[mikenstang]

I am still tring to nail a start issue I have. My enging cranks a fires fine but immediatly after it fires if I don't open the throttle plate it will stall. This happends cold warm and hot. However it is better when hot. Once I have fired the car and cracked the throttle it idles perfect, a slight hunt when it is realy cold. It will idle with forced OL at 14.7:1 or so and it never hunts or stalls once in CL.

I don't know if it is an air or a fuel issue causeing the stalling after start. Any ideas on where to start???

[cgrey8]

Early on, my truck did this with the stock A9L tune. I found it was leaning out about 2-3 seconds after crank. It's stumble and run rough for about 3-5 seconds, then come back to life and stay that way. This only happened when cranking cold. Cranking warm never gave a problem. I enriched the Startup OL Fuel Table (FN1306) for the 1st 10 seconds of crank, and it has never done this since. Give that a try and see if that gets rid of the Cold Start Stumbles.

[mikenstang]

Thanks. That has appeared to have helped.I will run it a day or two to test it all various temps see if it needs any more changes.

[EDS50]

Early on, my truck did this with the stock A9L tune. I found it was leaning out about 2-3 seconds after crank. It's stumble and run rough for about 3-5 seconds, then come back to life and stay that way. This only happened when cranking cold. Cranking warm never gave a problem. I enriched the Startup OL Fuel Table (FN1306) for the 1st 10 seconds of crank, and it has never done this since. Give that a try and see if that gets rid of the Cold Start Stumbles.

Did you add or subtract to the values to enrichen the table and did you do it acros the board or just certain degrees?

[mikenstang]

For what it is worth I subtracted a total of 1.50 from the entire OL-Start up table in incremtents starting of 0.25. I took until the 1.50 before I was able to start and run without touching the throttle. However I did notice it got very lean about 10 sec. after starting, it was running around 17:1. So I added 0.25 back at 10 sec and above under 120*. Now it is around 15-16:1 until CL then it goes stabelizes around 14.7:1 It is much better now but I still need to drive and test for a few days.

[cgrey8]

I've done a few things with my tune with regard to fuel. I'll see if I can list them:

• I reset all columns in my Base OL Fuel Table (FN1307) to all be alike so there isn't a skew between the OL Fuel table and the Startup table.
• I setup the Startup Table to subtract from the LAMBSEs the amount I thought was needed. The values are in terms of AFRs so a value of 2.00 is subtracting 2 from whatever is in the Base OL Fuel Table. So if an ECT/Load value in the Base OL table was commanding 13.00 AFR, and the Startup Table said 2.00 for the same ECT/Time value, then you'd get 11 for LAMBSE (13-2). This made setting things up much more straight forward.
• I added the Stabilized OL Fuel Table (FN1360) to my tune using the FN1360 patch and configured it to switch from FN1307 to FN1360 at around ECT of 80°. It works really well. To read more on the FN1360 patch, make a search of the forum for FN1360 and look for the first thread where this was mentioned as a hack to the GUFx tunes.

Hope that helps...

[EDS50]

I've done a few things with my tune with regard to fuel. I'll see if I can list them:

• I reset all columns in my Base OL Fuel Table (FN1307) to all be alike so there isn't a skew between the OL Fuel table and the Startup table.
• I setup the Startup Table to subtract from the LAMBSEs the amount I thought was needed. The values are in terms of AFRs so a value of 2.00 is subtracting 2 from whatever is in the Base OL Fuel Table. So if an ECT/Load value in the Base OL table was commanding 13.00 AFR, and the Startup Table said 2.00 for the same ECT/Time value, then you'd get 11 for LAMBSE (13-2). This made setting things up much more straight forward.
• I added the Stabilized OL Fuel Table (FN1360) to my tune using the FN1360 patch and configured it to switch from FN1307 to FN1360 at around ECT of 80°. It works really well. To read more on the FN1360 patch, make a search of the forum for FN1360 and look for the first thread where this was mentioned as a hack to the GUFx tunes.

Hope that helps...

When resetting fn1307 is there a preferred number to start with to all be alike?

[cgrey8]

Here's what my Base OL Fuel Table (FN1307)Looks like now:

12.35_|_12.35_|_12.35_|_12.35_|_12.35_|_12.35_|_12.35_|_12.35_|_12.35_|_12.35
12.70_|_12.70_|_12.70_|_12.70_|_12.70_|_12.70_|_12.70_|_12.70_|_12.70_|_12.70
13.27_|_13.27_|_13.27_|_13.27_|_13.27_|_13.27_|_13.38_|_13.38_|_13.38_|_13.27
13.27_|_13.27_|_13.27_|_13.27_|_13.27_|_13.27_|_13.38_|_13.38_|_13.38_|_13.27
13.27_|_13.27_|_13.27_|_13.27_|_13.27_|_13.27_|_13.38_|_13.38_|_13.38_|_13.27
13.27_|_13.27_|_13.27_|_13.27_|_13.27_|_13.27_|_13.38_|_13.38_|_13.38_|_12.92
13.27_|_13.27_|_13.27_|_13.27_|_13.27_|_13.27_|_13.38_|_13.38_|_13.38_|_12.92
13.27_|_13.27_|_13.27_|_13.27_|_13.38_|_13.38_|_13.38_|_13.38_|_13.38_|_13.38

The columns are not identical, but they aren't nearly as different as the stock values are. And the tend to make more sense than the stock values. The column scaling is stock, however the row scaling has been updated since I run Load%=Load. I configured this table's Load values for each row to look exactly like my spark tables. There's very little thought put into the non-WOT numbers other than they seemed to work well during crank which is the only time those values are referenced. The top two rows represent my WOT AFRs. Although once the ECT is up to 80°F, the logic uses FN1360 which controls the AFRs more granually than this table can since FN1360 is RPM/Load based, not like FN1307 which is ECT/Load based (no RPM component).

Here's my Startup OL Table (FN1306):
1.14_|_1.14_|_1.14_|_0.92_|_0.00_|_0.00_|_0.00_|_0.00_|_0.00_|_0.00
1.14_|_1.14_|_1.14_|_1.14_|_0.92_|_0.46_|_0.23_|_0.00_|_0.00_|_0.23
1.14_|_1.14_|_1.14_|_1.14_|_0.92_|_0.46_|_0.23_|_0.23_|_0.23_|_0.23
1.14_|_1.14_|_1.14_|_1.14_|_0.92_|_0.69_|_0.34_|_0.34_|_0.34_|_0.34
1.94_|_1.94_|_1.94_|_1.94_|_1.14_|_0.92_|_0.46_|_0.46_|_0.46_|_0.46
2.97_|_2.97_|_2.97_|_2.17_|_1.60_|_1.26_|_0.92_|_0.57_|_0.57_|_0.46
4.00_|_4.00_|_4.00_|_3.66_|_1.94_|_1.60_|_1.26_|_0.92_|_0.92_|_0.80
2.97_|_2.97_|_2.97_|_2.97_|_2.97_|_2.63_|_1.72_|_1.72_|_1.72_|_0.92

Notice, I have the top row going to 0s when ECT reaches 90°. And at running temps, it zeros out even earlier in the startup process. The column scaling for FN1306 is stock. However the row scaling is modified so that the top row corresponds with 30 seconds after crank, not 45 seconds after crank.