[NickeyMatt1LE]

Comparing cylinder airmass from car to car is apples to oranges unless both logs are at the same atmospheric pressure and temp. In the midwest at around 2000 da I'll see high .8's maybe touching .9 on a stock lt1. Full bolt ons .96-.97.

Gm's calibrations are not entirely generated by a human. They take data from dyno cell testing and real world driving and plug it into another program that compiles it and spits out code for calibrations. That's why some of the tables have skewed areas. Drivability is of a lesser concern that passing emissions and fuel economy standards.

[gtfoxy]

Originally Posted by cmitchell17

What do you mean? I really can't understand why GM went through the trouble of calibrating and certifying 2 and more LT1 tunes one for Corvette and one for Camaro, I understand they have 2 different manifolds which necessitates 2 different tunes for the different O2 feedback parameters due to the different locations of the O2s on the different manifolds. But why did they go through all the trouble of having a unique Corvette timing table? I am pretty sure both cars meet the same emissions standards and have the same equipment besides the manifolds, especially given how GM is so good at "cutting costs".

It drives me insane to see all the inconsistency in the stock GM tables, I don't know if we could ever get to the bottom of why unless we could actually ask the calibration engineer who did it. I have a feeling they are not using a nice GUI interface like we have with HP Tuners and EFI Live and they may even have to handoff parameters they choose over to a software engineer who then complies the code and maybe stuff gets lost in translation?

I don’t know man, I just remember a guy posting a few years back on ls1tech stock VE, MAF transfer & a few others from a Stock 05/06 vette & a GTO & they were way different. The GTO’s high end VE looked like a 2yr old mapped it.

Add: IIRC the MAF table had more data points, but similar curve.

[KingLT1]

Originally Posted by NickeyMatt1LE

Comparing cylinder airmass from car to car is apples to oranges unless both logs are at the same atmospheric pressure and temp. In the midwest at around 2000 da I'll see high .8's maybe touching .9 on a stock lt1. Full bolt ons .96-.97.

Gm's calibrations are not entirely generated by a human. They take data from dyno cell testing and real world driving and plug it into another program that compiles it and spits out code for calibrations. That's why some of the tables have skewed areas. Drivability is of a lesser concern that passing emissions and fuel economy standards.

[cmitchell17]

Originally Posted by NickeyMatt1LE

Comparing cylinder airmass from car to car is apples to oranges unless both logs are at the same atmospheric pressure and temp. In the midwest at around 2000 da I'll see high .8's maybe touching .9 on a stock lt1. Full bolt ons .96-.97.

Gm's calibrations are not entirely generated by a human. They take data from dyno cell testing and real world driving and plug it into another program that compiles it and spits out code for calibrations. That's why some of the tables have skewed areas. Drivability is of a lesser concern that passing emissions and fuel economy standards.

I get what you are saying, and people compare dyno runs, and un corrected dyno runs too, between different atmospheric conditions. I still think we can use the air density torque multiplier PID to "correct" the air mass, although it may need to be inversed since its seems reversed so it would have to be divided instead of multiplied.

I would be very surprised if GM released a calibration for production without at least one human looking at it, my guess is some of the tables may have never even been actually graphed in a GUI before (expect besides us) for anyone ever to notice how discontinuous they look. I still think they care about drivability, but makes sense that they don't given how many weird and "wrong" things we see in the calibrations.

[cmitchell17]

Also no one from Solo performance is answering, is there anywhere else I can get a primary cat delete pipe? I checked ebay also.

[6spdhyperblue]

If there’s one thing for sure, theres a ton of assumptions left to us when reverse engineering the calibrations, It’s not easy.

so when we look at the compare of the lt376 vs the base vette we don’t know if they are changing tables we can’t see. The biggest one is the PE, yes the stoic setting is different, but the lambda is .92 if you weigh in the stoic difference, which I must think about more. I’m not sure if that matters, if not, it’s even leaner. What’s that about? The lt376 is non emissions compliant and is mostly targeted to historic plate connect and drive vehicles which will give it lower emissions with this motor than the sloppy Holley Dominator sitting on the motor they took out. Finally a gateway into to seeing their no compromise lab tested PE lambda, right??? Nope, we get a total wtf moment.

Can you even run these motors that lean? Has anyone run .93 at the top of the curve? On e0? It’s MAF only right? Or is it 1999 and are they @$$!ing the PE table? Would they stoop so low?

