2014 Corvette Stingray Stock Tune VS ProCharger's Tune (comparison)

Hi all,

I had the fortunate opportunity to install a ProCharger kit on a new 2014 Corvette Stingray. Having experience working on all model Corvettes, I am happy to say the C7 is by far the easiest model to work with yet. Everything is simple yet sophisticated, it was a very straightforward process. I have attached both the stock tune file and ProCharger's tune file for anyone who is interested in dissecting the E92 controller/tune. I have some questions based on what I am seeing in comparing the files:

Attachment 16756
Attachment 16757

1.) It appears as if the VVE tables have remained unchanged and the supercharger option has not been selected. What is this engine controller looking at to determine it's fueling?

2.) The MAF table was scaled back, a lot... Wouldn't the added air being forced into the engine mean the MAF should be scaled higher?

3.) The AFR was leaned out to 12.7, being forced induction, isn't this too lean? Maybe the direct injection system calls for a leaner AFR.

4.) What exactly is "commanded power mode, A, B, and C"?


That's all, feel free to discuss!

Thanks

1: If it's using the MAF, it won't use the VVE under boost conditions.
2: and 3: It all depends on what the exhaust AFR is. Commanding specific ratios does not actually mean that's what the engine is using. Stick a wideband in the exhaust and see what the engine is really using.
3: Command torque is the way of the future. The ECM maps the pedal position to a "desired torque" value. Then it uses the torque estimation tables to work out how much throttle is needed to proved the desired torque and opens the throttle to the required amount. This is good as it allows for changes in fuel types (spark blending moving from high to low tables), barometric pressure, air temps etc. So it makes the car feel more "constant" over a wide range of operating conditions. It's bad in that it messes badly with modifications as the torque model changes with each mod.

Without seeing any log data, I'd suggest that the ProCharger tune is a "base" tune and is meant to be a starting point for more work.

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Originally Posted by swingtan

1: If it's using the MAF, it won't use the VVE under boost conditions.
2: and 3: It all depends on what the exhaust AFR is. Commanding specific ratios does not actually mean that's what the engine is using. Stick a wideband in the exhaust and see what the engine is really using.
3: Command torque is the way of the future. The ECM maps the pedal position to a "desired torque" value. Then it uses the torque estimation tables to work out how much throttle is needed to proved the desired torque and opens the throttle to the required amount. This is good as it allows for changes in fuel types (spark blending moving from high to low tables), barometric pressure, air temps etc. So it makes the car feel more "constant" over a wide range of operating conditions. It's bad in that it messes badly with modifications as the torque model changes with each mod.

Without seeing any log data, I'd suggest that the ProCharger tune is a "base" tune and is meant to be a starting point for more work.

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What does the ECM look at to determine its fueling?

That's interesting about the commanded torque. So the throttle/gas pedal is no longer a direct tie to the throttle blade, but more of a power commander.

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Originally Posted by n8dogg

What does the ECM look at to determine its fueling?
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Other than Closed Loop, see Fuel->Open Loop and Fuel->Power Enrichment.

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Originally Posted by joecar

Other than Closed Loop, see Fuel->Open Loop and Fuel->Power Enrichment.

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So the E92 is fast enough to accurately fuel the engine without any airflow model?

Fast enough?

It's fast enough to calculate the VVE on the fly as well as the torque model and control the throttle..... It's not too much work to read the MAF and calculate the injector timing.

Personally, I think the main use of the VVE in the factory tune is to provide a secondary fuelling model in the event of the MAF failing.

Wow, OK, you learn something every day!

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Originally Posted by n8dogg

So the E92 is fast enough to accurately fuel the engine without any airflow model?

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It always calculates cylinder air first, even when CL/trimming.

Most Gen IV custom tunes / dyno tunes / etc. are setup in MAF only mode. EFILive is the only tuning software with native VVE tuning ability. That said, properly tuning the VVE is a labour intensive exercise - worth the effort to the enthusiast, but difficult to make commercially viable sometimes.

Dyno tunes generally range from $600 to $1000 - and will be setup in MAF only mode. These work OK, but in my opinion they are not as "crisp" as a well tuned blended VVE and MAF (OEM style) setup.

