Timing and Fuel questions

[2007chevy5.3l]

You think that just 100mV would make that much of a difference?

[2007chevy5.3l]

No hard feelings. Im actually trying to figure out and fix some of the things my first tuner changed. Some of the things he did were not good..

[Gregs]

You think that just 100mV would make that much of a difference?

oh you would be surprised, i did an experiment once with values similar to yours and it caused major problems with ltfts and since you have a flex fuel having really messed up fuel trims is going to cause havoc with the computer logic in regards to determining what percentage of ethanol is in your fuel.

i compared the tune you posted up with a stock version of that tune and i would set B3671, B1515, B1516, B1967-B1975, B2012 back to stock values.

[2007chevy5.3l]

Sounds like your on the right track.. Im going to try out what you suggest and see if the LTFTs straighten out..

[Gregs]

No hard feelings. Im actually trying to figure out and fix some of the things my first tuner changed. Some of the things he did were not good..

yeah did he setup the spark map? a general rule is that you don't want more than 3* max of change from cell to cell. its going like 10* of change over like 2 cells, i wouldn't mind seeing a good wot log to see what cells you are hitting. Was the spark map tuned on a dyno or guesswork?

[2007chevy5.3l]

It was pretty much all guess work. I set up the low load low thru high rpm values to 33* because it was 50-60* in those areas. I was getting KR so i kept lowering those cells till i got no KR and the engine felt smoother. Wot is fine. Im at 24.5* timing and 12.5 ish AFR with no knock

[2007chevy5.3l]

Gregs,

I changed the tables that you told me to change. Flashed it in, reset the fuel trims and went for some logging..
Heres what I got-

Tahoe fuel trim6.efi

[Gregs]

Gregs,

I changed the tables that you told me to change. Flashed it in, reset the fuel trims and went for some logging..
Heres what I got-

Tahoe fuel trim6.efi

fuel trims are much better now, looks like some fine tuning is left now.

[2007chevy5.3l]

fuel trims are much better now, looks like some fine tuning is left now.

Best I have seen them at yet!!

So just tune the Maf frequency Hz accordingly to bring the fuel back in? When tuning the trims do I watch LTFTs or STFTs? Or both?

[Dieselman]

Gregs,

I changed the tables that you told me to change. Flashed it in, reset the fuel trims and went for some logging..
Heres what I got-

Tahoe fuel trim6.efi

That looks heaps better