Ethanol / E85 hard starts on DI engines

[Sneakyws6]

Has anyone had any luck on what causes the hard starts, or I should say stumbling starts when the Ethanol rating gets up over E75 on the DI engines? I had my 2017 Camaro SS on E85 until I went the Procharger D1SC route, I recently converted my 2016 GMC Sierra 6.2 over to E85 as well. Now that I finally have the Ethanol over the E80 point I am seeing the 1st initial start of the day stumbles a bit before it catches. The Camaro did the same thing when it was on Ethanol as well.

Is this a start up timing issue or fueling issue? Every start after the 1st one is normal, unless the vehicle sits for 6-8 hours or more.

Anyone have any input or suggestions?

Thanks... Todd

[kingtal0n]

I think its because the fuel has a hard time vaporizing when everything is cold.

Maybe pour a cap full of gasoline into a vacuum line first thing, then wait a moment for it to evaporate. "gasoline prime"

[Sneakyws6]

Yeah not going to "prime" the system every time. It is a tuning issue for sure.

[HackAbuse]

Do your tunes have tables for transient fueling or no?

[kingtal0n]

If you think its a fuel issue then why not add fuel to the cranking pulse / prime


After the computer sends its initial prime to all injectors after fuel pressure delay, why not give it 45 seconds+ to see if the fuel will more fully evaporate, because evaporation rate is slow


these idea are for you to make further analysis. Not necessarily permanent solutions. What each test reveals is something about the issue.

[TriPinTaZ]

Can you post your tune? Your startup tables likely need to be adjusted.

[Sneakyws6]

Here is the current tune. I am thinking the fuel table for cranking eq ratio alcohol needs some more fuel in the .4 fuel pressure table from -40* to 60* area of the table.

[07GTS]

can also try less timing closer to 0-5 deg when cranking on ethanol so that the cylinder is under more compression at top to give a better environment to fire, mine isnt DI but i find around 5 deg works good on mine for the colder temps so its worth a test

[TriPinTaZ]

I took a look at the tune, nothing seems way off. I agree with a little more fuel and a little less timing to get it to start quicker.

[killercolt]

Here is the basic. Most cars have an after start enrichment that give the cars extra fuel for a few seconds or minutes. On your car, the section you want to tune is under Air flow->General->Cranking Airflow and Torque->Base Air Flow. Highlight the whole Base Air Flow table and multiple it by 2. You can lean or richen it later with other numbers or multipliers but start with doubling the numbers and watch the initial start up AFR.

What this will do is give you extra fuel on the initial start up to catch the idle. Tune it to get the car to start up at 12-13:1 AFR and then the car should transition to 14-15:1 AFR after the. You want to do this with some cammed cars too because it will need that extra fuel to stabilized the idle during initial start up. Really it can be apply to any cars that need extra fuel after the first few seconds or minutes of start up. Good Luck.

[TriPinTaZ]

Here is the basic. Most cars have an after start enrichment that give the cars extra fuel for a few seconds or minutes. On your car, the section you want to tune is under Air flow->General->Cranking Airflow and Torque->Base Air Flow. Highlight the whole Base Air Flow table and multiple it by 2. You can lean or richen it later with other numbers or multipliers but start with doubling the numbers and watch the initial start up AFR.

What this will do is give you extra fuel on the initial start up to catch the idle. Tune it to get the car to start up at 12-13:1 AFR and then the car should transition to 14-15:1 AFR after the. You want to do this with some cammed cars too because it will need that extra fuel to stabilized the idle during initial start up. Really it can be apply to any cars that need extra fuel after the first few seconds or minutes of start up. Good Luck.

^^^ This is much better advice than I gave. I would also try reducing startup timing by 2 degrees if this doesn't completely solve your issue.