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Originally Posted by swingtan

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Personally, I think the main use of the VVE in the factory tune is to provide a secondary fuelling model in the event of the MAF failing.

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Hi Simon,

Yes, I agree, the MAF is used as the primary airmass model, and the VE/VVE is used when the MAF fails, and VE/VVE is used during throttle/airmass transients

( notice that I'm calling it airmass model rather than fueling model )

and it also seems to me that the VE/VVE is used to sanity check the MAF: if the MAF is causing the airmass model to significantly differ compared to VE/VVE, then it runs from VE/VVE until the MAF can be trusted again.

So most commercial shops are simply dialing in the MAF curve to get proper fueling?

Most "same day" Gen IV dyno tunes are MAF only. On a full build project you may (or may not) get a VVE and MAF tune - depends on the builder. The issue is the time involved (i.e. the cost) in a high quality VVE tune.

Most "USA" Tunes..... I'm not sure of the ratio here in n Aus. but a significant proportion are SD. My thought on this is that shops work on a "base" VVE for mods that are generally the same, then fine tune them for individual customers. The VVE can be made very close in just a few passes on the dyno, or 2 to 3, 2 hour drives on the street. The static VE can be dialled in much quicker.

Shops will do what ever they deem as necessary. Some may just tweak the MAF, some will use a base VVE, some will go the while 9 yards and do both the MAF and the VE. If I was doing MAF tunes for a job, I'd probably dial in the MAF and use a custom PID to give a correction map for the VVE. So I'd use the MAF airflow to correct the VVE. This would give a very good VVE for the minimal amount of effort, exactly what a shop needs to be competitive.

Hello Simon,

I agree with you as to what technique would work the "best". The day to day reality (at least in North America perhaps) for modified Gen IV ECMs, seems to be toward MAF only tunes. This may be driven by greed, time constraints, or lack of experience tuning in SD - or perhaps a combination of all. I have seen more than a few vehicles that were "dyno tuned", where the High Speed Mode RPM Enter (B8024) has been reduced from 4000 RPM to 400 RPM - meaning that they run off the MAF 100% of the time.

That said, there are very good tuners out there, who will give you your money's worth (and more) - it becomes very important to ask at the outset, what type of tune you are potentially purchasing.

Cheers,
Taz

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Originally Posted by Taz

Hello Simon,

I agree with you as to what technique would work the "best". The day to day reality (at least in North America perhaps) for modified Gen IV ECMs, seems to be toward MAF only tunes. This may be driven by greed, time constraints, or lack of experience tuning in SD - or perhaps a combination of all. I have seen more than a few vehicles that were "dyno tuned", where the High Speed Mode RPM Enter (B8024) has been reduced from 4000 RPM to 400 RPM - meaning that they run off the MAF 100% of the time.

That said, there are very good tuners out there, who will give you your money's worth (and more) - it becomes very important to ask at the outset, what type of tune you are potentially purchasing.

Cheers,
Taz

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I think there are a lot of factors that come into play that drives tuners to be quick with their tunes. I think a big factor is the lack of customer knowledge in tuning and their feelings on paying $100+ an hour. You get a lot of places advertise $300-$400 for a tune, trying to explain to customers the difference in a custom VE tune and a MAF only tune can be difficult.

It makes it difficult for someone like I, perfectionist by nature. Every tune I perform I'd like to be perfect, but there is always the fear of shocking the customer with the bill. It doesn't help that there is a local speed shop who specializes in GM Dyno (MAF only) Tuning.

Unfortunately, that is the nature of the typical customer...

they will go for the $400 tune (MAF only, peak dyno HP) rather than the $1,200 tune (MAF, VE, driveability), regardless of having spent $15,000 on an engine build.

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Originally Posted by n8dogg

1.) It appears as if the VVE tables have remained unchanged and the supercharger option has not been selected. What is this engine controller looking at to determine it's fueling?

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There is no reason at for the "supercharger" option to be selected with this controller at using our product at this time. Just as people do not use the Turbo functions, with other GM ECU's when running a supercharger on them. In the past we did tune the VVE tables with a lot of our GM tunes, as well as the MAF. However, we noticed no significant change in driving/starting/dyno/day to day operations, compared to MAF only. Yes, when dealing with a car with CAM modifications, or being dialed in to absolute perfection for ones fuel type/altitude/mods changing the VVE can have its advantages, however for just the blower being added to a stock car, we have not seen that.

