hi Everyone,


I'm stumped and not sure what else to be looking for. To keep it short, 91 map runs perfectly fine without any misfire issues. When I switch to E85, I get a breakup/misfire issue on full throttle but I am not getting any CEL's going off.


The plugs are the correct ones for the Evo IX and gapped correctly to .24. I was originally running Spoolin Up COP and thought once of the coils started to go so I swapped back to the stock coils and same issue. I'm also detecting a random low RPM misfire probably around (1500-2500) but doesn't happen to often but I can tell when it misses. I recently did a boost leak test and I have 0 leaks.


I did my research but couldn't find a definitive answer, some say crank angle sensor, cam position sensors, resistor pack etc. One thing to consider is that my IX is getting old, she's about 120k miles but I have never had any issues whatsoever.


Any help would be greatly appreciated, I wanted to get feedback before replacing stuff because the sensors alone and resistor pack are close to $400

 

go to a .020 gap

i'm assuming you have two different maps, one for 91 and one for e85, based on your post?

 

thanks, will try gapping down further. Yes correct, I have two maps.

 

I'm just going to state the obvious here. Your 91 map runs fine buy your E85 map doesn't? Seems like you should have that e85 map looked at. Who tuned the car?

 

Close the gap, test the E85, test the coils from the Spoolinup kit.
The COP kit should run better than the stock ignition, so try to test the Spoolinup Kit and get it back on the car.

 

Not necessarily the issue. E85 puts a much larger demand on the ignition system.

OP, replace the plugs if you haven't recently and gap them down to .020". Also, make sure you got decent E85, and not something more in the E50-60 range. You can google how to make a tester, or buy them off Amazon.

 

Good advice here.

For my Evo 9 on E85, I use OEM replacements NGK ILFR7H gapped to .020"

 

thanks everyone, I gapped them to as small as .018 and misfire was still taking place. The plugs are brand new (correct ones for IX ILFR7H) and the E85 is good. The coils are good as well, tested them with stock working unit and misfires still occur with stock coils. To add some clarification, when I said it was running fine on 91, this was at a track day. When I was headed home, I refilled on E85 and noticed the misfiring issue at WOT.


I switched back to 91 and it was still misfiring. As I was getting low on 91, I decided to dump some Redline fuel injector cleaner to see if that made a difference. Still no luck, as I was about to run out of fuel and decided to go back to E85. Surprisingly, most of the misfiring went away....there is just a slight miss but it pulls normal again.


Here is where it gets weird, the next morning I had a hard time starting the car (not cold enough for E85 hard starts) but it finally fired up. It seemed it was running on 3 cylinders lol (sounded like a Subaru). After a few minutes of idling, it went away and was back to normal...no misfires at WOT. So this morning, I started it up again and same thing except it went away much faster this time.


I'm starting to think I may have a clogged injector, I've been running E85 for the past 4 years non stop, hardly running 91. Prior to all this happening, I ran a few tanks of 91 for a track day then this started happening after (car ran 100% fine without any issues at the track). Here is my thinking, the 91 I ran through cleaned up E85 gunk over the past few years, the fuel injector cleaner also helped clean. Gunk may be stuck at the injectors causing the hard starts and running on 3 cylinders sound in the morning. Does this sound plausible?


Either way I'm going to take the injectors out this weekend and have a look at them to see if they need cleaning.

 

Can anyone else chime in? I'm having serious misfires at wot too. It sounds like the car is rapidly farting. I found lots of gunk on the tips of my injectors. I only have 1 map which is e85 n Ive been on e85 for a year straight. Gapped to 20 also. Probably gonna clean my tips today n wipe them down good. I'll come back update.

 

I have misfire on my evo 8 on e85 above 35 psi boost. 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.

 

if the plugs are good... and gapped around .02...

then is it going lean?
sounds like tune.

 

When plugs are good and gapped to .018-.019 runs perfectly fine wih afr 11.8-12.0 on boost and timing similar to my c16 map which is around 6 degree at 6000rpms and 13 at 8500. But when have misfire afr jumping to 12.4 sometimes 12.6 on boost but only for split second when have misfire and going back to normal when misfire is gone. I tried br8es than br9es . I changed my cop coils to brand new denso coils. Still same results. It is running with no misfire for 100-150 miles than I need to change them.