VE Drops to Zero Randomly

[SJ90]

Hello,

I recently started tuning SD on my car and I've started getting these bucks due to the car thinking the VE is 0 for a split second. It seems to take a bit of a drive after flashing a tune before they show up, but once they start, they are there every drive until I re-flash the car. Is this something anyone has heard of?

Back story on the car: It is a 2013 Cadillac CTS Wagon. I bought a wrecked CTS-V 6-Speed and all the harnesses needed to swap pretty much every part from the wrecked V into the wagon. I decided to buy a new LS3 in place of the LSA, since the mileage was high on the LSA and didn't want the wonderful gas mileage that comes with the LSA (I know LS3's are not exactly fuel-efficient). It drives well, but these fits are very annoying and depending on the load can be a bit violent. I just switched to E85 and it's a smidge lean now, so the sensor might be a bit off.

As it sits right now:
LS3
TR-6060
E67 out of the CTS-V
Wiring harness modified to mate to the LS3
CTS-V MAF
CTS-V Air Intake Temp Sensor (Usually sits downstream of the supercharger) - Moved to the airbox
LS3 MAP
CTS-V Barometric Sensor - Not Installed
CTS-V MAP (that goes between the throttle body and the supercharger screws) - Not Installed

Hiccup happens at 4:12 in the 211020 Log and 3:34 in the 211024 Log

Thanks

[07GTS]

keep the maf populated even if ur not using it as it sometimes references it, i thing this is only on some, see if that fixes it

[hjtrbo]

As above and also add...
P101 set to MIL on first error
ECM 4006 & 4007, High count / low count set to 1

[Alvin]

Hello,

I recently started tuning SD on my car and I've started getting these bucks due to the car thinking the VE is 0 for a split second. It seems to take a bit of a drive after flashing a tune before they show up, but once they start, they are there every drive until I re-flash the car. Is this something anyone has heard of?

Back story on the car: It is a 2013 Cadillac CTS Wagon. I bought a wrecked CTS-V 6-Speed and all the harnesses needed to swap pretty much every part from the wrecked V into the wagon. I decided to buy a new LS3 in place of the LSA, since the mileage was high on the LSA and didn't want the wonderful gas mileage that comes with the LSA (I know LS3's are not exactly fuel-efficient). It drives well, but these fits are very annoying and depending on the load can be a bit violent. I just switched to E85 and it's a smidge lean now, so the sensor might be a bit off.

As it sits right now:
LS3
TR-6060
E67 out of the CTS-V
Wiring harness modified to mate to the LS3
CTS-V MAF
CTS-V Air Intake Temp Sensor (Usually sits downstream of the supercharger) - Moved to the airbox
LS3 MAP
CTS-V Barometric Sensor - Not Installed
CTS-V MAP (that goes between the throttle body and the supercharger screws) - Not Installed

Hiccup happens at 4:12 in the 211020 Log and 3:34 in the 211024 Log

Thanks

This has been a bug with VVE tuning for quite a while. Not all do it, in fact by far most don't. 2008's I think seem to be the worse for some reason. Some cars can go weeks between this little hiccup. Others it might happen every 30-45 minutes. If a 2 bar OS is available that will take care of it. I've seen the VE spike very high and 0. It's always like someone momentary kills the ignition.

I talked to bluecat (OG VVE calculator guy) several years ago about this and he was aware of it and looking for answers too. There was some speculation on if it was a zone boundary issue or just a spike in the calculated VVE but if you graph it ultra precise nothing stands out and it will still happen right in the middle of a zone. Recalculating the zone boundaries can seem to reduce the symptoms but not guaranteed. Like I said before some happen so infrequently it's hard to know if you have it fixed or not.

I would love to have a fix for it. Quite a few cars we do will flat out not drive well with a mix MAF tune.

[SJ90]

Okay, I'll give that a go today and let you know. Might take a day or so to know if it's gone.

I had set it up originally with the MAF table populated and P0101 set to Mil on first error, but the car wouldn't run for more than idle, then go into limp mode. Hopefully, ECM 4006&4007 set to 1 will fix that.

[SJ90]

This has been a bug with VVE tuning for quite a while. Not all do it, in fact by far most don't. 2008's I think seem to be the worse for some reason. Some cars can go weeks between this little hiccup. Others it might happen every 30-45 minutes. If a 2 bar OS is available that will take care of it. I've seen the VE spike very high and 0. It's always like someone momentary kills the ignition.

I talked to bluecat (OG VVE calculator guy) several years ago about this and he was aware of it and looking for answers too. There was some speculation on if it was a zone boundary issue or just a spike in the calculated VVE but if you graph it ultra precise nothing stands out and it will still happen right in the middle of a zone. Recalculating the zone boundaries can seem to reduce the symptoms but not guaranteed. Like I said before some happen so infrequently it's hard to know if you have it fixed or not.

I would love to have a fix for it. Quite a few cars we do will flat out not drive well with a mix MAF tune.

Mine seems to happen about every 30 seconds when in certain loads and RPMs. So it's not really something I can live with. I don't believe 2 bar OS is available for the boosted E67, unless I'm missing something. It doesn't so up in the OS window.

