E85 afr

[dbcruzr]

Hey guys,
I just converted to E85 yesterday and I'm a little bit confused. I have 60# injectors and set the IFR to 42 across the board. I know I'm supposed to do some maf tuning for my fuel trims but I'm confused as to what my wideband should be reading. Its an AEM calibrated for gas. Does it read E85 like it does gas? as in 14.7 on my wideband for stoich is okay? I understand E85 stoich is around 9.6 or 9.8 but why does the wideband read regular gas values? Am i missing something i need to change?

 

[Anthony Smith]

yes, Lambda 1 on your wideband which is calibrated for gasoline will read 14.7 when your actual E85 AFR is at 9.76. On a lot of controllers you can go in and change the calibration to read E85 specific but if you already use and understand your wideband numbers for gasoline theres no reason to change it.

 

[dbcruzr]

Awesome thank you. I just wanted to make sure I didnt do something wrong. My next question is at wot my afr is around 10-10.5. For PE, my base AFR vs ECT is 11.7 for all temps above 68.0. will a maf tune help lean it out? or what else can i do? Its currently at 18* with no knock on a 3.4 pulley and 1.9 rockers.
Edit: Im using HPtuners

 

[Anthony Smith]

I dont use HPT but there are some other modifiers and factors that work their way into the mix before you get your final AFR. Get your ltft dialed in first so you have a consistent base AFR then if its still rich, start trimming it back which ever way you choose. "some people" would scream from the roof tops that you will never have to change your MAF table. but that is one effective way of doing it

 

[Fivefingerdeathpunch]

I've only really ever adjust the MAF below 7000 hz.

In the PE table, there is a add vs time table, you can adjust that so it doesnt add more fuel over time.

 

[91parkave]

E85 Afr is actually 9.85 secondly its been proven now you can change your master stoich value and modify your pe. And be done with it.

 

[dbcruzr]

I've only really ever adjust the MAF below 7000 hz.

In the PE table, there is a add vs time table, you can adjust that so it doesnt add more fuel over time.

7000hz and below? In the starting hptuners sticky he says 7000hz and up?

E85 Afr is actually 9.85 secondly its been proven now you can change your master stoich value and modify your pe. And be done with it.

What will changing the master stoich do for me?

 

[97AutoXVette]

What will changing the master stoich do for me?

The ECU uses the Master Stoich value for all fuel reference tables I believe (PE tables may be excluded). Setting the master stoich to 9.85 will be your new ECU target for AFRs at all times when you're not in PE mode. If you change that stoich value, make sure you also check and recheck your PE tables to make sure you don't have too large of adders vs. throttle position. This could make your new target AFRs actually HIGHER than stoich. once you get into PE mode. Let us know if you need clarification before/after you change your PE tables. I have played with these enough to know them like the back of my hand

 

[97AutoXVette]

set your base PE AFR to anywhere between 7 and 7.5ish to start. then I would make your adder vs. throttle position something around 1 to 1.5 for throttle positions up through 40% or so (then drop off the adder to 0 for all throttle positions higher than that). My PE table kicks in around 28% throttle (when I start building boost). That way, you'll be targeting AFRs around 8.5 to 9 when you get into PE mode, and once you get to 50% throttle or more, you can go to your base PE targets (7 to 7.5). If you aren't running too much boost or seeing knock, feel free to increase that adder out to a higher throttle position (maybe around 60% or even higher). E85 is more forgiving and your intercooling effects are helpful in this case so you can likely stay "less rich" further out into your throttle position and still be safe.

 

[Shmoke]

Is there a generally accepted "E85 How to:" that we can follow? How does the steel gas tank and the 98'-02' fuel system stand up to the stuff?

 

[97AutoXVette]

Is there a generally accepted "E85 How to:" that we can follow? How does the steel gas tank and the 98'-02' fuel system stand up to the stuff?

There are several threads on this forum which include most of the info you'd need to switch over to E85. I haven't had issues with my gas tank yet, but it is likely a good idea to change out the filter before you switch over, and then monitor it on occasion just to make sure it doesn't get clogged up. I have been running E85 for around 2 months now and haven't had issues yet (that I know of). haven't changed the fuel filter since changing it right before the "switch over" either.

 

[Shmoke]

How did you do it? Give us the short and sweet version. What tables need attention?

I feel like I could just open up the injector scale by 30% and be in the ballpark. I just cannot picture all of the consequences that will likely come from other tables.

How do you like it? Did you drop a pulley or raise timing? Have you been to the dyno?

I have a 1999 also (The Best year IMHO). With a 2007 cammed L32, a 2005 transmission, a 2003 PCM and the original 1999 fuel system and engine electrical. And she sets no codes and purrs like a kitty cat.

 

[97AutoXVette]

Ha, where to begin!

http://www.grandprixforums.net/thre...re-s-what-I-learned!?highlight=here's+learned

That is a short thread I put together on changing over and what can be addressed in the tune. A correction to the timing tables section: I would stick with stock timing and not add ignition advance personally. That has worked best for me and others have attested to the same thing.

How do you like it?

I LOVE IT!!!!!

Did you drop a pulley or raise timing?

I got rid of a TON of KR (like 9* of KR... no joke) dropped a few pulley sizes as well

Have you been to the dyno?

Not yet but after I drop pulleys again within the next couple weeks, I am anxious to find out how much power it's putting down. Almost anyone who changes over seems to love it. shoot me a PM and I can help you with your specific tune. Should be able to set up a tune for you that will work well.

~Andrew