Data Log Reading Help

[GhostC6]

I am having problems reading and understanding the logs, and what changes need to be made. Can someone help me read these and understand what needs changes. I did see that under WOT the fuel trims go to a negative number, does that mean I need to add fuel or I dunno, I am lost. I lean if someone explains it to me but I need some help. Thanks guys and gals, I will post two files to use as examples to help me learn from, thanks.

[Move'n Up]

Negative means it's pulling fuel out.

[joecar]

The LTFT's are not updated during WOT (they are carried over into WOT from before WOT if your were running in CL)...

you really should check this using a wideband.

As Move'n Up said, negative LTFT's mean the PCM is removing fuel, it is doing this because the VE and/or MAF tables (whichever one is being used at that moment) are over-reporting air.

[statesman]

The LTFT's are not updated during WOT (they are carried over into WOT from before WOT if your were running in CL)...

Correct me if I'm wrong... but I think only positive trims are carried over, negative trims are discarded. He shouldn't be seeing negative trims during WOT.

[joecar]

Correct me if I'm wrong... but I think only positive trims are carried over, negative trims are discarded. He shouldn't be seeing negative trims during WOT.
Very good call :cheers:

yes, correct, negative trims are discarded (so fuel will never be subtracted at WOT), and he should not see negative LTFT's at WOT...

I wonder what is going on in his PCM.


The log filename indicates it's an E40, I wonder what's different compare to the 0411...?

[GhostC6]

Very good call :cheers:

yes, correct, negative trims are discarded (so fuel will never be subtracted at WOT), and he should not see negative LTFT's at WOT...

I wonder what is going on in his PCM.


The log filename indicates it's an E40, I wonder what's different compare to the 0411...?

How do I add a wide-band to my Autocal and can I get just one or do I need 2, one for each side? My headers have bungs for them and I also have the rear O2 bungs since I am not using cats. This is on a 2005 LS2 Corvette with 4L65E Transmission, PCM is the E40 and the TCM is the T42.

So my question is based on these, to get more power does it look like it needs more fuel, more or less timing, or can you even tell based on this or is a wide-band needed to determine that. And as I said, how is a wide-band connected to the Autocal?

Thanks again, so if I should not see the negatives, then why am I? What do I need to look at to see if I need to add or remove timing or fuel? Thanks in advance. Hope that info helps.

:book: