Just finished my COS tune and no start

[yzriders182]

No it doesn't smell like its flooding out or anything.

[joecar]

I just uploaded a COS3 tune and went through the tutorial and made all the changes it suggested. I also changed my data to match that of my injectors, but the truck won't start. It fires right away then just cranks. Shut the key off then try again and the same thing.

I attached my tune and any help is appreciated. Attachment 14794

Thanks

Does it run on the GM (non-COS) OS...?

[yzriders182]

Ok I made some head way today. I messed with the settings on the MAP and set C6301 to 98 and C6302 to 0. the map would read about 102 and would show vacuum when cranking. It started and ran well under these settings.

Only thing it would do is after running for a few it keep lowering the AFR down to about 13.0 then would stay down there. I shut it off for a few after running like that.

When I have the MAP in C6301 set to 190 it sees atmosphere at 105kpa but when cranking is showing more pressure.... how can I adjust that? what does C6302 exactly do?

Thanks

Here is the log from it running Cos3 start and run.efi
Here is the current tune that it works on. Riebel cos3 0001.tun

[yzriders182]

What does C6302 control? Would that help with the map seeing boost while cranking?

[joecar]

C6302 is the offset added to MAP after it has been multiplied by C6301.

Connect MAP sensor to various measurable pressure/vacuum sources and take note of logged value of SAE.MAP...

( you may have to work in psi or kPa depending on your gauge )

then you basically perform slope fitting by playing with C6301,2;

take several readings an post the results.

[yzriders182]

I see. How accurate of a pressure/vacuum source do i need? I have a vacuum/boost gauge in my truck but its just a cheap one.

I do have a vacuum pump would this work? what do you use?

https://encrypted-tbn1.gstatic.com/i...b0bmNY5TZAu8uw

[joecar]

That pump would work... but I would use a diagnostics vacuum gauge (one with better resolution, like Actron or OTC) .