Sudden increase in Air/Cyl

[Mileage]

We tried Swingtan's VVE dial in guide on our E67 boosted application. The parameters seemed to match the E38 very closely. We experienced very rich conditions at part throttle operation over about 90map. Idle and light throttle was okay as well as WOT but it would go rich at moderate throttle either on the way up or down. It stayed rich as I held the throttle constant for several seconds, ruling out a transition issue. We noticed tha Air/cyl jumped, therefore commanding more fuel. The theoretical air/cyl is about 67 non-boosted, 100 at 150 map. If I can attach the dashpage you can see it jumps much higher (160) as I let off after a WOT blast and shift and blast.

Any suggestions as to what goes into the air/cyl calculations or what to look for? Thanks

[GMPX]

In the coefficients tables, is the last column all zero's?

[Mileage]

I will check tonight.

[rhit_rs]

Mileage checked tonight and the last column (MAPSq) is all zeros.

[scdyne]

Can you post an image of your VVE?
At around 4200 RPM you go from one MAP zone to another and if you haven't massaged them much from stock then you might be in an area that is a continuation of a calculation that originally stopped at 87kpa.

Did you remove the MAF or just disable it? I found that other than initial start-up I had success just disabling it and not physically removing it from the system.

I assumed that the IAT needed to be calculated at that point still and left it in. The problem is that I didn't spend enough time looking at weather it was 100% right because it worked for me.

Having relocated the throttle body to the other side of the engine and the MAF for that matter how clean is your MAF calibration?

Also does the supercharger bypass valve open and close like it's supposed to or is it always closed right now?

[rhit_rs]

I'll have to leave the posting of the VVE table up to Mileage, but it's not much different than before we tried disabling the MAF (at bit more fuel under boost at high rpm). We followed Swingtan's guide to VVE tuning and disabled the MAF as well as unplugged it. The engine will run well at WOT once it gets through the sudden change in Air/Cyl.

The IAT is in the LSJ intake manfold and separate from the MAF sensor.

We are planning to use the VVE table to calibrate our MAF. We changed it some to correct for the tubing size prior to adding the supercharger, but we have not adjusted it since.

The bypass valve is opening and closing as it should.

[Mileage]

Adam,
It looks like rhit rs has answered your questions. I can post the VVE image tomorrow but I enlarged it and looked it over carefully last night. No irregularities in the area where we are going rich. Values are well below WOT areas. Nice smooth surface.
Do you know where GMPX was going with the question about the zeros in the last column of the table?
Thanks for the help.

[GMPX]

EFILive automatically fixes the MAP_SQ column to zero, without that done you can get some very weird airflow values calculated, it's a bug in GM's ECM code.

Cheers,
Ross

[Mileage]

Here is the VVE graph as requested. The air per cylinder in the dashpage above tells the story. It goes way up at part throttle both on speed up and slow down.
To recap, we had been driving the car with the MAF connected and it ran good albeit a little rich for safety. It seemed to be getting a couple of hickups that got worse as time progressed so we decided to follow Swingtan's guide and tune MAFless also making sure that the fuel trims were inactive. Light throttle and WOT were okay but moderate throttle was very rich, missing with black smoke. I have searched the forum some. We had added "one" to the calibration values early on. I did not see any other hints of the problem. Thanks for the help.

[rhit_rs]

The attached log file clearly shows the problem Mileage and I are having. Any ideas on what is causing this?

[scdyne]

Sorry I haven't had time to try and duplicate this with my set-up. I did however go back and look at all of my log files and have never seen this with my configuration.

What do the Throttle VE tables look like? Any chance you are meeting the conditions to have that effect the overall VE?

[Highlander]

You know.... Weird as it may seem... Do you have a different map sensor to try out?

[scdyne]

Actually what is the part number for the MAP sensor you are using?
I'm wondering if possibly you are using a 1 bar map sensor still; when it goes beyond 105 kPa it shorts, but as you come back into a measurable range it functions as intended. That would be close to maximum voltage of the sensor and be just like you were still pushing big pressure.

[rhit_rs]

The MAP sensor is from the stock LSJ engine that we took the intake manifold and supercharger from. The datalog of the MAP sensor looks reasonable, but we did notice the spike in grams/cyl (and pulse width) happens right around 90-100kpa. Mileage is going to look at the Throttle VE table tonight.

[Mileage]

I looked at B8048, Throttle VE Enable, it is set at 75%. Maybe our VVE table is all out of whack but we go into Throttle VE at WOT and it clears it up.
I was not aware that there was Throttle VE Mode or how to tune it. EFI Live has limited descriptions associated with the values in that area. I will look at the logs to see if anything is happening at 75% throttle. Thanks Adam.

[Mileage]

I tried setting B8048 (Throttle position to enable Throttle VE) to 60% and it did not seem to change much. I will try setting it high (150% or so) tonight to see if the A/F stays way rich at WOT

[Mileage]

I eliminated the Throttle VE by setting it to over 100% and the Air/cyl stayed high! Thanks Adam. Basically then our VVE figures were all out whack. I lowered the upper ones 50% linnerly down to no change near the NA range and it ran okay. A little tweaking and it runs good, 14ish AFR's at cruise and 12.5ish under power.
My wife has a track day midweek and I am running out of tuning time. Will it hurt anything to just leave all the tuning settings from Swingtan's guide set and drive it until I have time to finish tuning? I noticed her timing advance is a little low but it is based on air/cyl so until I get the VVE close, which is evidently used to calculate air/cyl, I do not want to take the time to optimize timing.
I tried to search a little for Throttle VE but VE is too short and just Throttle brings up too much. Much of the tunning help is on the E38 and I do not know if they have Throttle VE, but if someone could put a note to turn ThrottleVE off as well as the MAF, it might save others some head scratching.
Thanks to everyone for the help. The learning curve is steep for this old guy. I did learn a little about EFI Live's map feature, enough to map the AFR's so I could put Scan and Tune side by side for changing VVE values. Good work guys. Next I will try to figure out how to use them more automatically but I was hesitant when the columns and rows did not match. Later,
Ken

[gmh308]

EFILive automatically fixes the MAP_SQ column to zero, without that done you can get some very weird airflow values calculated, it's a bug in GM's ECM code.

Cheers,
Ross

That's an interesting one Ross. With the MAP_SQ column with zeroes I get some wierd airflow values.......when MAP crosses the 60kpa line, airflow doubles in 100ms, which sends timing and torque signals on a loop &= surge.

Maybe their not completely related, yet to get to any exhaustive checking :shock:

[hymey]

Have you guys tried adding 1 to the whole VVE table. I have had some weird things happen and doing this fixed the issue also seamed to make it easier to make minor changes to the vve..

With the throttle VE. Interesting I have never been able to make it work. Also note the alpha n ve table is set to 0 so realistically it will go lean.

Your vve looks very steep. I noticed it exceeds 4000. What kind of FI do you have? What size injectors?

I use a STFT BEN pid to do 0-80kpa using the short term fuel trims. I hit as many cells as possible driving for around 20 minutes(only need to do this once) then paste and multiply that's low map done. Trims should be pretty close to perfect. Then I basically use swingtan's guide in a 2 bar application. From 80kpa upwards I copy the ben's from the log and paste and multiply then build the high side of the vve so all numbers are close to the ones corrected and basically the vve is within a few % up top and only needs some slight touching up to get within a couple of % of commanded(that's the fun bit:))

After that I plugged in my MAF and scaled it. My commanded afrs read actual now from the w/b and no drift. Fuel dynamics functions correctly and you do not have to fudge it to work right like you do with SD tuning in e38s. Plus airflow correction works correctly with the MAF aswell.

[Mileage]

hymey,
That was our old VVE that was giving us trouble when we turned off the MAF. It was waaaay high. New top values are about half that. Ken

[gmh308]

hymey,
That was our old VVE that was giving us trouble when we turned off the MAF. It was waaaay high. New top values are about half that. Ken

What changed that enabled the top VVE values to be about half of those shown in posted image?

