Drop in Injector Pulse Width for no apparent reason, please help.

[mn_vette]

I'm having some weird going on. I have a log of a lean area in my WOT pull. I have tons of other pulls that things are fine. Looking at a good log and the bad log the path through the VE table is pretty close. Maybe the cells are different by a percent or two, but not 20% like the wideband error is telling me. My first thought was I have a fuel system issue, but the injector pulse widths are low as well. The other thing that is low is the cylinder air mass. And at some point in each pull things just kind of fix themselves(red arrow in bad pic). I attached two screen shots, one of the good and one of the bad, at the same exact RPM and MAP reading.

The only thing I can think of is that the coolant temp is messing with things somehow. The bad pull is 207 vs 189 in the good. I also don't have my injector tip table set. But in both cases, why would the bad run fix itself half way through? The "fixing" seems to happen at 4200 rpm in several of the pulls.

I ran the car again yesterday and the problem seems to have gone away for the moment, or I did not happen to hit the correct conditions for it to reproduce. Any thoughts or suggestions would be greatly appreciated.

The car is a 2012 Corvette with a stock LS3 and a vortech supercharger. Currently setup to run SD only.






22_05_19_2BarOS_correctedMAP_7.hpt
22_05_19_BadStuff_7.hpl
22_05_19_Back_7.hpl
Good_pull_snip.JPG
Bad_pull_snip.JPG

[hjtrbo]

Don't think the MAF is failed properly.

Engine Diag -> Airflow ->
Mass airflow fail high: 2
Mass airflow fail high: 1


High count threshold: 1
Low count threshold: 1


Engine Diag -> DTCs
P0101: Fail on first error
P0102: Fail on first error
P0103: Fail on first error

[mn_vette]

Don't think the MAF is failed properly.

Engine Diag -> Airflow ->
Mass airflow fail high: 2
Mass airflow fail high: 1


High count threshold: 1
Low count threshold: 1


Engine Diag -> DTCs
P0101: Fail on first error
P0102: Fail on first error
P0103: Fail on first error

I thought just dropping the FAIL HIGH to 1 would cause a failed state. Every time I logged MASS AIRFLOW SENSOR STATE the value has always been MAF FAILED. I guess I haven't re-checked it since upgrading to the 2 Bar OS. I also have DYNAMIC AIRFLOW HIGH RPM set to 8000 RPM. But even if it were switching to using the MAF, what would cause it to calculate 20% less fuel on one run compared to an earlier run on the same flash?

I've been digging into these logs and the tune to find anything that would explain this. I did notice that my Ambient Air Temps are in the 30's for some reason. I'm not sure if Ambient air is used for anything. IAT seems correct. I also noticed that I did not have two of the OS patches applied. Speed Density Air Mode and Manifold Vacuum Boost.

[mn_vette]

Don't think the MAF is failed properly.

I adjusted the MAF failed numbers. I did not mess with the DTC's, but I will switch them to "MIL ON FIRST ERROR". They are currently set to "NO MIL LIGHT" or "NO ERROR REPORTED".

So..........If I start the car the MAF is failed. If I turn the car off and immediately restart the MAF is "No Fail". Is this normal? It seems very odd if it is.



So with the MAF working, I'm confused as to when/why it changes the Air Calc Mode to Hi Speed. Is this transition something different from the Dynamic Airflow Disable RPM? Maybe I'm not understanding the modes correctly or loging the right things.



I also can't add Air Calc Mode to my charts. Is there some way to plot the enumeration variables on the graphs? I've been searching but haven't found anything.

[blindsquirrel]

If the MAF DTCs have not been fixed yet, yes, it's normal for it to not work right.