what controls bpw at start up, $A1?

[LZeppelin513]

Are the 5 cranking fuel tables everything that controls bpw durring start?

My 3500 starts great when cold but when hot and after sitting for a bit, it starts hard. It will just crank and crank, then misfires, then finally catch and start. Or I can crank it a second, release, crank again and it starts up fast but still usually with misfiring.

I have tried adding and subtracting fuel from the "cranking fuel pulse width vs coolant temp" but have not been able to fix the problem. It seems I only make it worse when I play with this table.

Any suggestions?
Thanks

[Superdave]

That's it, the VS Coolant temp is the main table that handles it.


how big are your injectors?
What's your 0% EGR BPC set to?
What is the IPW during cranking?

[LZeppelin513]

OK, thanks. I have stock 3500 injectors which i believe are 24 lbs. I am running at about 55 psi fuel pressure.

My BPC is set to 115

I will have to look at the pw for cranking later today.

[LZeppelin513]

Final bpw at start is 30.08. 52 degrees F coolant (cold).

Started great

[LZeppelin513]

https://docs.google.com/open?id=0B5PFNNInFEsbWU4zaEVETDlFcnc

^ This is a .csv of the warm start. It only does this if it I let it sit for a bit after its warm and then try to start it.

It cranked from sample 13-15. At sample 16 it caught, but failed to start, and continued to crank for a bit until it caught and started at sample 26

[Superdave]

115 is WAY too low, I'd start off with a fresh bin file and set it to 150. You are going to make a ton more work for yourself having it that far off. 150 will make it driveable and then you can start making small changes to the tables from there. 115 is about right for 36lb/hr injectors.


You really shouldn't need to adjust the cranking fuel PW much at all. In all the 3400/3500 tunes I've sold over the years they all do fine with the stock values from the 3.1. I found one log from my old Cavalier with a stock 3400, cranking BPW was about 5ms at 225RPM and then down to 3ms at 900RPM.

[LZeppelin513]

Well maybe ill have to start over then at 150.

Im a bit confused though because I took the stock 3.1 BPC value of 153 and multiplied it by 1.13 to convert it from 3.1 l to 3.5 l. I then divided it by 1.44 to convert injector size. Robertisaar explained to me how to do this in another thread. This got me close to 115, why is 150 a more reasonable BPC? My tune is getting pretty close and my combined VE (base + main) at 4000 RPMS is in the upper 80s. This also "seems" reasonable. But i dont know... ?

[Superdave]

where did you get 153 from?

the stock 0% BPC value on a gen 2 3.1 $A1 tune is 224.

[LZeppelin513]

Could this value be different going from TP V4 to V5? I don;t know why it would but I got my stock 3.1 bins from here:

http://www.gearhead-efi.com/Fuel-Injection/showthread.php?391-1227727-1227730-ECM-Information-A1

I just downloaded one again to make sure and it is 153 at 0% EGR.

Is there a better place to get stock bins?

[Superdave]

I downloaded 2 files from his list, and tried them both in TP4 and TP5.. both were 224 @ 0% with my .xdf.

I also downloaded the V5 and V4 $A1 xdf's, the V5 wouldn't open in V5 but the V4 in V5 worked fine. There must be something wrong with his V5 .xdf.


If you want i can upload the latest version .xdf I use later on today, i know it works. lol

[robertisaar]

the odd numbers coming up is due to using the conversion GM suggested in the leaked A1 document.

X/1461.5

if using just the X conversion, then it makes a lot more sense, something i fixed in later XDFs.

[LZeppelin513]

I downloaded 2 files from his list, and tried them both in TP4 and TP5.. both were 224 @ 0% with my .xdf.

I also downloaded the V5 and V4 $A1 xdf's, the V5 wouldn't open in V5 but the V4 in V5 worked fine. There must be something wrong with his V5 .xdf.


If you want i can upload the latest version .xdf I use later on today, i know it works. lol

Thanks for checking for me I really appreciate it.

Dont worry about uploading it yet, it will be probably a week or so before i have enough time to start a new tune.

[LZeppelin513]

the odd numbers coming up is due to using the conversion GM suggested in the leaked A1 document.

X/1461.5

if using just the X conversion, then it makes a lot more sense, something i fixed in later XDFs.

Im not sure what this means.. Is the 153 value equivalent to 224 when using the later XDF? If So, do I treat it the same when determining a new value based on displacement and injector rate?

[robertisaar]

just change the conversion in the XDF to X instead of the weird divide, otherwise you'll have to do a lot of unnecessary converting back and forth.

[LZeppelin513]

OK thanks,

Now my BPC reads 168. Is this reasonable?