I'm getting a sputtering / backfire at full boost (30 psi). This started happening after about 5 runs down the track. My last run I parked the car and everything was fine. It sat for about an hour. Then on my way home the issue started. Its not throwing any codes. Car is e85 tuned. I already checked the plugs and they look fine. Thoughts?

 

your spark plugs, you need a new set and a new lower gap.
30 psi? I hope you replaced your stock head studs with ARP ones.

 

+1 on plugs

 

it happened to me, and i had to do what this selp is saying^^^

 

+2 what selp said. As long as you are sure your timing is good and you don't have anything too crazy, it is probably just plugs and needing a smaller gap. Try em at .20

 

Head studs were definitely replaced with ARP.

I'm currently running the NGK BPR8ES gapped at 0.020” When I pulled them they didn't look bad, I'll pick up a new set today and see how it goes.

Thanks guys.

 

UPDATE: Put some new bpr8es in and its running perfect. thanks for the responses guys, much appreciated.

The real question is, what made these plugs fail in about a month?

 

I'm having the same problem on Q-16 so I don't think it's fuel related. Do you have an ignition amplifier?

Bump to get some answers!

 

Don't need an amp. Depending on how they are gapped they tend to open pretty quickly.

 

Been having the same problem, going through new plugs about every ~1500 miles on my fp red at 32 psi. What about E85 makes me go through plugs so damn fast?

 

im running e85 as well(35r at 34psi), i dont go through plugs nearly as fast as i do on pump gas, but im running pretty rich on pump gas.

anyway, i was breaking up really bad through fourth gear pulls on ethanol about a month ago, i had checked the plugs and they didnt seem bad, but thats only because they dont accumulate soot and carbon which is what i was used to looking for.

changed the plugs and i was fine. im using a cop set up so i dont need to gap the plugs down, but plugs do need changed rather frequently.