Hi guys, I just have a quick question/s. I baught HP Tuners a couple of weeks ago to tune my '00 SS. I would like to run E85 and was wondering, what changes have to be made computer/tuning wise in terms of peramiters and such? I know the stoich has to be 9.7, I believe it was, but how do you add more fuel and air?

I'm not here to start another, "why e85 isn't worth it," thread either.

 

Anyone?

 

You don't need to put stoich to 9.7:1. I've never used HP tuners. In efi live the easiest way to convert your existing tune to e85 is to decrease the flow rate values of your injectors by about 25%.

Thus take all the injector flow informaiton and multiply it by .75. This is a cheap and easy way to do it. Essentially the PCM thinks your injectors are smaller then they really are, and will give it more fuel.

I've done it both this way and trying to make a tune from scratch to run on e85. Trust me, doing the injector method is the easy way.

 

Wrong.

Change the Stoich ratio to get fueling correct. The best method is to get a tester to find the E content of the fuel and then use the corresponding stoich ratio in the tune to match your fuel type.

Even once this adjustment is made you will still need to go over your airflow tables to get them within error just due to the differences in burn rate, efficiency etc. You'll also have to tune your timing tables to taylor to the better fuel. The biggest thing is make sure all your fuel components are up to the task. You'll def need larger than stock injectors and fuel pump and lines will need to be E85 compatible.

 

Correct. Set the stoich to represent what blend you are running (actual blend 70-80% likely). Normally 9.8 to 10.0 for stoich with most pump e85 depending on time of year. Leave power enrichment as is. lambda is lambda, doesnt matter if the table is displaying 12.6 or 13.0. Its all eq ratio.

Just change the stoich, and start by adding about 3-4* of timing.

 

Doing it via the stoich multiplier or cutting down the injector flow rate accomplishes the same thing. One just reports differently in the scanner for AFR values.

 

So all I do is change stoich and add timing and should be set to go? I don't change injector tables, or any other tables?

 

Your right. I'm so far off that all these vehicles I have tuned on e85 must all be blown up from running to lean!!!!!!

In reality it is much easier for most to switch to lambda, because air/fuel ratio's will confuse people who are not use to them. Me personally I have and like using a gas air/fuel ratio to tune everything with, because this is how I have done it for the last 10 years. Plus a lot of gauges only read on gas air/fuel, thus my lc-1 will always show 14.7 no matter what fuel is being used, but cause that is lambda of 1.

There is more than one way to skin a cat.

Also unless you are a top tier tuner going for some sort of record you don't really need to get a tester and test every batch of e85. I have done that. Are their variances? yes, but they won't make enough of a difference. Set the tune up a little rich and run it that way. E85 is much more forgiving than gas, and you can run much richer and much leaner than gas with less affects.

Just my $.02 from tuning many different engines on e85 over the years.

 

You can accomplish correct fueling either way however I personally want to input into the PCM the parameters that are correct. The flow rate of the injectors is a given, the stoich ratio of the fuel being used is a given. So input those givens into the tune so that there are less variables to deal with. Otherwise you might as well start raping the PE table to get desired fueling at WOT.

I do everything in Lambda because of all the different fuel types I tune, def makes life easier.

 

You also need to tune the cold start, because E85 is harder to start in cold weathers than pure gasoline

 

I've been looking for the "stoich" table on my '00 SS and can't find the table, any help on where to find it?

 

Can anybody help?

 

vcm editor>engine tab>fuel control>general> stoich is uppermost & leftmost blue tab under air fuel ratio heading

 

So it would be the "decay delay" tab?

 

Sounds like you're in the wrong view.

Go to the top of the screen, click "Edit" then "View" and make sure "Advanced" is checked. Then go back and look for the stoich tab under "Fuel" and "General".

 

I'm going to try that later on today. Merry Christmas to all.

 

Ok, this is the information I needed to finally find it. Thank you very much for your your help.

 

For the timing, i can start off by adding two degrees on all the timing tables, or just the high octane table, i believe it is?

 

I wouldn't mess with timing much at all until you verify fueling. Low engine speeds where timing is already advanced alot will not need to be advanced as much as it does under load. The cold start regions need to be advanced because E85 is terrible in a cold engine.

 

I'll take a look at the cold start area. It doesn't really get that cold out here in the Bay Area.