Procharged z06. Throttle Only ~60%

[Redline MS]

I was interested in this because I've seen more than enough scaled 6speed tunes that didn't have the airmass tables touched (in other words they were about 30 to 50 percent under what they should have been after scaling) that caused the transmissions to start slipping withen a few hundred miles - I would see these after other tuners had all ready done "their magic".... SO I was curious what scaling the airmass and EQ coefficients tables together in the same "under fashion" would do?

I think my own tunes speak for themselves in quality, so won't get into that one

Don't take my closing statement as a direct dig as that wasn't the intention. It just gets frustrating to lay out facts of how the controller works yet people want to start turning other knobs and make up theories...

I can't tell you how many calls I have taken since the 6 speed came out about hey can you help me with my trans.....I would ask how was the engine calibrated and they say "oh the engine runs great and it made great power"...just to find out it wasn't calibrated right and the trans torque was all messed up.....regardless....many don't want to put the effort in today to do it right.

the problem with the airmass tables is that they are also regression based coefficients so there values are not really based on a percentage. It isn't like adding 20 percent to a traditional VE surface and getting a 20 % change. A 20% change in a coefficient could be 2 or 20 % change at the end of the calculation. In short changing them does cause an effect but it also is messing other things up.

[GHuggins]

Don't take my closing statement as a direct dig as that wasn't the intention. It just gets frustrating to lay out facts of how the controller works yet people want to start turning other knobs and make up theories...

I can't tell you how many calls I have taken since the 6 speed came out about hey can you help me with my trans.....I would ask how was the engine calibrated and they say "oh the engine runs great and it made great power"...just to find out it wasn't calibrated right and the trans torque was all messed up.....regardless....many don't want to put the effort in today to do it right.

the problem with the airmass tables is that they are also regression based coefficients so there values are not really based on a percentage. It isn't like adding 20 percent to a traditional VE surface and getting a 20 % change. A 20% change in a coefficient could be 2 or 20 % change at the end of the calculation. In short changing them does cause an effect but it also is messing other things up.

This has honestly never occurred to me Howard... I guess if I had just thought about it, it makes perfect sense... All because the airmass tables are just a small part of the "actual" torque model - just like the "map" table is just one table for the VE table. I know the airmass tables control everything from spark, trans shifting and throttle controls, so admittedly I am guilty of using them to hit timing targets on really cammed motors at idle when nothing else in the tune would work..... I even still to this day increase them very, very small amounts (2-15%) just for trans hold pressures. Admittedly though, I have even started going away from this..... Sounds like my own findings and thoughts have been leading me in the right direction?

I guess I was just "too" curious of the effects of changing the EQ and airmass tables in unison - especially making them lower values as a whole?

[Redline MS]

This has honestly never occurred to me Howard... I guess if I had just thought about it, it makes perfect sense... All because the airmass tables are just a small part of the "actual" torque model - just like the "map" table is just one table for the VE table. I know the airmass tables control everything from spark, trans shifting and throttle controls, so admittedly I am guilty of using them to hit timing targets on really cammed motors at idle when nothing else in the tune would work..... I even still to this day increase them very, very small amounts (2-15%) just for trans hold pressures. Admittedly though, I have even started going away from this..... Sounds like my own findings and thoughts have been leading me in the right direction?

I guess I was just "too" curious of the effects of changing the EQ and airmass tables in unison - especially making them lower values as a whole?

Trust me we all have to play "black magic" calibrating at times as we really don't have the tools nor all the parameters we need to do it right. Its frustrating at times to have too much information as you realize how limited we really are. However knowing how it works "exactly" makes you smarter in reasoning through what we do have access to.

When you step back and go back to the early days of Speed Density based system ( in the days when torque control wasn't even in the game); the VE surface was a map of the airflow through the engine (as it is still today), If we where to attach an electric motor to an engine on a stand and start sucking air through it we could essentially create a VE map....its all about airflow....once the airflow is correctly mapped when can then calculate fuel mass to match it.....another topic! It happens to be that airflow and torque have a direct correlation. Since these modern day cars now use "torque" to control many functions, such as throttle, boost control and traction control systems if we do not go back to the root function it all pours down hill...

GM cars happen to use two models. One is MAF based and one is MAP. Both have there leading role but both intertwine. The thought of lowering your high speed enable to low number and thinking your going to MAF tune the car like a Ford is not going to get the job done. Unfortunately the harder air model is the MAP. Much in part to the coefficient conversion process. All we can do is use the tools and get it close......but it needs to be done....

HT

[04blackgmc]

I would not agree more. For now really there is no EXACT science behind the new stuff and everyone is just trying to "get by".

