What kind of plugs do you guys running E85 use? I was running one step colder plugs on my 92 octane tune but I recently switched to E85 and I'm getting crazy, scary misfire. Should I change back to stock or go warmer? I did a quick search and didn't find anything really. No definite answer.

 

What gap are you running?

 

Well e85 does a great job of cleaning parts so i wouldn't worry about typical carbon build up. Regap the plugs tighter if its high boost and try again

 

Currently I am running BPR7ES's gapped to 0.024", the bottom of the factory spec. Coincidentally, yesterday out on lunch I was getting blow-out with this set-up. I gapped some BPR8ES's last night to 0.024" to try out this weekend. I am running 27-28.5psi, FWIW..

 

I am running 0.028" for the gap on the step colder plugs. Too big?

 

I run one step colder at .024

 

I'm running BPR8ES' gapped down to .022". I'm on 28-29psi currently.

 

Stock heat range and .020 seems to work really well for E85-E98 or meth injected cars.

 

+1

 

I regapped my BPR8ES this morning to .024". It ran fine for about 4 pulls trying to tune the car then started misfiring again. My AFRs were in the 11's right before peak torque (3.8k-4.5k) then went down to 10's. Maybe it's running too lean?

I've been lowering the AFRs all day to see if it would help. No change.
I put in some BPR7ES and will report back for help. Gapped as .24". Will try .020 if it doesn't help.

 

Well, it sounds a lot like it's misfiring...although it may have been running out of fuel and cutting out rapidly.

I'm on...
1000cc PTE
Standard Walbro
Factory FPR

Injectors are scaled to 665. Too high? Fuel trims are in check pretty much.

 

Your gap is too big, stick with 8 heat range and do .020-.022

 

Hey mplspilot, do you get inconsistent pulls (regarding knock)?

Doesn't E85 burn cooler? Doesn't that ultimately mean run stock or warmer plugs?

 

No it's pretty consistent. Usually no knock.

How it burns is not the point here. You will run high boost leading to higher cylinder pressures and higher temps, so you need to run a colder plug. 7 are stock. 8 is a step colder. You also need to reduce gap because it's hard for stock coils to produce a spark with a big gap at such high cylinder pressures. Which most likely leads to what you are experiencing with spark breaking up on WOT.

Bigger gap is better because it provides a bigger spark essentially leading to a better light off and burn and leads to better power production, but you need a COP ignition to be able to run a wider gap. Without it it has to be reduced to 0.019-.022 at something like 28 psi. Results obviously vary from motor to motor.

 

I am running BPR7ES with the same gap as my 8's @ .024" with no misfires anymore. NO problems.