What am I missing. LS2 VE goes wacky when combined with MAF

[Stroked06Goat]

0804am VE takes a dive.JPG0804am lean pe SD w MAF.hplSD Tune Final SD w MAF w ltfts no fuel cutoffs.hpt0803pm sd only.hpl

2006 GTO 403ci. Car background was SD tune only with no MAF physically present prior to me owning the car. Few years back I installed a card style maf for NY compliance for NYS inspection, though typically always run it in SD only. Now...decided might's well tune the MAF in and use it. I was always reluctant since its an over the radiator intake, short run so MAF always looked erratic in various points of the curve but...anyway.

Problem: VE takes a dive forcing PE lean until ~3600 when maf takes over, and VE magically comes back to reality. Picture included.

Running SD only there is no issue.
Running MAF only there is no issue.

Turn the Maf back on and this problem presents. I moved MAF enable down, the problem moves with it. But this i believe is just masking the problem allowing maf to come into play. As of right now moved my MAF enable to 2200 and all seems well and goes into PE fine. But....does not solve the riddle. I'm stumped.

Anyone have any thoughts? I would figure someone has seen this. Had HPT take a look and they state the program is doing as it should. Almost like some sort of VE correction factor since, it commands PE right away but SD goes out to lunch. Thanks to all in advance!

[LS ROB]

not sure what the problem is but you will want to make the 5800 HZ cells the same on your high & low MAF Frequency tables.

[Stroked06Goat]

not sure what the problem is but you will want to make the 5800 HZ cells the same on your high & low MAF Frequency tables.

Good eye missed that. Must got touched on accident at some point.

[eXo3901]

This is odd and outside of what I would expect to see. It looks like fueling did not actually kick in until 3,600rpm, never saw that before. You cross 5,800hz on the MAF curve right when it all starts so could be a contributing factor. OTR intake isn't helping anything. You are logging VE airflow and MAF airflow at the same time, could be an issue. Try logging just one of MAF or VE airflow, not both.

I know it has been discussed and proven to not effect anything, but maybe raise your "VE maximum" table under the dynamic tab. Use the tune from the 804am lean pe log you posted and change nothing else but just copy your 105kpa VE column straight into the VE max table and multiply it by 5%. You do not have to do this, it's more for me to see if it does anything. I suspect it wont, but this is a specific scenario that I am not smart enough to think of anything else to try, tune wise.

[GHuggins]

I don't have a clue on your problem especially with it moving with the rpm setting, but I have done this for some NYer's - just run MAF only with all the codes set to not report so it passes all of the self test the day of or before the inspection. It's old enough, so you're allowed 1 not currently run test. Then run a SD setup the rest of the year unless you just want the MAF for a particular reason.

[Stroked06Goat]

I don't have a clue on your problem especially with it moving with the rpm setting, but I have done this for some NYer's - just run MAF only with all the codes set to not report so it passes all of the self test the day of or before the inspection. It's old enough, so you're allowed 1 not currently run test. Then run a SD setup the rest of the year unless you just want the MAF for a particular reason.

I will try these suggestions and report back. I appreciate the thoughts and maybe one of these is skewing the VE for some odd reason during its calculation. It is definitely making us scratch our heads. I mean logging the data (both MAF and VE) i havent noticed ill affects, though i know i've read about some who do. Thank You

I have typically done as you said for NYSI til now which is fine (the switch) and correct we're allowed to have one incomplete sensor test is fine soon as I load it it passes right away. And well I do actually like MAF data so its more of a 'want'. My SD at idle was having some issues with which when enabling maf solves, especially on startup. So i may simply need dig deeper into my idle cells and startup data in SD. Startup goes lean in SD ~15-16afr, where as MAF enabled keeps it in line as commanded in the 13's. Car not run in winter so not worried about that, more so just a nice fat startup is nice until warmed up.

[sgod1100]

Not saying it's going to solve your problem but try zeroing out ALL of your prediction coefficients under airflow>dynamic. I know with my ctsv these were causing a lean condition prior to going into "maf only" mode. Zeroed them out and fueling went straight to commanded

[Proxses]

Raise the VE Maximum table under dynamic airflow. It's 20+% lower than you're GMVE values.

[Stroked06Goat]

Raise the VE Maximum table under dynamic airflow. It's 20+% lower than you're GMVE values.

Heading out momentarily to give these suggestions a try. Will report back. Thanks all

[Stroked06Goat]

Reporting back. Confirmed that VE max was limiting the VE forcing it lean. Upped those by 25% and no issues after. Good call everyone and thank you.

All i can figure is if dynamic calcs are running, that VE max table isnt used and it goes straight to VE regardless. Makes sense why in SD i never had an issue. Thanks!

[Alvin]

Just a heads up.. depending on the cam and reversion this might not ever drive as good as it did when it was SD only.

[eXo3901]

Reporting back. Confirmed that VE max was limiting the VE forcing it lean. Upped those by 25% and no issues after. Good call everyone and thank you.

All i can figure is if dynamic calcs are running, that VE max table isnt used and it goes straight to VE regardless. Makes sense why in SD i never had an issue. Thanks!

Interesting to see that the table actually does influence operation while using the factory blended MAF/VE stuff. Thanks for testing that.

[Stroked06Goat]

Just a heads up.. depending on the cam and reversion this might not ever drive as good as it did when it was SD only.

You know this was my exact thought. Hence why I tuned my maf but had it off the past year, i found it to be erratic in some instances in that short run intake. But after putting 100 or so miles on it...it drives as smooth as it ever has. Cam is a Lunati custom grind 236/242 .612/.612 113lsa. So since its working alright I will run it a bit and see if it gives me any troubles. So far so good though. Pleasantly surprised at the results.