[cmitchell17]

Originally Posted by 6spdhyperblue

If there’s one thing for sure, theres a ton of assumptions left to us when reverse engineering the calibrations, plus we are using totally different tools and views than them. It’s not easy. we don’t see all the tables too.
Hence the ‘change as little as possible‘ shift on hpt forum.

so when we look at the compare of the lt376 vs the base vette we don’t know if they are changing tables we can’t see. The biggest one is the PE, yes the stoic setting is different, but the lambda is .92 if you weigh in the stoic difference, which I must think about more. I’m not sure if that matters, if not, it’s even leaner. What’s that about? The lt376 is non emissions compliant and is mostly targeted to historic plate connect and drive vehicles which would give it lower emissions with this motor than the sloppy Holley Dominator sitting on the motor they took out. Gateway to seeing their no compromise lab tested PE lambda, right??? But we get a total wtf moment.

Can you even run these motors that lean? Has anyone run .93 at the top of the curve? On e0?

Yes it's completely contradictory information. We know that to pass emissions they are going to target as close to stoich as they can but even more important than that concern is to ensure it meets the one month long WOT run, usually this is more of a problem at high rpms so we see factory PE in a "safe" range but at idle and low rpms we see it at basically stoich since burning a piston is way more likely running WOT for a month at 6000 rpms vs 1000 rpms. And go over step more with truck and non performance engines we see calibrations that don't even go into PE mode for over a minute at WOT (sometimes they have a around 5000rpm bypass).

But maybe . 92 lambda is where they found peak power? I don't think we can discount it as a fluke or error or even laziness/beaurcacy at GM. You would think they would have tried to make the most power possible given they were no longer constrained by emissions and probably durability too.

[Trochoidal]

Originally Posted by cmitchell17

Also no one from Solo performance is answering, is there anywhere else I can get a primary cat delete pipe? I checked ebay also.

How about New Era Performance?!

[cmitchell17]

Originally Posted by Trochoidal

How about New Era Performance?!

I want to keep my secondary cat and hopefully keep the unburnt fuel smell down and everyone says deleting the cats makes it sound bad and raspy. I think New Era only makes a pipe that deletes both cats.

[cmitchell17]

Originally Posted by 6spdhyperblue

If there’s one thing for sure, theres a ton of assumptions left to us when reverse engineering the calibrations, It’s not easy.

so when we look at the compare of the lt376 vs the base vette we don’t know if they are changing tables we can’t see. The biggest one is the PE, yes the stoic setting is different, but the lambda is .92 if you weigh in the stoic difference, which I must think about more. I’m not sure if that matters, if not, it’s even leaner. What’s that about? The lt376 is non emissions compliant and is mostly targeted to historic plate connect and drive vehicles which will give it lower emissions with this motor than the sloppy Holley Dominator sitting on the motor they took out. Finally a gateway into to seeing their no compromise lab tested PE lambda, right??? Nope, we get a total wtf moment.

Can you even run these motors that lean? Has anyone run .93 at the top of the curve? On e0? It’s MAF only right? Or is it 1999 and are they @$$!ing the PE table? Would they stoop so low?

I also noticed with the GMPP timing table on my tune I believe it's pushing the timing so high that it's sensing it's making too much torque and pulling timing back, so it ends up oscillating back and forth between 42 and about 16 degrees of timing on the interstate, it looks like a square wave. When it pulls timing I can see the immediate torque source go from "none" to "axle"

I have never really been able to fully understand how the gen V torque based stuff works, but I believe the proper way to fix this would be to demand more torque from the driver demand table. Since the GMPP tune uses the same virtual torque table I don't think virtual torque should be altered, a lot of people don't agree but I put my trust in the virtual torque mapping by GM and believe it represents a accurate amount of torque that the Gen V combustion system will make with a certain airflow and timing.

I think an even more proper way to fix this is to change the tables that control the relationship between the airmass/airflow and throttle blade opening, there is the chicken egg condrum somewhere in here but we don't have access to those tables.

That brings me the though of trying to fill flash the whole GMPP tune into my car? Problem would be the driver demand tables are set up for engine torque and my (2017) is setup for axle torque so not sure if this will cause problems?

Better thing to probably try first is to try to translate the GMPP diver demand table increase over to my tune.

[gtfoxy]

Originally Posted by cmitchell17

Yes it's completely contradictory information. We know that to pass emissions they are going to target as close to stoich as they can but even more important than that concern is to ensure it meets the one month long WOT run, usually this is more of a problem at high rpms so we see factory PE in a "safe" range but at idle and low rpms we see it at basically stoich since burning a piston is way more likely running WOT for a month at 6000 rpms vs 1000 rpms. And go over step more with truck and non performance engines we see calibrations that don't even go into PE mode for over a minute at WOT (sometimes they have a around 5000rpm bypass).

But maybe . 92 lambda is where they found peak power? I don't think we can discount it as a fluke or error or even laziness/beaurcacy at GM. You would think they would have tried to make the most power possible given they were no longer constrained by emissions and probably durability too.

