When running E85, car struggles to cold start.

[TWS]

Gents,
Last year I installed a flex fuel kit on my 2010 ZR1, along with larger injectors (of course). We retuned it to run on both E85 and pump 93 and the car runs great... with one exception. The first start of the day, with E85 in the tank, the motor struggles to fire. It is only the first completely cold start of a day. Once warm she fires immediately. On another forum, I saw a well-known and respected tuner refer to this and say he knew how to modify the tune to make it cold start easier on E85. I emailed him asking for advice. He replied that he doesn't tune via email. OK, I respect that. He makes money from tuning and if he helps one guy for free or violates his policy of tuning cars in person... then the floodgates could open. So while I was disappointed, I understand. What his forum post did tell me though, is that the issue is known and the knowledge on how to fix it is out there.

Therefore I am appealing to the community to see if anyone has encountered E85 cold start problems on E38 and E67 ECM's and can advise me how to remedy. I imagine fixes would be very similar, if not the same, between the two.
Thanks in advance.

[GXPLS4]

Gents,
Last year I installed a flex fuel kit on my 2010 ZR1, along with larger injectors (of course). We retuned it to run on both E85 and pump 93 and the car runs great... with one exception. The first start of the day, with E85 in the tank, the motor struggles to fire. It is only the first completely cold start of a day. Once warm she fires immediately. On another forum, I saw a well-known and respected tuner refer to this and say he knew how to modify the tune to make it cold start easier on E85. I emailed him asking for advice. He replied that he doesn't tune via email. OK, I respect that. He makes money from tuning and if he helps one guy for free or violates his policy of tuning cars in person... then the floodgates could open. So while I was disappointed, I understand. What his forum post did tell me though, is that the issue is known and the knowledge on how to fix it is out there.

Therefore I am appealing to the community to see if anyone has encountered E85 cold start problems on E38 and E67 ECM's and can advise me how to remedy. I imagine fixes would be very similar, if not the same, between the two.
Thanks in advance.

Have you tried your cranking fuel vs. Fa table?a lot of people had sucess with 20% increase in fuel on the colder tenps

[mowton]

Gents,
Last year I installed a flex fuel kit on my 2010 ZR1, along with larger injectors (of course). We retuned it to run on both E85 and pump 93 and the car runs great... with one exception. The first start of the day, with E85 in the tank, the motor struggles to fire. It is only the first completely cold start of a day. Once warm she fires immediately. On another forum, I saw a well-known and respected tuner refer to this and say he knew how to modify the tune to make it cold start easier on E85. I emailed him asking for advice. He replied that he doesn't tune via email. OK, I respect that. He makes money from tuning and if he helps one guy for free or violates his policy of tuning cars in person... then the floodgates could open. So while I was disappointed, I understand. What his forum post did tell me though, is that the issue is known and the knowledge on how to fix it is out there.

Therefore I am appealing to the community to see if anyone has encountered E85 cold start problems on E38 and E67 ECM's and can advise me how to remedy. I imagine fixes would be very similar, if not the same, between the two.
Thanks in advance.

To help me better understand, have you installed a kit which is compatible with the PCM feature of Flex Fuel control of the Stoich as well as Open Loop tables? Has the tune been modified to enable this feature?

I am not that experienced in these kits and PCM programming. The E85 setups I have done were all reprogrammed knowing the fuel would always be E85 type. Higher alcohol content requires more fueling when cold due to reduced evaporation qualities until the valves get warm. You can see the difference in some of the OEM tunes that have both gas and alcohol tables.

I know Dave Steck had a great thread (and offered a flex fuel sensor) a while back but because some mis-represented his ideas as theirs, he pulled it down. Unfortunately I never got to see it.

Ed M

[TWS]

Have you tried your cranking fuel vs. Fa table?a lot of people had sucess with 20% increase in fuel on the colder tenps

Thanks! No, I have tried nothing to fix the problem so far. Finally just got off my butt to start gathering information before I go pressing keys in HP Tuners.

Ed M,
The flex fuel ability has been completely enabled in the ECM tune and the car was retuned on a dyno to take advantage. The only issue I have is the cold start.

[blkscooby]

Add 20-30% to the cold cranking fuel table. That will do the trick.

[mowton]

Add 20-30% to the cold cranking fuel table. That will do the trick.

So just to make sure I understand this flex fuel feature, wouldn't you add the increase to the Alcohol open loop tables in the open loop section to preclude over fueling when E10 is used and the warmer temps which seems to be ok? Wouldn't the goal be to just add a bit of fuel in the cold/alcohol region and blend to warmer areas. Are we trying to maintain the flex fuel capability?

Also, thought maybe doesn't apply, I have seen some tuners who set the IVT entire open loop table to 1.0 while tuning and some don't set them back to stock if delivering in closed loop. Just a thought. As a note, that is why I only set the IVT @ 133 and ECT @176 and up cells to 1.0 when tuning, to help with cold starts during the tuning process, if tune is going back to closed loop, then I return the IVT open loop table to stock.

Ed M

[07GTS]

all i changed was the first row in cold areas of the cracking fuel and that was enough to fix the e85 cold starts