Comparing 2 logs with different timing.

[05gmcsierra]

im going to the track on sunday and im trying to dial in my tune.. at this point i wont be able to make it to the dyno to check at what timing i make the most hp but i did log 2 runs one with 28* anthter with 30*.. being fairly new at tuning i cant really compare and tell which one is better.. i know many great tuners out there can. was wondering if anyone can take a look at it and let me know what they think? its a 5.3 on 227/232 609/598 112+2 cam and 4k stall on a 4x4 ecsb.. really appreciate it thanks1412114122

[05gmcsierra]

Any help?

[joecar]

Your O2 sensor voltages at WOT indicate you're not sufficiently rich enough to be safe;

with 30° of timing advance you're dangerously close to combustion chamber damage;


the second log shows knock with 30° advance...

the first log shows no knock with 28°, I like this better.

[05gmcsierra]

Joecar I have an Afr on the truck its reading about 12.9 at wot

[joecar]

Try going a little richer, try to get the wideband to read 12.6.

[05gmcsierra]

OK... I'll b at the track again tomorrow to compare... my question is what log looks better the 28* log or the 30*? I'll ad more fuel later tonight

[joecar]

I like 4k28 better.

[05gmcsierra]

Thanks... I liked that one too.. looks like my grams/cylinder seem a bit higher.. I'll do a richer pass and log tomorrow... thanks joecar

[05gmcsierra]

Joecar sorry hadnt driven the truck since i got my DD driver now but finally took it for a spin loaded the 28* tune and got my wideband reading 12.5-12.6 and this is what i got.. looking at it by my personal experience it looks much better let me know what u think.. thanks..14188

[05gmcsierra]

any get a chance to look at the latest log??? i think thats gonna do it. truck doesnt feel to much different but log looks better than the 30* log... AFR reads all the way up to 12.4 at points but stays in the 12.6 area

[joecar]

I'm sorry I had a very busy week, I'll look at it tomorrow (I sent myself a pm to remind me).

[joecar]

HO2Sx1 show that you're not sufficiently rich at WOT ( however you need a wideband to tell you exactly how lean it is )

and with 28° of timing this means the combustion chamber temps may be dangerously high (even if knock is not detected/reported)...

[joecar]

MAF has some large fluctuations, seems like the PCM is filtering/smoothing it.

[05gmcsierra]

JoeCar where should my HO2Sx1 be reading? i do have a wideband i just dont connect it to efi live when i log. but like i said wideband reads from 12.4-12.6 from 0-100mph.. i might need to calibrate it again. i have the Lc-1 innovative.. with the MAF having large fluctuations what can be done to fix it?

[joecar]

I like to see HO2Sx1 read 920+ mV at WOT.

[joecar]

What fuel are you using...?

[05gmcsierra]

I'm using 91.. out here 870-890mv is where we like to c it.. my wideband is reading 12.6.. 920s would make it read in the 11.8.. which is a bit rich for an NA truck

[joecar]

Is your fuel E00/gasoline or E10...?


You can't really correlate between wideband and narrowband like that (you will find that 900-920mV will be close to 12.5)...

anything less than 900mV usually is lean (but not necessarily).

[05gmcsierra]

I'll log with my wideband connected to EFI next time...so u can c what I mean by its running 12.6 AFR