Knock on e85 not a problem?

[MrSlay]

Originally Posted by gdrider77

So i tried reflashing to an older tune. This was the original e-85 tune my tuner gave me. This has always ran the best. So thought i would give it a try again and see how it runs. Well runs great. CC still does not work, but thats another issue.

Lowered boost to about 10psi, will be pulling out the mbc and just running wastegate for some tests soon.

Knock is only occasional and its always a -1 or -2. Thats the most i ever get with this tune. Under all conditions. Also, on my AFR wideband. Pretty much around 11-10.6 on most full boost. A couple times dropped to a 9.6, but out of alot of pulls and time (60min) it was only around 10times?

Probably just run this tune for now till i can get it sorted out.

Can pull some logs and post those later.

Thoughts?

Is your Wideband calibrated for Pump or e85? If e85, the AFRs are pretty safe as you should be shooting for somewhere in the 9.8-10.4 range.

Though your car is running better with the old tune, I would still get the car properly tuned to where your not getting any Knock Correction under boost. May take some time, but it would be beneficial to take it easy until you get everything done the correct way.

[gdrider77]

Originally Posted by MrSlay

Is your Wideband calibrated for Pump or e85? If e85, the AFRs are pretty safe as you should be shooting for somewhere in the 9.8-10.4 range.

Though your car is running better with the old tune, I would still get the car properly tuned to where your not getting any Knock Correction under boost. May take some time, but it would be beneficial to take it easy until you get everything done the correct way.

I am running an Aem fail safe. Was not aware it could be calibrated for e-85. So I would say no.

Still trying to figure out the tuning situation. For now have the car parked and won't be driving till I can get it figured out. Might give my tuner one more shot since he offered to start over from scratch. But won't be for at least a month till he can look at it.

His customer service is lacking in my opinion. While he offered to fix it for free, he should offer to get to it ASAP, and not put new customers in front of me. The fact that he already took my money and is not quick to fix issues is disheartening.

Much like another recent tuner on the forums. Which is what is scaring me from remote tuning as well.

[MrSlay]

Originally Posted by gdrider77

I am running an Aem fail safe. Was not aware it could be calibrated for e-85. So I would say no.

Still trying to figure out the tuning situation. For now have the car parked and won't be driving till I can get it figured out. Might give my tuner one more shot since he offered to start over from scratch. But won't be for at least a month till he can look at it.

His customer service is lacking in my opinion. While he offered to fix it for free, he should offer to get to it ASAP, and not put new customers in front of me. The fact that he already took my money and is not quick to fix issues is disheartening.

Much like another recent tuner on the forums. Which is what is scaring me from remote tuning as well.

Hope it works out for you. If i were in your situation and it came down to worse case, I would approach one of the top tuners local to you and just give him your car for a couple of weeks. Tell him to take is time, learn the platform, and get it right. That way you'll get a solid tune by someone local to you, and could possibly get the car tuned for free as your providing him a vehicle and tuning solution to break into a new and thriving market.

[gdrider77]

Originally Posted by MrSlay

Hope it works out for you. If i were in your situation and it came down to worse case, I would approach one of the top tuners local to you and just give him your car for a couple of weeks. Tell him to take is time, learn the platform, and get it right. That way you'll get a solid tune by someone local to you, and could possibly get the car tuned for free as your providing him a vehicle and tuning solution to break into a new and thriving market.

hahah...yeah. That was basically what i did."""Tell him to take is time, learn the platform, and get it right. """ My tuner is "local" and considered a very good tuner here. I know people that have drove states over to him. I left my car with him for a little over 3 weeks, and paid him. Told him to take his time, and that he could keep the car as long as he needed to get it done right. I was in no rush.

Problem is, i think the car is a new platform, he is not use to it, and he doesnt really have the desire to learn it. He has told me that he would prefer not to work on these after working on mine, as they are just a difficult car to tune. And take too much time. He can tune 2-3 wrxs in the same time as one frs/brz.

I actually have to stay with him the whole time he tunes the car, otherwise he wont work on it. Last time i was there for 12 hours or so, and he got frustrated a few hours in, and even said that if i wasnt standing right there and waiting, that he would park the car and not work on it anymore for the day.

