.16 spark plug gap, still getting blowout. Bad coils?
 

Hey all, I just recently got my 8 tuned on E85 with a target boost of 27 lbs. Made 432/399 on the dyno.
It ran fine on the way home, drove it today and I'm getting spark blowout at wot towards 6500k rpms. Stock block, tdo5/20g turbo. 272 cams, Ams 3.5 Fmic, short route licp, stock route uicp, stock ignition.
​​​​​It's currently got br8eix plugs in it gapped at.16.
It had bpr7eix plugs in it when it was on 93 and I never had blowout.
Am I using too cold of a plug? It idles/cruises fine and runs fine in lower boost but wide open throttle towards 7k I get lots of misfire in all gears.

Any suggestions?

The 8 plugs are brand new,(installed Thursday night, got tuned for E85 Friday) the 7s had roughly 20k miles on them.

i would use 7's gapped at 20.

are sure its spark blow out tho?
sure not tune?

Pretty sure it's not the tune as it had no issue on the dyno or on the way home, or the day after. Only today as I drove it did it start. The plugs were gapped at 18,i gapped them down to 16 with no change.

Tho, now that I think about it, when I pulled the plugs to rego them, cylinders 1,4 plugs were much darker than 2,3. Perhaps the 1,4 coil pack is weak?

You mean it's got a misfire?
No such thing as "blowout".


AFR will be too rich.

Photos of plugs required.

You've probably done what everyone else does and cocked up the fuel pressure.

How does one cockup the fuel pressure with the stock fpr?
And if there's no such thing as blowout, I should be able to run stock plugs gapped at .032 at my boost levels then? I mean, if afr's are good the cylinder should fire, regardless of cylinder pressure?

You'll see when you post pics of plugs.

:rolleyes:

i would try a warmer plug. when you went to e85 you reduced the necessity for a colder plug, but went colder.

Going to swap over to a Toyota COP setup today and put in bpr7s and see if that fixes it

From what I've read that seems ti be the case. When I picked it I just read through threads on what people were using for E85 and the most common was the br8 so I tried it, didn't work quite right lol
Hopefully going to the bpr7 and the COP fixes it.

Spark flame does not blowout. What happens is, the spark makes the jump a little too late, due to various reasons such as the wrong plug, a worn plug, a worn/weak coil, too rich of a mixture, too lean of a mixture overheating the plug, or if it jumps on time it is too weak, or both.


At the boost pressure and density of mixture you are running there is no need for an ngk 8 plug. The 7 heat range is more than ok, even if you were on pump gas. The comment about the e85 burning cooler is correct. Thus in your case or any same one, two things happen, there is carbon build up within the spark plug due to a rich e-85 mixture which burns on the coldest side of things thus not allowing the spark plug to reach optimum functioning temperature and remain there and or you also have a weak coil which enhances the carbon build up and it does not charge the plug properly for it to fire as it should.



Get a new set of coils before you change the plugs, see how much it improves the problem, do not go to the 7 heat range plugs, keep the 8s, otherwise if problems still is at some degree, change the plugs also to 7s and you should be ok if there is no other electrical/ecu malfunction.






Marios

I plan on going to a COP setup today, the 1 and 4 cylinders are the plugs that were darker nearly fouled looking to me which seems it'd be the coil for those cylinders. I'll try the new ignition setup with the 8s and see how it does as they're brand new iridium plugs.

The colour of the plug has nothing to do with the spark, it's the AFR.

Changing to COP will make it run worse.