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Persistent knock retard on e85 flex tune

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I’m dealing with some persistent spark knock timing pull on flex tune e-85. Curious if anyone else has had this issue. 93 octane tune it’s quiet as can be no KR. With e-85 I get 8 degrees pulled at 4K and it runs like crap from 4-6K due to the timing being pulled. On 93 it runs like a scalded dog. I’m still in the tuning phase remotely with my tuner and he’s been super helpful we are trying to eliminate things. There is no knock sensor desensitization at all and that’s the way he tunes which makes sense as he wants to keep the motor safe. It is a weird scenario I have tried two tanks of e85 from different stations the file reads the concentration as 80 -85 percent ethanol. I have not tested it manually as a tester is in the mail. We have pulled timing to see if that helps and so far no change. It only knocks on ethanol and not just a little but a lot 8-10 degrees starting at 4K up until around 6K. No weird noises from supercharger , exhaust doesn’t appear to be hitting anywhere. I have tried the following , different tank of fuel, moved exhaust tips, loosened and tightened all exhaust clamps and bolts, verified clearance, bled intercooler pump. I’m showing 80 percent duty cycle on injectors and fuel pressure commanded matches what is delivered. Doesn’t appear to be a fueling issue at the moment but I’m not expert. Mods are as follows

2018 m6 hellcat
2.82 upper
Ported FAS snout w new stock bearings
Afe CAI
100 mm bbk TB
Cat delete pipes
Muffler delete
FIC 1000 injector
Catch can
Blower spacers and heat shield
Dual in tank pumps
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Discussion Starter · #101 ·
Yes it appears some multipliers are off. As far as knock goes part of your problem is how your knock sensors are looking for noise. That's a guess without seeing the tune. That's a pretty big hint on part or most of the problem I assume. But there are other things wrong in this flex tune than just your knock sensors. Hint number 2 jacking up the knock sensors isn't the answer.
I'm running black Friday deals still ;)
I try to help as many people as I can but it is hard for me to assist shops who are selling products they aren't capable of delivering.
My understanding is that the knock sensor part (desensitizing or changing how the hear knock) is non negotiable if I want flex w my tuner based on discussions as it is hugely relied upon for the flex w his tune. If I want to desensitize the impression I get is that I will need to have separate tunes and do it on the e85 one. If when I go back to 93 the knock is gone I will likely go this route unless the problem solution is realized rather quickly because it's been weeks so far and lots of hours trying to problem solve so if that gets me a solution and I can just have a e85 pulley to swap w separate tune then I will just go that route. My impression is that what we are seeing with my car is very abnormal and an outlier as he reports doing hundreds of these.

I also have a trx that I have purchased a flex tune for as well so I am pretty tied up currently with solutions that do not require changing tuners ( I still can't help but feel like something is off w my particular car since it is doing things that are outside the bell curve of prior builds. )

I really appreciate everyone's time and mental energy helping me find solutions here as this forum is a great resource. I come from LS cars so MOPAR tech is new to me
 

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Correct, this is second revision where timing was pulled (trying to figure the knock thing out)which did not change the amount of KR or the onset rpm. The first one had more timing I have the log from it too but it looks the same as except more timing I believe.

Right. I forgot you had mentioned that he pulled timing

agree, something is way off which points me back to mechanical.

If it’s not lean what else could it be? You already sorta ruled fuel out. I wonder what it would do with only e85 out of a can??? If it were me I would try it just to know

*If it were mechanical it would do it on 93 too
 

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Challenger SRT Hellcat
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I’m dealing with some persistent spark knock timing pull on flex tune e-85. Curious if anyone else has had this issue. 93 octane tune it’s quiet as can be no KR. With e-85 I get 8 degrees pulled at 4K and it runs like crap from 4-6K due to the timing being pulled. On 93 it runs like a scalded dog. I’m still in the tuning phase remotely with my tuner and he’s been super helpful we are trying to eliminate things. There is no knock sensor desensitization at all and that’s the way he tunes which makes sense as he wants to keep the motor safe. It is a weird scenario I have tried two tanks of e85 from different stations the file reads the concentration as 80 -85 percent ethanol. I have not tested it manually as a tester is in the mail. We have pulled timing to see if that helps and so far no change. It only knocks on ethanol and not just a little but a lot 8-10 degrees starting at 4K up until around 6K. No weird noises from supercharger , exhaust doesn’t appear to be hitting anywhere. I have tried the following , different tank of fuel, moved exhaust tips, loosened and tightened all exhaust clamps and bolts, verified clearance, bled intercooler pump. I’m showing 80 percent duty cycle on injectors and fuel pressure commanded matches what is delivered. Doesn’t appear to be a fueling issue at the moment but I’m not expert. Mods are as follows

2018 m6 hellcat
2.82 upper
Ported FAS snout w new stock bearings
Afe CAI
100 mm bbk TB
Cat delete pipes
Muffler delete
FIC 1000 injector
Catch can
Blower spacers and heat shield
Dual in tank pumps
Please buy an E-85 test kit and test every tank you pump. Unless you re using V-P E-85 out of a can, test, test, test. Every time you hear “pinging”, you’re risking ring damage..
 

