Cold start problem

[jmardlin]

I am having an issue with cold starts on my Cruze. It has a flex fuel conversion. When I run E85 it starts hard the first start after sitting with the engine cold. The cranking fuel tables make no sense to me in the E78 ecm. So needless to say I can't figure out why it won't start well. I am guessing that it isn't getting enough fuel while cranking cold.

[TCSS07]

increase the numbers to add cranking fuel and decrease the numbers to remove cranking fuel. add 10% to the ect areas that are giving you trouble and see if it helps

[jmardlin]

My problem is mostly the way they set up the table. The format isn't a standard pulse width for a given temp. On the L78 ecm like in a 1.4l Sonic or Cruze it is different. I can try adding to the numbers. I got looking at the table and it doesn't even look like GM set the E85 cranking table up correctly as temp go down the numbers go up then down and back up again. I think this is what is causing the issue. I think I will have to fix that part of the table and see what it does.stock 2015 Cruze turbo manual.hpt

[Dutch]

Could you PM me the tune you're using thats giving you trouble?

Adjust the Fuel/General/CrankingFuel/CrankingFuelEqRatioAlcohol table to match mine.
Rescale the X axis to match whats shown.
Capture.PNG
Do not just blindly add 10% to the entire table or you'll have starting issues when its hot.

There may be other parameters that have to be adjusted as well.
GM sometimes sets the starting spark too low - but DO NOT change that without consulting with me first.

Also, in Fuel/FlexFuel/General
You will need to set FlexFuel to ENABLE for the ECM to actually use the e85 parameters.
Set FuelSensor to VIRTUAL if you want it to try and guestimate ethanol concentration from fuel trims.
I personally do not recommend this because:
- you need larger injectors if you want to make more than stock power with e85, and it is close to impossible to get the data dialed in close enough to make this feature work properly.
- it sometimes decides to be stupid, particularly when you switch between gas and e85.

Set FuelSensor to SENSOR if you installed an E85 sensor.

In either case, I highly recommend that, before going nuts, you first test it by filling up with either e15 or 1/2 gas and 1/2 e85 to see if the reported percentage makes sense.

You can also just force the ECM to use the ethanol parameters by simply overwriting the gas parameters with the ethanol ones, and setting to stoich to something like 9.85.
If you go this route i recommend you test the local stations in your area, and consult pages 35 and 36 of the department of energy's E85 handbook to set the stoich to something appropriate.
https://afdc.energy.gov/files/u/publ...l_handbook.pdf