So here are the basics.
2.0 9000rpm rev limit
37r @ 25psi
AEM EMS
Cali E85

So for the last week or so I have been fighting this knock on e85. I have tried everything under the son to get this knock.

I have gone from 12.0 afrs - 13.0afr's
I have gone from BRP7ES @.020 - BR8ES @ .024-.018
I have run lots of timing and very little timing. I am kinda at my witts end here. Any advice will be helpful.

Also if you want the full log file I can email it to you.

As you can see from the log below, the car will start to knock pretty bad at 8200rpm and 12.50 AFR and 14.3* of timing. It starts to missfire and then by about 8500rpm the will buck and just start to loose tons of power.

Current conditions during this run.
BR8ES @ .018
25psi
3* @ peek boost
16* @ peek rpm

 

Since its happening at high rpm only it has to be ignition related. I never had a issue like this so i cant honestly give you any good advice, because i do not know how these motors act past 8500+. Maybe a coils going out or something?

If you want to take it to a good tuner in cali to look at go to GST motorsports. Bryan is very good with E85.

 

Yes I would like to take it to GST however they are about 500miles form where I live. So that will not happen.

As far as the ignition breakup. I have tried a varity of things to clear it up. I am going to remove my AEM TwinFire and see if I can get a good clean pull to redline.

 

I know timing is not crazy high or anything but you could try backing the timing down to see if that helps.

 

that will make it worse oldevodude...

 

probably the twinfire or double check your battery is 100%.

 

Do you have the same knock issues on 91 octane and/or 100 octane or another race gas?

 

I agree with ignition suggestion. How did the plugs look after you pulled them? I would swap out the twin fire for a different COP or at least try one if you know someone in the area who has an Evo that will let you borrow theirs.

 

Plugs always look good.

Last nigh I did a few tests.

1. Checked for anything loose in the engine compartement/attached to the motor that migh have been loose. If loose I tightend up.
2. Put new Dieletric Grease on the COP between the Coil Conductor Spring and Plug
3. I increased the timing up top from 16* to 20*
4. No change to AFR.

Knock was exactly the same. So this tells me it is not a timing issue.



Second Run
1. Added fuel from 7300rpm to 9000rpm
2. Set Target AFR's to 12.3
3 Timing still at 1.2* peek boost 21* peek rpm

Car made a much cleaner pull to redline. There was still knock up in the top but no where near as bad as before.

 

I did not have this issue on Q16 or 91oct. This is 100% specific to E85. This weekend if I still do not have this 100% figured out, I am going to drain all of the E85 and fillup with 91 and verify that this is an E85 problem.

Just before I switched to E85, I just finished hitting the race track on Q16. I drained the last few gallons of Q16 out of the car and filled up with E85. When I first stated to tune on E85 I did not get noise like this. My guess is that there might have still been 1 gallon of Q16 in the car helping the E to burn and now that I am at my 3rd 5 gallon fill of E85 I think that is why I am starting to see this.

I am going to open up the gap on my plugs tonight and see where that takes me. I am trying to do one thing at a time so that I can figure this out. I can normally only get about 2 runs in per night. I dont want to **** over local law enforcement too much.

THe main goal of me understanding this is so that I can hit the dyno early next month. I will have some 2150cc injectors on the way, and I want to make sure that I can really get the power I am looking for out of this fuel before I invest in the huge injectors and the dyno time to tune my car.

 

Have you tried going richer then 12:1 AFR?

 

Is your MAF secured or in close vicinity of anything? It may be tapping against something as your motor revs up. Tapping on the MAF can cause knock.

 

He is using AEM.... aka speed density, so NO MAF!

 

what is your base ignition timing setting?

 

Thats just the noise profile of the turbo. When it gets full song it just starts getting nutty. Tell the knock retard to ignore anything over 2v above 8200. It is pulling timing and slowing down because the voltage is set to low.

The main drawback of an AEM is the really simplistic knock control. Voltage reflects amplitude of noise at a given frequency. Too many things in the engine bay can generate a 6500hz signal at high amplitude.

Here is a log from my last dyno-