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My understanding is that the knock sensor part (desensitizing or changing how the hear knock) is non negotiable if I want flex w my tuner based on discussions as it is hugely relied upon for the flex w his tune. If I want to desensitize the impression I get is that I will need to have separate tunes and do it on the e85 one. If when I go back to 93 the knock is gone I will likely go this route unless the problem solution is realized rather quickly because it's been weeks so far and lots of hours trying to problem solve so if that gets me a solution and I can just have a e85 pulley to swap w separate tune then I will just go that route. My impression is that what we are seeing with my car is very abnormal and an outlier as he reports doing hundreds of these.

I also have a trx that I have purchased a flex tune for as well so I am pretty tied up currently with solutions that do not require changing tuners ( I still can't help but feel like something is off w my particular car since it is doing things that are outside the bell curve of prior builds. )

I really appreciate everyone's time and mental energy helping me find solutions here as this forum is a great resource. I come from LS cars so MOPAR tech is new to me
I put 2000 miles on my car and countless tanks of fuel back and forth 93 to Flex, ie hundred of dollars of wasted fuel, time, miles on my car, to end up with a damaged engine because I didn’t want to hurt my tuners feelings. Well they helped out ZERO with rebuilding my engine, did not even discount the demon clone cam I bought from them. And then when I bought the cam and used it, they charged me to retune it for the cam and after five revisions of asking to change the parameters to match what the cam parameters should be They still didn’t do it and that’s when I fired them and moved on. Do yourself a favor and run while you can before your a repeat of me and give @Jonx96 a shot at it and I’m sure you’ll be a smiling man within three or four revisions if that. If he isnt able to do such, I bet you he offers your money back, will your present tuner do that?
 

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I put 2000 miles on my car and countless tanks of fuel back and forth 93 to Flex, ie hundred of dollars of wasted fuel, time, miles on my car, to end up with a damaged engine because I didn’t want to hurt my tuners feelings. Well they helped out ZERO with rebuilding my engine, did not even discount the demon clone cam I bought from them. And then when I bought the cam and used it, they charged me to retune it for the cam and after five revisions of asking to change the parameters to match what the cam parameters should be They still didn’t do it and that’s when I fired them and moved on. Do yourself a favor and run while you can before your a repeat of me and give @Jonx96 a shot at it and I’m sure you’ll be a smiling man within three or four revisions if that. If he isnt able to do such, I bet you he offers your money back, will your present tuner do that?
There’s only been one revision. I would at least give the guy a few more shots, maybe several more…

It’s falling on its face with no timing in it. The only way that is gonna hurt it is if it’s way fat and diluting the oil. You can keep a eye on that. You shoulda heard my buddies new combo first 3 or 4 passes a few weeks ago. Mid 4 second car soooo fat banging and popping like crazy. Timing is what hurts stuff. Lead. Advanced. His isn’t. I understand that does not mean it is not knocking but the pistons are forged lol don’t trip : )
 

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Discussion Starter · #110 ·
I thought for sure I had this figured out today. Doing more looking over noticed my main large vaccum line to the supercharger below the throttle-body was nearly off ( it had backed off to the lip and was barely connected) so I pushed it all the way on and changed my accessory belt to the OEM one from the longer one from the old incognito install. I also noticed my catch can hoses are really easy to disconnect so I figure the seal there is poor. I figured with that pulling air (vaccum line) maybe it was running lean? Anyway, went out and did a pass. Nope, not it. While pulling car back on lift I hit the front airdam on the lift corner damaging it which sent me into orbit. I finally said **** it and walked away too mad to see straight. Here is the screenshot of the log at 4100. I did notice the alcohol percentage calculation showed 57% now with the addition of the 5 gallons of race fuel.

I also drained some oil to look at in the sun for shavings or signs of metal and it looked clean.

Spent another 3 hours on it ( an hour trying to fix the air dam) with zero gain.

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No if those are leaking it throws a code quick style

Why haven’t you gone into the pid properties and changed it for the retard so it’s on the screen as speedy suggested?

What does your tuner say about all this 2:45 on a Wednesday?

*good to hear… I hate those splitters : )
 

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Dumb question but are ya sure it isn’t lighting off on compression alone instead of spark? When I’m forced to run less than 93 octane, my Cat rattles from pre-detonation something fierce when I goose the throttle. Telling it to spark sooner to beat the compression ain’t an option either…. LOL

Eh?
 

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Discussion Starter · #117 ·
No if those are leaking it throws a code quick style

Why haven’t you gone into the pid properties and changed it for the retard so it’s on the screen as speedy suggested?

What does your tuner say about all this 2:45 on a Wednesday?

*good to hear… I hate those splitters : )
Did not email tuner, next move is back to 93. He is closed the next four days or so for thanksgiving. If something had changed or I had fixed the knock I would have emailed him. Sorry, here is the screenshot with timing advance and retard on there.


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