Sc14 to buick and e85

[antus]

If you want to gather that kind of data research what sort of lambda you want for stoich and power etc. That is a number where exactly 1 is stoich and its irrelevant of fuel type.Then you can find a multiplier to convert that to the AFR for your given type of fuel. If you go this way you can convert any documentation to the ratios of fuel you need. Because lambda is not limited to types of fuel it actually would make more sense to use this all the time (and some people do) but air/fuel ratios are in a lot of peoples heads (and in a lot of tuning software) so thats what people tend to use.

You can use this:
http://www.wallaceracing.com/air-fuel-lambda.php

EG enter 12.5 pick gasoline and hit calculate. That shows that lambda 0.85 is equivalent, as is 8.3:1 for E85.

[TdracerTd]

I sort of get that. 1 lambda = 14.7 petrol = 9.8 e85 etc. Working from that, would I be right In saying that I could leave the wideband in petrol mode and all of my target afr tables for petrol, and because you need more fuel to get to stoich with e85, just add the fuel required to make it there. At 14.7 it's stoich?

What I'm saying I guess is the voltage from the wideband is the same regardless of the fuel type or have the data is output. So I know I need to put more fuel in to to reach my target, but it doesn't matter if I'm aiming for 14.7 or 9.8.

[Holden202T]

as long as the gauge is outputting lambda....

but that said, all your target AFR tables in that tune i did for you are in E85 so why not just leave it to display E85 and match wideband reading to target ?

[TdracerTd]

Yep, that's what I have done. It's working fine. Just trying to understand where the target Afrs come from. I'm guessing they are from experience? I mean how do you know you need x afr at 3000 rpm and 120kpa?

I get that you need to adjust the fueling tables to make the actual afr match the afr tables, how do you know the number in the afr tables is optimum?

[Holden202T]

Only way to really know for each motor is the dyno! But then you can get max power and richening slightly will probably not change the hp!

The numbers in the afr tables are basically Holden's numbers offset to suit different fuel, so you are assuming they got it right

[antus]

Rule of thumb for petrol is 14.7 for stoich, maybe up to worst case 15.8 or there abouts for lean cruise (worse emissions, runs hot, watch your temperatures), and about 12.5 for max power off boost, or about 11.5 for max power on boost. Thats only rule of thumb but you can convert it to lambda or e85 to get an idea of the ballpark you want to be in. The AFR tables DONT take in to account the built in acceleration enrichment, deceleration enleanment or lean cruise so its best to leave the AFR tables as is, and then do a wide open throttle pull and watch what you get on the wideband, then tweak the AE tables to suit. Note that many other brands of EFI (some subaru, nissan) ive seen dont to enrichment thing, they just wind up the richness as you wind up the RPM. Thats not the way to go on the delcos as they are smarter than that. For the most part, if you leave all the modifiers stock (or what Holden202T has given you, which is an adaptation of stock for E85 and then set the VE table table injector rate you should find its pretty good under all the mentioned operating conditions.

[Holden202T]

there are one or two exceptions to this, for example, 14.7 -> 6.4 = methanol stoich .... but if I run my car on 6.4 at cruise its too lean, I don't think its big cam related, I think its just that methanol needs to run a bit richer to be happy!

now im not sure if E85 is at all like this or not but you'll be able to answer that soon enough

[TdracerTd]

I'm looking at booking some dyno time soon, so, no doubt I will have even more questions. Although, I think a lot will become clearer too. Most of my problem is not being able to get a log because the car can't be driven on the road, so the more I think on it without practical experience, the more, what seem like, stupid questions come up.

I do appreciate your patience and help though.

[TdracerTd]

I found this-

http://www.hotrod.com/techarticles/engi ... en_sensor/

I think I understand the whole lambda number thing now.. My understanding is that if your gauge is set to petrol, it will read 14.7 at stoich on any fuel, but when you move away from stoich the actual reading is different from what the gauge reads?

I know that my afr tables in my tune are now set to e85 Afrs and my wideband is now sending the correct Afrs to the ecu, therefore I just need to adjust the ve tables so that the actual afr is the same as the desired afr, right? But I need to understand this whole lambda thing, simply because I must!

[Holden202T]

that table on that page is handy, as it shows max power rich and lean values, so you can get an idea of where the safe limits are for what your doing.

you are correct that if you want to get the VE table to match the commanded you need to adjust it till the wideband reading matches target AFR ....

also just to confuse things a bit more for you so what I have done below is showing firstly a E85 AFR table that I found in a tune .... its probably fairly similar to yours, and this is what your target AFR's are going to be in your data logs.

E85 AFR Table.jpg (253.59 KiB) Viewed 3953 times

now this next picture is the same table divided by 9.7 (E85 Stoich Value) to show you the lambda equivalents which might help you understand it better.

Lambda AFR Table.jpg (247.61 KiB) Viewed 3953 times