:)

[Mileage]

gmh308,
When we bolted on the blower we did not know to disable MAF before tuning the VVE table. We just extended the 1 bar map on up into the 2 bar range, and with a little tweaking it ran okay for track day use. (That is where the high VVE values came from. It must have been running mostly on MAF in the higher rpm ranges.) By the end of the day it had a couple hickups so we thought LTFT or STFT might be messing us up and we decided to do it right and use Swingtan's tuning guide to disable fuel trims and MAF. That is when it started running way rich at moderate throttle but okay at light throttle and WOT. Light throttle was okay from the factory part of the VVE and WOT was okay due to Throttle VE taking over. does this explain it? Is it okay to drive it this way, with fuel trims, MAF, and Throttle VE disabled?

[gmh308]

gmh308,
When we bolted on the blower we did not know to disable MAF before tuning the VVE table. We just extended the 1 bar map on up into the 2 bar range, and with a little tweaking it ran okay for track day use. (That is where the high VVE values came from. It must have been running mostly on MAF in the higher rpm ranges.) By the end of the day it had a couple hickups so we thought LTFT or STFT might be messing us up and we decided to do it right and use Swingtan's tuning guide to disable fuel trims and MAF. That is when it started running way rich at moderate throttle but okay at light throttle and WOT. Light throttle was okay from the factory part of the VVE and WOT was okay due to Throttle VE taking over. does this explain it? Is it okay to drive it this way, with fuel trims, MAF, and Throttle VE disabled?

Ok! Got it now thankyou! :) What did you need to do to get Throttle VE to play a part?

[hymey]

whats ur 2 bar parameters. Should be 188.00 at b2101, 2103 should be 10, and change b2105 to FAST. disable your LTFT permanantly. Is not required.

[hymey]

One more thing. I have not personally tested this, but a well known tuner in QLD sets B8024 and 025 to 8000rpm. I have never had to do this to go soley SD. Just unplug maf and turn off the mil light. But he had issues with the vve and doing this procedure fiixed it in his belief. Again I don not know this for sure as I have never had issues with g/cyl values going haywire but is worth a try.

[Mileage]

gmh308, The Throttle VE was already active above 75% throttle opening. I changed it to "above 110%" to eliminate it.
hymey, Thanks, I will check those parameters. Ken

[gmh308]

gmh308, The Throttle VE was already active above 75% throttle opening. I changed it to "above 110%" to eliminate it.
hymey, Thanks, I will check those parameters. Ken

Thanks Ken, It came from the factory like that?

Cheers, Ian

[Mileage]

Yes, 2007 Solstice, 5 speed, base model.

[gmh308]

Yes, 2007 Solstice, 5 speed, base model.

Ok thanks Ken. Any chance you could post a stock tune up?

Cheers, Ian

[Mileage]

Sure. Give me a couple days. Track day tomorrow with prep tonight and I do not have usable internet access from home. I think there is a place to post tunes. I will note here when posted. I'll post the modified tune when sorted out better. Ken

[hymey]

yeah keen to see that. I haven't been able to get alpha n to activate with my operating system. Its set at 100% throttle and the tables all have 0 in them.

[Mileage]

Due to calibration or other issues my ecm thinks my throttle is only opening 88%, thus the 75% enable still activated Throttle VE. You might check your and lower it a few percent. Good luck with it.

[rhit_rs]

Sure. Give me a couple days. Track day tomorrow with prep tonight and I do not have usable internet access from home. I think there is a place to post tunes. I will note here when posted. I'll post the modified tune when sorted out better. Ken

I'll post up the stock tune this evening. I have a bit more free time than Mileage, since I'm stuck in an apartment in a city and all.

Mileage, are you going to put a little timing back in it?

[Mileage]

rhit, Yes I will put some timing in tonight. I am learning to use the "MAP" tab on EFI Live scan tool. It seems like I have to fiddle with it to get it to work but anyway, it works providing good tabular data, and the timing did not look bad except a little low at 4500-5500 rpm and over about .95 calculated air/cyl. When we were running MAF the air/cyl was probably assumed lower and kept the timing up there.

[rhit_rs]

I've attached the stock tune. Use at your own discretion.

Josh

[gmh308]

I've attached the stock tune. Use at your own discretion.

Josh

Thankyou! Interesting how the Throttle VE is used. Seems to play a major role in the Solstice.

Cheers, Ian