, coil, plug wires, plugs. OK, plugs have 1K miles on them. Alternator was just rebuilt and have not had a chance to test this item. They said the brushes were worn.

 

Glad to have your opinions and suggestions on directions to go.

I have not checked pressure because my datalogs show smooth O2 all the way to limit. I know this is not a perfect indicator but I would think there would at least be a 30-50 mV drop at the end if pressure was bad. Thankfully, I CAN check the pressure and so may if this continues. Good idea.

I have not considered valve float because when the car is lower than 200 F and I rev to limit, the car is glass-smooth. Would valve float come into play when I just let off the gas and keep the same RPM but now the car smooths out?

Thanks,
Ben

 

could be your coil breaking down when it gets hot. Try adding some space between it and your cylinder head.

 

That has been done also. Thanks for the idea.

Keep throwing me ideas to try.

 

Well brand new plug wires with heat shields and one is burnt! I think I found my issue.

A note: Summit Racing's plugs did not hold up to heat at all. With a shield, they did not last as long as my others that were unshielded. Rubber became soft.