Funny you say that about the mix MAF/SD tune, so far mine has done even more crazy things while mixed. It seems low RPM and decel it is always leaner than either on their own. With DFCO and CFCO completely disabled, it also likes to go to like 17:1 on decel, but only some of the time. I chased my tail with that setup for a while.

[SJ90]

Alright, I made the changes to the MAF curve, DTC, and fail counts. The car ran fine and had no issues on the way to work. The way home, the hiccups came back. I felt three in a 30 min drive.

Looking at the log, I was only able to find 2, and to my surprise, the VE spikes are now the opposite. When the car bucked, the VE was around 5,000 vs the ~2,000 it was a split second before and after.

See 4:33:23 for hiccup

[Alvin]

Kinda of a long shot but try turning the "supercharger fitted" to off. I've seen people try to turn that on cars that get supercharger on OEM NA cars and it start doing this. This sounds like it was a swap vehicle? If so I'd start over with a NA OS. A Trailbazer SS OS might work. I'm pretty sure some of the late NA CTSV's used E67's too.

[SJ90]

Kinda of a long shot but try turning the "supercharger fitted" to off. I've seen people try to turn that on cars that get supercharger on OEM NA cars and it start doing this. This sounds like it was a swap vehicle? If so I'd start over with a NA OS. A Trailbazer SS OS might work. I'm pretty sure some of the late NA CTSV's used E67's too.

I just tried that, unfortunately, it's still there. The only reason I had that set to fitted is I'm logging my WB through the supercharger inlet pressure circuit.

Yep, it's a swap. How do you know what OS can be loaded onto a ECM? And if I do an OS swap, will I need to use credits to license again?

Thanks

[hjtrbo]

Tangent alert. If you can't get the bug sorted, you do have the option to run smokeshows simultaneous MAF VVE tuning method.

[SJ90]

I'll take a look at that.

Does anyone know the formula (or even just inputs) the ECU uses to calculate VE?

[JustinWhiteTuned]

is there a reason your running with the stft and ltft diabled?

[JustinWhiteTuned]

i am seeing a multitude of issues as well as mismatch segments from a proper OS. seems to be quite a bit of copy paste work here and i would bet thats part of this issue atleast.

is this not a 2012 CTS-V? why does it show a 1 bar map and incorrect IAT as well as many other issues if so? no blower?


LSA LSX Channels.Channels.xml use these channels to log and that will help identify the issue at hand as well

[SJ90]

is there a reason your running with the stft and ltft diabled?

I am tuning the VE using my wideband. I had tried with the STFT and LTFT, but ended up chasing my tail a bit at the start. It is close enough now I can probably switch back to using fuel trims.

i am seeing a multitude of issues as well as mismatch segments from a proper OS. seems to be quite a bit of copy paste work here and i would bet thats part of this issue atleast.

is this not a 2012 CTS-V? why does it show a 1 bar map and incorrect IAT as well as many other issues if so? no blower?

This is a 2013 CTS wagon that I swapped the majority of parts from a 2010 CTS-V Sedan on to. The body and dash harness are out of a 2012 CTS-V Wagon, so I've flashed all the modules using the VIN from that car using a Tech2. The engine is an LS3 with a TR-6060

And yes, I have done quite a bit of copy-paste from a 2012 Camaro. I've obviously misunderstood something about how this all works, I thought copying the tables just changed values, but you are seeing mismatch segments? The 1 BAR is due to the LS3 without a blower. The IAT I've had to scale to get reading correctly, but they are both stock CTS-V parts, so I'm not sure why they were off 7-9?C.

[JustinWhiteTuned]

which IAT from the CTSV are you using? in the maf or from the lid? because you changed scaling in both

[JustinWhiteTuned]

try these files and see if it helps

[JustinWhiteTuned]

211023 LS3 VE CL test.hpt211023 LS3 VE OL test.hpt

[SJ90]

which IAT from the CTSV are you using? in the maf or from the lid? because you changed scaling in both

I am using both, MAF is IAT2 and I moved the lid sensor to the airbox and it is IAT1. I thought only having IAT2 might have been causing issues when calculating MAT.

I took a look through the files and it looks like the torque model is reset to what an LSA would be. I had tried that to begin with and the car would only work in MAF. As soon as it went over to SD it would buck violently. Changing torque coeffeicents to what a LS3 was fixed that. I'll copy over the rest though and give it a go.

Thanks

[travisty75]

Sorry for dragging this back from the dead, but did the OP (SJ90) ever resolve the issue?

My truck is far more tame than your car, but I am having issues just as you were. MAF/RPM/Throttle Position/Spark all show correct, VE drops to zero and my fuel trims go crazy trying to compensate, and .11 seconds later it's back to reading correctly.

[SJ90]

Sorry for dragging this back from the dead, but did the OP (SJ90) ever resolve the issue?

My truck is far more tame than your car, but I am having issues just as you were. MAF/RPM/Throttle Position/Spark all show correct, VE drops to zero and my fuel trims go crazy trying to compensate, and .11 seconds later it's back to reading correctly.

I never figured out what caused it, but when I returned to MAF/SD combined it went away. I see the odd spike in VE when I log still, but with MAF enabled it doesn't cause any break in power now.