Never got a response here but figured i would post a follow up in case someone searches.
I changed my spark plugs on Saturday and also pulled my 550cc injectors to be flow tested and cleaned. I was running the NGK PFR6J11 Iridium plugs. These only had a few thousand miles on them. However, even after putting those plugs in with new wires, I was still getting blowout. Even though i told the shop that installed them to gap to 0.028'', i found that 4 were 0.031'' and 2 here 0.035''. That actually made me feel a little better, because i am pretty confident now that the 2 with the larger gap were the source of my spark blowout - it didnt seem bad enough to be all 6. I also measured the resistance of all the spark plug wires and they were well within spec.
I ended up going with NGK 4091 R5671A-7 after reading some threads and the notes here (https://www.rvengeperformance.com/20...commendations/
). I gapped them down to 0.026’’ and will see how that goes. I am feeling pretty confident now after finding 2 plugs with a large gap, switching to copper non-resistor, and lowering the gap.
I did find quite a bit of deposits on 4 of the 6 plugs (not correlated with the two that had the larger gap, I checked). Key picture is below and more full size are at the link here (https://imgur.com/a/OCUDSHs
). I think perhaps the white specs are from a E-85 fuel stabilizer I was adding a little bit of since I started running 50/50 E-85 and pump 91. I also know my VSS are pretty shot because I get smoke on decal, so that could be contributing to some buildup as well. Picture shows spark plugs in order – front of engine on the right side.
Any thoughts on these? Nothing looks terrible, but interesting that 2 look much cleaner than the rest.
Will post another update after i get the fuel injectors back, put everything back together, and try running 15psi again.