[Nick@Newtech]

Caught this thread and it was a great read. I am currently working on a C7Z with a cam, LTs, upper and lower pulleys, I have corrected the throttle blade issues that the previous tuner did not address via driver demand tables, what I am experiencing now is a nasty TQ management timing dip around 52-5500(logged), the car no matter what I try it drops 2-5 degrees right in this rpm range. I have gone through the entire tune looking for any kind of limiters that may be causing this? really want to fix this issue for my customer. car only makes 650/650 with a nasty dip in the mid range. I plan on trying to get some more logging done with TQ output, is the pcm hard coded to 889 calculated?

Nick

[memphiss13]

Caught this thread and it was a great read. I am currently working on a C7Z with a cam, LTs, upper and lower pulleys, I have corrected the throttle blade issues that the previous tuner did not address via driver demand tables, what I am experiencing now is a nasty TQ management timing dip around 52-5500(logged), the car no matter what I try it drops 2-5 degrees right in this rpm range. I have gone through the entire tune looking for any kind of limiters that may be causing this? really want to fix this issue for my customer. car only makes 650/650 with a nasty dip in the mid range. I plan on trying to get some more logging done with TQ output, is the pcm hard coded to 889 calculated?

Nick

I know this is an old thread, but did you ever figure out what caused this? Or has anyone else encountered this? I'm working on a 15 C7Z M7 with an F1X and I'm having the exact same issue. Anywhere from 5-7* of tq mgmt retard. I made adjustments to the airmass tables (around 30% reduction) which made a lot of difference and got it down to only 1 deg of retard. Then I got more aggressive with the timing, made more power and the issue came right back.

I'm thinking the issue is in my VVE, but I can't get the car to go full throttle when I fail the maf so I've only been able to tune the part throttle areas of the ve table. I really don't like to hack things and I feel that adjusting the airmass tables to get around this is just going in the wrong direction.

[Ben Charles]

Must be Randys car.....

You can tune the VVE no problem on the 14-15 cars
Put the airmass tables back to stock, that will help.

[memphiss13]

Yeah the airmass tables were stock when I attempted to run it with the maf failed. It would only give me about 40% throttle though. I didn't expect to have a problem running sd on a 15, but its there so I guess I'll have to figure it out.

[GHuggins]

[2320.71]*(273.15+[50011.241])*1000*15/([50070.56]*[50030.91])

Calculated GMVE - it's not in the formula but you need to multiply it by an air fuel error too... Either that or have the MAF very very close - should calculate out better that way right off the getgo... There's a whole listing of these on the gen 4 forum somewhere - no need to kill the MAF to tune the VE table...

[memphiss13]

Thanks GHuggins. I'll give this method a shot. I ran across that thread a while back and found it interesting, but I never had a reason to try it since the old methods hadn't ever failed me. Looks like now is the time to use it. I don't mind taking the extra time in order to avoid short cuts and trickery whenever possible. I'll be sure to come back and let you guys know how it turns out.

[99LS1SS]

I hate to ask stupid questions but what does DD mean? I've looked for the past 30 minutes and haven't been able to find out what it means.

[Ben Charles]

Driver demand
The tq logic starts here...

[TSloper]

[2320.71]*(273.15+[50011.241])*1000*15/([50070.56]*[50030.91])

Calculated GMVE - it's not in the formula but you need to multiply it by an air fuel error too... Either that or have the MAF very very close - should calculate out better that way right off the getgo... There's a whole listing of these on the gen 4 forum somewhere - no need to kill the MAF to tune the VE table...

I've been working in Matlab to see if we can get to a tool set that will modify the coefficients correctly. As already stated the MAP side is the pain in the ass part.

[GHuggins]

If you can come up with something that works good, then sign me up The formulas work, but I think your better off having several of them average out together which seems to always bog the scanner down or freeze the scanner up... Of course you could chase your tail on fueling forever if you really wanted to nick pick one or two percent... The biggest reason for tail chasing is the injector offset table - it's amazing how much injector tip temperature changes your fueling - it alone can change it 10% - AND NO you can't just zero it out... There is a formula and a correct way to do it, but I can't post it nor give it out... That's up to the man that came up with it...

I find it most easiest to dial in the VE only after dialing in the MAF and injector temp offsets and then I'll revisit the MAF again after words... BUT that's me...

If the coefficient tool wouldn't throw out all of your hard gotten data when it created coefficients it wouldn't be half bad, but seems like you have to play with it a lot to keep it "how it needs to be" even if you change the boundary settings which I personally don't touch anymore...

Edit: Forgot injector temp offset doesn't apply to gen 5's - other than that - same process...