e85 tune question

[lsxfoxbody]

ok guys I know stoich for gas is 14.76 and for e85 is 9.76 so why would my tuner put 10.50 for e85? I am new to tuning but I also took the tuning school course and now that I look at this tune I'm don't understand some of the things. like I said I'm new to this but took the course to be able to tune the car myself. ive paid over 2k in retunes and its been the same thing everytime. car is a 06 gto ls2 with ls3 top end. heads milled to 63 ccs and fully cnc ported and gpi intake ported and rod mod. tb is also ported. full bolt ons. 4000 stall. 3.90 gears. now this tune that I'm gonna attached is before heads were milled to 63ccs and head gasket from .54 to .40 thick. to bump up my compression to 11.5. cam is custom grind 239 254 so its big. I did a lil log just drove it around for first time just to get a feeling for it and it sure feels different. I'm gonna attached the files and see what you guys think and what you would do different. I want to try do it myself with your help before taking to another tuner. like I said its on e85. thanks in advance

[5FDP]

It is E85 from a barrel or it is E85 from a pump at the local gas station.


Pump E85 is never really "E85", you are lucky if you can get it between E70 and E80 during the summer and E50 during the winter months. Him putting it at 10.50 for stoich is right in line with running fuel from a local gas station. He is just playing it safe by making stoich around that E70-E80 mark if it's not from a barrel.


You log shows that bank 1 has an issue, your fuel trims are showing this. Look at how the long term trims somtimes max out at +25% and your short term trims go way positive as well. I'd be looking for a possible vacuum leak or exhaust leak pre o2 sensor on that side that might be causing this issue.

Try to get your wideband o2 sensor included into your logs for when you start doing tuning this more, you will need that information.

[lsxfoxbody]

might be an exhaust leak. I think I can hear it too. I will get that checked out tomorrow, and get a log with wideband. should I do a part throttle log or full throttle. I keep an eye out and just make sure everything is good before going wot ! thanks alot

[lsxfoxbody]

I see fuel cut off is at 6700 but my wot shift point is at 6750 sometimes i hit rev limiter especially the only time i sprayyed the 100 shot. Should i put it at 6800 for fuel cutoff ?

[G8GTNOOBIE]

dumb question but why is the timing locked at 25 across the chart?? wouldn't you want to tune it n/a first and then adjust the spark for the spray??

[Lakegoat]

You can enable flex fuel and install a GM flex sensor on that GTO. Then you can let the sensor determine the E amount. Of course, there are more tables to tune doing that.
You don't want fuel cut at wot while you are spraying nitrous. I can send you a picture of that. Make it 7000rpm. In controls, fuel cut is disabled, so I don't know what is limiting the rpm--didn't look any further.

[lsxfoxbody]

Its is tuned for NA

[lsxfoxbody]

You can enable flex fuel and install a GM flex sensor on that GTO. Then you can let the sensor determine the E amount. Of course, there are more tables to tune doing that.
You don't want fuel cut at wot while you are spraying nitrous. I can send you a picture of that. Make it 7000rpm. In controls, fuel cut is disabled, so I don't know what is limiting the rpm--didn't look any further.

Ok ill go from 6700 to 7k on that

[lsxfoxbody]

It is E85 from a barrel or it is E85 from a pump at the local gas station.


Pump E85 is never really "E85", you are lucky if you can get it between E70 and E80 during the summer and E50 during the winter months. Him putting it at 10.50 for stoich is right in line with running fuel from a local gas station. He is just playing it safe by making stoich around that E70-E80 mark if it's not from a barrel.


You log shows that bank 1 has an issue, your fuel trims are showing this. Look at how the long term trims somtimes max out at +25% and your short term trims go way positive as well. I'd be looking for a possible vacuum leak or exhaust leak pre o2 sensor on that side that might be causing this issue.



Try to get your wideband o2 sensor included into your logs for when you start doing tuning this more, you will need that information.

I had a leak right after header, on bank 1. Ill go and fet another log today. Leak has been fixed

[Lakegoat]

Looks like your injectors (IFR) are set up like a return system. Your offset VAC is set up like a return system ?

[lsxfoxbody]

Looks like your injectors (IFR) are set up like a return system. Your offset VAC is set up like a return system ?

Im not really sure what you mean ?

[lsxfoxbody]

I see what you mean, should it be on vacuum or map ?

[Lakegoat]

Your IFR is the same across the board like a return system. Your voltage is increasing like stock. Normally when the ifr is a flat line, so is the voltage. Do you have a return fuel system?

[lsxfoxbody]

Your IFR is the same across the board like a return system. Your voltage is increasing like stock. Normally when the ifr is a flat line, so is the voltage. Do you have a return fuel system?

No i dont think i do. Unless im missing something and dumb. But it only has one fuel hose to intake fuel rails which i guess its not a return system

[curiousg7]

I believe if the fuel is not a return then the IFR has to be scaled slightly above and below the flow rate depending on manifold pressure to account for the engine vacuum pulling or not pulling fuel out of the injector

[07GTS]

its if ur fuel pressure is vac/boost referanced or not, if it is referanced then the reg changes pressure with vac/boost so ur tune dosnt have to, if its not then the tune has to adjust for the vac/boost

[Lakegoat]

I guess return was the wrong description. Isn't his flow rate supposed to be increasing in his tune---not just flat across?

[07GTS]

I guess return was the wrong description. Isn't his flow rate supposed to be increasing in his tune---not just flat across?

not sure if any of those had a fuel reg on the rail but u would see a return hose as u were mentioning i think its rare but some had it, if not tho it should be varing with vacuum otherwise will be chasing ur tail best to find a stock file with it setup to vacuum and just multiply it to suit your injector size at baro pressure then the rest should be close

[curiousg7]

its if ur fuel pressure is vac/boost referanced or not, if it is referanced then the reg changes pressure with vac/boost so ur tune dosnt have to, if its not then the tune has to adjust for the vac/boost

What would change with setups that are dead headed without a regulator vs return without regulator and then either of those setups WITH a regulator? Is the regulator the big thing to look for here as far as IFR tuning?

[07GTS]

What would change with setups that are dead headed without a regulator vs return without regulator and then either of those setups WITH a regulator? Is the regulator the big thing to look for here as far as IFR tuning?

its all to do with if the fuel pressure is referanced to manifold pressure or not, if rail pressure is constant then the tune table varies, if the rail pressure varies with manifold then the tune tables stay constant, all will have a regulator just wether its constant or varies