LSJ E85 conversion

[mike_sno]

Hi Forum,

as I am on the path of converting to E85 I have so many questions. I thought an own threat would be the best way instead of putting it on my build log.

Currently I want to figure out if my fuel system is good enough. On Hp Tuners and Cobalt Forums, you read that the fuel pump is good. However, I have the LAP fuel pump, not the LSJ.

My idea is to just poor some E85 in the tank, connect the fuel pressure gauge to the rail and see how bad it is.

In order to do the minimal tune to E85 is it sufficient to change the AFR ratio to 9.5 and add a few degrees (maybe like 4?? ) of timing due to the slower burn rate?

 

[G Atsma]

One thing to consider about E85 is that it isn't always 85% ethanol. The ratio can be all over the map. This is why engines so equipped have flex fuel sensors. Unless you KNOW the exact percentage of the E85 your using, BE CAREFUL.

 

[Ross]

I'm not sure where you can get an LAP E85 tune, but I would try to find find one if I was you.
Check if other cars have your 32-bit computer E37 engine control module that the LAP is using.
HP Tuners has a compare tune feature, that will give you some good ideas on things you may want to add to your tune.

 

[mike_sno]

I have the LSJ computer, just the LAP Fuel pump and filter.

 

[Ross]

There are a few E85 LSJ tunes listed on post 1 of my build thread.
Check out what others have done compared to your tune!

 

[mike_sno]

Did the test run today. Simply changed the Stoich and that's it. Overall my tune is very rich in PE.(Was it already with my gas tune) Watched my wideband and the Fuel pressure. Fuel pressure dropped to 50psi under worse case conditions and I noticed the pointer on the gauge was shaking quite a bit.

Injector DC up to 108% again. But still I could not see that the wideband picked any of that as a lean condition up. Maybe it's because it such a short time when I am at 7000rpm and high boost before I switch gears.

I think at the moment I can keep my current set up. Fuelpump, Injectors might be at the maximum, but for the moment it works.

Added 2 degrees of timing and still don't see any knock. Next I will lower the PE, as this should help me also with the Injector DC and the fuel pressure.

 

[Ross]

I know the LSJ can benefit from bigger 12V power wires to the fuel pump, and wonder if the LAP is the same. A voltage measurement at the fuel pump would confirm how much voltage drop the fuel pump has. It is a cheap fix to get some more fuel pressure out of the existing pump.