So im with you, as i thought originally that leaving the car would help, but doesnt seem to be working. While he had it for like 3 weeks, i dont think he really even worked on it during that time. Because once i told him i was coming up to check the car out, he told me that he was working on it that day and it would be ready the next day...I think he just jumped on it, knowing i was coming up the next day.

ugh...just talking about this its sooo frustrating. I have one other tuner a couple hours away. He has not done a turbo tune on this yet, but he at least owns one. Plus he is going to be developing a turbo kit this winter for his....I might try talking to him and se if he wants to take on the project..

If not, then i will be driving somewhere to get the car to one of the tuners that are established.

[Sportsguy83]

Originally Posted by MrSlay

Is your Wideband calibrated for Pump or e85? If e85, the AFRs are pretty safe as you should be shooting for somewhere in the 9.8-10.4 range.

Though your car is running better with the old tune, I would still get the car properly tuned to where your not getting any Knock Correction under boost. May take some time, but it would be beneficial to take it easy until you get everything done the correct way.

AFR gauges (like AEM failsafe), use lambda =1= stoich, so even though Stoich AFR for E85 is 9.76 and Stoich AFR for Pumpgas is 14.7, the gauge will still display both as 14.7.

I have the same AEM failsafe and optimal AFR's on the gauge are the same as pumpgas 93 because it equates stoich to lambda 1 and skews the values even though for E85 its really in the 6-8 AFR range.

[gdrider77]

Originally Posted by Sportsguy83

AFR gauges (like AEM failsafe), use lambda =1= stoich, so even though Stoich AFR for E85 is 9.76 and Stoich AFR for Pumpgas is 14.7, the gauge will still display both as 14.7.

I have the same AEM failsafe and optimal AFR's on the gauge are the same as pumpgas 93 because it equates stoich to lambda 1 and skews the values even though for E85 its really in the 6-8 AFR range.

Would you say that the aem logs are accurate then as well? So if it says I'm at 9.6, then that is being adjusted for e85 also. Which in turn, means that's a concern?

[Sportsguy83]

Originally Posted by gdrider77

Would you say that the aem logs are accurate then as well? So if it says I'm at 9.6, then that is being adjusted for e85 also. Which in turn, means that's a concern?

Yes, it is a concern. To give you an idea, I was getting cylinder Misfire CEL (P0301) BECAUSE I was dipping into ~9.5 AFR. Now my map usually dips only to 11 and occasionally to 10.4 and no more misfire CEL. You should be seeing anything from 10.5-12.5. Any AFR above or below can cause all sorts of chaos like misfires and knock.

See below posts for a detailed explanation of AFR, E85 and regular gas.

Originally Posted by mad_sb

OK, so the difficult thing for people to wrap their head around is this: air fuel sensor measure lambda, which then gets converted to the AFR scale of your choice. The stoich point for gasoline and Ethanol are very different but because the air fuel sensor will report each fuels stoich point as lambda 1.0 which gets converted to gasoline afr in most cases your stoich point is still 14.7:1 on the gasoline scale.

So,
E85's Lean Best Power is Lambda 0.8673 or (14.7*0.8673) 12.75:1 on the gas scale
E85's Rich Best Power is Lambda 0.7143 or (14.7*.07143) 10.5:1 on the gas scale


E85 will tend to knock on the rich side more so than the lean side. I would think 11.5 would be a good place to start with boosted applications and move a little up or down depending on the tune and what the car needs to be happy.

There is no exact answer though because it will depend on ignition timing, boost level, turbo efficiency, etc etc etc. Over all I would think a little bit leaner than pump gas on a gasoline calibrated wideband.

Originally Posted by Sportsguy83

Ok let me get this straight. The O2 sensor reads lambda, which at 1.0, is measuring the stoich point for whatever gas you are using. It then considers 14.7 AFR as lambda 1.0 obviously again regardless of fuel.

Then using your conversion we get the max lean max rich figures converted to AFR for E85.

What are these lambda values for 93 pumpgas? THANKS for the help!!


Edit: I think I'm starting to understand this a bit more. So the REAL stoich point for E85 is not 14.7 AFR but 9.765 AFR. So if I were to want to know the real AFR for E85 when my gauge is telling me 10.5 right now, I would multiply .7143 lambda* 9.765 (real E85 stoich AFR) and that would give me 6.97 AFR. That is the REAL AFR, but since our gauges are calibrated for pumpgas, it will show .7143 lambda *14.7AFR = 10.5 AFR