4.8 Hot Start and Fuel Trims / VVE

[DanN]

I will test that tomorrow, row by row.

"Tomorrow" was a few days ago now, but it appears that when you have the tune set to "Manual", only the neutral row is used. I haven't gone for a long drive with it, but this works "around the block".

If you have a fancier transmission that had a TCM, it may well use all the rows - but for my "dumb" AR5, it only seems to use the neutral row.

My current Minimum Final Idle Airflow Minimum table:

FIAM-Neutral.png

[LS ROB]

Did you happen to get a log? I'd be curious to see if the throttle blade is still active with the new airflow numbers. I would have thought that the whole airflow table is "supposed" to be used unless the ECM defaulted to the P/N row if something isn't jiving. Do you have a clutch position sensor?

[DanN]

Did you happen to get a log? I'd be curious to see if the throttle blade is still active with the new airflow numbers. I would have thought that the whole airflow table is "supposed" to be used unless the ECM defaulted to the P/N row if something isn't jiving. Do you have a clutch position sensor?

I did. I'm curious what you find.

I did wire in the clutch circuit that the P12 used to the E38, but I'm not sure it's actually doing anything, or how to tell in the tune. Electrically they appeared to be the same, so I expect it does "work", for whatever that means.

DN-Lly17-FIAM-Neutral Only.hpt
DN-Jly17-FIAM-Neutral Only.hpl

[LS ROB]

I would start back over on this. The Airflow table cant be helping you at all and it looks like to me that you have misfires when going WOT. Check all of the plugs, plug wires and coils to see if they're all snugged up. I wouldn't do any WOT stuff until you get the VVE and MAF heading in the right direction. Maybe someone with more experience can verify the misfires.

[DanN]

I would start back over on this. The Airflow table cant be helping you at all and it looks like to me that you have misfires when going WOT. Check all of the plugs, plug wires and coils to see if they're all snugged up. I wouldn't do any WOT stuff until you get the VVE and MAF heading in the right direction. Maybe someone with more experience can verify the misfires.

I thought my MAF was pretty good, but perhaps my charts are bad. I've looked at the VVE a little bit, but haven't made any big changes.

The misfire is new. I'll dig into that for sure.

If someone with known good graph setups could show me my log in their tables, I could confirm if mine are any good. I could be dealing with garbage-in garbage-out here.

[DanN]

OK - I did some testing.

Idling in the driveway I was getting random misfires, and it would go OL -Fault.
I reverted the FIAM table to the old one. I still got misfires.
I reverted the whole tune back to one I had from July 15, and the misfires disappeared.
I changed the FIAM table back to the one I was using with only the Neutral row populated, and got no misfires.

So it appeared to me it was something in the tune that was causing the misfires, but I'm not sure by what exactly. Maybe my VVE meddling?

I decided to wildly change the VVE table - I exchanged the truck table for a Corvette one, and took 25% of it out right off the top.

I took it for a gentle cruise around the block - didn't get into WOT at all.
No misfires.
Hot started like a champ.
appears to be really, really rich.
Overall, felt pretty good.

Now I'm not 100% sure how to properly tune the VVE, but I think the MAF is ok - If someone would take a look and give thoughts / suggestions I'd happily drink a beer on their behalf!