18 Corvette GS LT1 Speed Density

[joshua@arcflashllc]

Hey guys,
I have a 18 Corvette GS in for tuning. Trying to fail the MAF over to SD mode and tune VE table.

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2020-02-05_2324.png

I get the maf P0102 code and it def changes the A/F ratio so it appears to be in SD mode. However, when I make changes to VVE table it basically doesn't do anything. For example LTFT was -28 at idle so as a rough shot I multiplied that RPM and PR region of the VVE table by .75, calc'd the coefficients. No change in fuel trim. As a test I reverted back to the starting coefficients and multiplied that region of the table by 1.25 and again no change in the LTFT. This leaves me thinking either it's not really in SD mode or the VVE table is not mapped properly. From reading in this forum I've seen some of the more knowledgeable folks talk about SD tuning not working well on the newer cars. I've also heard mention on here of the VVE table not working properly.

It's peculiar because Greg discusses this method for tuning in his Gen V Tuning video. Any suggestions guys?

Thanks!

[Ben Charles]

Should post the tune... for VVE to be that far off I’m assuming it has a cam?

[Ben Charles]

Also can log MAF state, will show MAF failed or no failed

[joshua@arcflashllc]

Thanks Ben!

Cam, heads, intake manifold, intake, full exhaust and HPFP shim.

v006 is just a base tune with some idle tq updates, etc.. to get it to start and idle nice. 6a has the maf fail high fail freq set to 0hz and low to 14khz (not sure if the later is needed).

A/F is ~12.7 WOT on our dyno. Put down 519rwhp without any WOT tuning.

Just BTW I intend to tune the VVE table in OL with WB_actual_Lambda/Requested_Lambda feedback. I posted the LTFT example just to keep the problem at hand simple.

arcflash_v006.hpt
arcflash_v006a.hpt

[joshua@arcflashllc]

It does fail the MAF, so looks like that part is working.

[Ben Charles]

If in SD mode, of changes are not taking try to 0 out MAF table and then make sure you are changing fuel correctly in the right region...
gen 5 ECUs use pressure ratio instead of just Map

[Custom 68]

The gen 5 tuning is all new to me so this may be a silly question. Do you need to rest the ltft after the new tune is written? I didn't know how quickly they will repopulate.

[Ben Charles]

I personally don’t use them... but they do populate rather quickly

[Custom 68]

Since he had referred to them if they didn't get reset if it would give him some false info. Just a thought
Dave

[Ben Charles]

Most OS it does reset Long terms, but easy way to tell us scan key on before starting and see where your Long terms are at

[joshua@arcflashllc]

I reset the trims with VCM scanner during those tests. I also turned them off completely with VCM scanner and did clear the trims for WB Lambda Actual/Lambda Desired testing.

[joshua@arcflashllc]

Thanks Ben, I'll hop on the dyno in a minute and try zeroing out the MAF table.

I createded a PRxRPM graph with lambda % error and modified those regions in VVE. The PR lined up with the histogram so I feel pretty confident that I was hitting the right zones but I'll post up some screen shots when I test the MAF zero. I'm not above making dumb mistakes...

If in SD mode, of changes are not taking try to 0 out MAF table and then make sure you are changing fuel correctly in the right region...
gen 5 ECUs use pressure ratio instead of just Map

[joshua@arcflashllc]

Looks like zeroing out the MAF table did the trick. Thanks guys!