Don’t get hung up on PE tables or Lambda.

The reality of what those can be is found in EGT, BSFC, gas mix ratios & knock.

That reality is, & I’m not saying it is, you should not need a PE at all. An ICE should be able to be ran at stoich or near stoich regardless of engine load.

[6spdhyperblue]

Originally Posted by cmitchell17

I also noticed with the GMPP timing table on my tune I believe it's pushing the timing so high that it's sensing it's making too much torque and pulling timing back, so it ends up oscillating back and forth between 42 and about 16 degrees of timing on the interstate, it looks like a square wave. When it pulls timing I can see the immediate torque source go from "none" to "axle"

I have never really been able to fully understand how the gen V torque based stuff works, but I believe the proper way to fix this would be to demand more torque from the driver demand table. Since the GMPP tune uses the same virtual torque table I don't think virtual torque should be altered, a lot of people don't agree but I put my trust in the virtual torque mapping by GM and believe it represents a accurate amount of torque that the Gen V combustion system will make with a certain airflow and timing.

I think an even more proper way to fix this is to change the tables that control the relationship between the airmass/airflow and throttle blade opening, there is the chicken egg condrum somewhere in here but we don't have access to those tables.

That brings me the though of trying to fill flash the whole GMPP tune into my car? Problem would be the driver demand tables are set up for engine torque and my (2017) is setup for axle torque so not sure if this will cause problems?

Better thing to probably try first is to try to translate the GMPP diver demand table increase over to my tune.

The OS does not match and they say you should never load the tune that isn’t the original one from your car. If the OS matched you might be able to do a segment swap. The LAN in the car needs the vin and OS number from the ecm to operate is my understanding.

I think trying to get the DD table set up is a good next step.

[cmitchell17]

Originally Posted by gtfoxy

Don’t get hung up on PE tables or Lambda.

The reality of what those can be is found in EGT, BSFC, gas mix ratios & knock.

That reality is, & I’m not saying it is, you should not need a PE at all. An ICE should be able to be ran at stoich or near stoich regardless of engine load.

I agree, but stoich is the optimal tradeoff between emissions and fuel economy given you have a three way catalyst.

My understanding is that you enrich for more power since that extra little fuel you give it is just to ensure that you use up all your available oxygen in your charge before it goes out the exhaust, it would seem like this factor would be more important as rpm goes up, you would also think timing would be dependent upon rpm as well, needing more timing as rpm goes up, but I'm not sure that's the case looking at stock timing tables and from what I've read. Timing is more directly dependent on cylinder pressures.

[cmitchell17]

Originally Posted by 6spdhyperblue

The OS does not match and they say you should never load the tune that isn’t the original one from your car. If the OS matched you might be able to do a segment swap. The LAN in the car needs the vin and OS number from the ecm to operate is my understanding.

I think trying to get the DD table set up is a good next step.

I went back and compared it to the regular GMPP LT1 and its a lot simpler to understand now that the scales and stuff are the same between tunes.

Use this file to compare it to:GMPP LT1 Crate Engine Tune.zip

So you are right there aren't any "secrets" in the LT535 GMPP tune that makes a cam car run any better. Its funny that they did the same "hacks" as we do. For example, they changed the min timing advance tables to 14 degrees in the idle range im assuming in attempt to force it to idle with more timing. However, this messes up the torque based idle control and makes it unstable and rev up and down until the engine dies. The only way I have found to make it idle with more timing is slightly increase the virtual torque in the idle regions even though I really want to leave it stock. Unless there is something else going on in the background my car won't idle with the GMPP tables.

As for the driver demand, basically the last 2 rows is 86% and 100% throttle, they increased the 86% row, uniformly throughout VSS, by about 15% and the 100% row by 25%. There are slightly different numbers in the A vs B and C demand tables but I contribute this to rounding error. Which is funny to since this is how everyone else seems like they did it as well.

Like you were saying im not sure the slightly different numbers in the adaptive idle proportional control tables really mean much and maybe they "accidentally" got changed or something.

I haven't had a chance to run it on the highway again to see if the high GMPP timing table makes the immediate torque control kick in and reduce timing and cause the surge, I am assuming the same thing is going to happen.

As a side note does anyone else have trouble with getting the stock 8L90 torque converter to lock at WOT? The WOT lockup tables are completely ignored, and it reminds me of how the Duramax and Allison acted, there ended up being a limit table that would inhibit TCC lockup above a certain slip threshold at WOT, I believe the exact same thing here is happening that we need to uncover in the tune.

I've always wondered if it was safe to try to full flash a different OS, I know I have done it with older LS1 style PCMs with EFI Live but never with HP Tuners.