90zcrex

iTrader: (11)

First off, Car is a IX that I've self built/tuned on 93 at 24psi and everything ran fantastic.
So finally made the switch over to E85 yesterday and I'm getting a weird bucking/bad misfire only at WOT.
At cruise and part throttle she runs smooth as can be.
My AFR's (gasoline calibrated) are around:
14.5 cruising
13-13.5 spoolup
12.5 ish under boost

The timing map and Boost were left unchanged, All I did was use a lower injector scaling until I got close to the aforementioned AFR's and roughly tuned the map from there.
It feels like bad ignition break up, It's just weird that I didn't have any problems on 93.
I did lower plug gap when I cranked the boost on 93 and beilieve they are set to .020.

Any help would really be appreciated, I can't wait to feel the E85 addiction that everyone talks about

boosted91t

iTrader: (65)

Do you have any logs or maps?

Plug gap seems about right, how new are the plugs? Your using iridium's right If the boost remains the same you can write off spark blowout I guess.

90zcrex

iTrader: (11)

Here is one log. I think here I richened up the afr a bit to see if it would help but didn't.

Svendiesel

iTrader: (25)

If you're not currently doing so, be sure to use a stock (heat range) spark plug, lots of issues with misfires on colder step plugs.

The plugs youll want to use from Mitsu are the ILFR7H. Youll likely find them way cheaper online than at a Mitsu dealer. I think theyre like 22 bucks a plug from Mitsu.

JohnBradley

iTrader: (30)

0.020" gap with a feeler gauge or one of those half dollar looking POS things?

90zcrex

iTrader: (11)

They are the stock plugs, I set them with a feeler gauge. That was probably 2-3 months ago tho, the plugs looked good then but I will pull them out and check them tonight.
Just seems weird how there were no problems with 93 but it breaks up badly with e85.

Dynotech Tuning

iTrader: (12)

We generally run DENSO IKH-24 plugs (1 step colder) with no misfire issues. So far I have run these plugs to nearly 900whp with no misfires at idle, cruise or WOT :shrug: I believe they are only like $12 per plug. I generally recommend changing them every 15k miles.

-Jamie

Svendiesel

iTrader: (25)

Interesting, I recall seeing around here and elsewhere misfire issues with 1 and 2 step colder. Could have been related to maybe too large of a gap, who knows lol

mrfred

iTrader: (50)

my experience is that i get misfire on e85 only when north of 12.5:1. if misfiring at 11.7:1, then if not a spark issue then maybe a partly clogged injector. plugs look ok?

90zcrex

iTrader: (11)

Pulled the plugs last night and #1 plug the electrode was worn down pretty good with a gap of about .030, I've got some plugs ordered to throw in it today. We'll see if that clears it up.

merlin.oz

log line 353 - AFR jumps to 12.9 would indicate a spark blow-out to me.

It is peak torque point too.

90zcrex

iTrader: (11)

Plugs were definitly the problem. Got new ones in it, gapped to .020 and she runs awesome. Started some initial tuning on it, got Afrs decent and turned up the boost. I love E85 already!

PrimerSdime

iTrader: (14)

You'll never want to switch back now.

merlin.oz

Is that .020" on the stock coils?
If so then COP will help the cause and should allow you to open the gaps out to .030"

krys88

I have misfire on my evo 8 on e85 above 35 psi. When I change plugs they will be good with no misfire for around 100 miles and misfire coming back. I tried everything and nothing seems to work to get rid of misfire. I had this car on c16 fuel for 2 years on 45psi boost and never had misfire but on e85 I have to change plugs every 100 miles. Any help would be greatly appreciated.