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2.) The MAF table was scaled back, a lot... Wouldn't the added air being forced into the engine mean the MAF should be scaled higher?

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The MAF table is scaled for the correct amount of airflow that the MAF is now seeing, due to the location being changed to the blow through tuning structure.
This MAF table has a great deal of time spent in placement, to make sure it was getting the "cleanest" signal, as well has having plenty of range for those doing higher HP applications. We do this with every application before it gets put into final production, IE: the MAF is located in the intercooler in some of our GM applications, because that was the cleanest, most repeatable signal we could find. When we had our BETA development C7's undergoing MAF location testing, there was multiple intercooler locations, multiple draw through locations, and multiple blower through locations, before this location was deemed final.

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3.) The AFR was leaned out to 12.7, being forced induction, isn't this too lean? Maybe the direct injection system calls for a leaner AFR.

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That is the correct AFR that needs to be commanded for these cars to make max power, safely on these motors, with the stock cam and F/I. Please take the time to review other threads, internet white papers, and you will see that tuning this LT-1 motor like other "LS" motors, will result in lower power levels, washed down cyl walls, and fuel knock. Technically our tune is set up a little bit rich for our taste, but its easier for a customer to pull a little fuel out, then put a little in after it being to late.

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4.) What exactly is "commanded power mode, A, B, and C"?

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Others have already answered this.

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That's all, feel free to discuss!

Thanks

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Hope you enjoy the new found power!!! The C7 is a wonderful step for the Corvette, and adding boost is just that much better. I noticed in the other thread you talked about the car you did the install having headers. WITHOUT a doubt, that car will need a custom tune done if it had headers. We tested both AHR, and KOOKS headers on our cars here in house, and both brands required custom changes to our base tune to make them right. (And both brands changes varied as well, so the AHR tune, would not work correct with the KOOKS installed) Something to think about.

Awesome, thanks again for an informative response! I look forward to doing more ProCharger installs on these cars in the future!!

I can't believe that DI motors will hold boost with 12.7 AFR
but it seems that we will change our point of view with those new motors
any body know how much AFR will be safe for NA DI motors if the FI is holding 12.7 ?!!

We are currently tuning a cam,blower,stalled car right now. Stuck using HPT for the control they have. The A/F's are suppose to be lean and the blower drag brings up serious false knock.

Hoping EFI jumps on this tuning soon. I find it a lot easier to navigate.

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Originally Posted by n8dogg

Awesome, thanks again for an informative response! I look forward to doing more ProCharger installs on these cars in the future!!

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Your welcome, make sure you share your installs with us at socialmedia@procharger.com
Also we will be having a new website soon, where customers can easily create galleries for their cars, and update the specs, photos ect. :)

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Originally Posted by wesam

I can't believe that DI motors will hold boost with 12.7 AFR
but it seems that we will change our point of view with those new motors
any body know how much AFR will be safe for NA DI motors if the FI is holding 12.7 ?!!

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When working at Mercedes Benz, you would be surprised at what AFR's the new DI twin turbo cars run under WOT and boost. :)
Lots of info out there on DI and FI, however its usually related to smaller motors. Benz and a few others were really pushing the FI and DI combo on bigger V8's recently.
Only once the cars were "turned up" with a flash, would the AFR's start to even come close to what most people would consider "normal" Its just a learning curve, people will get used to it.

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Originally Posted by slowhawk

We are currently tuning a cam,blower,stalled car right now. Stuck using HPT for the control they have. The A/F's are suppose to be lean and the blower drag brings up serious false knock.

Hoping EFI jumps on this tuning soon. I find it a lot easier to navigate.

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Amen :)

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Originally Posted by wesam

I can't believe that DI motors will hold boost with 12.7 AFR
but it seems that we will change our point of view with those new motors
any body know how much AFR will be safe for NA DI motors if the FI is holding 12.7 ?!!

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Its not that its "holding it". The reality is that a boosted motor is set richer for cooling effect....much of the fuel mass is just wasted for the sake of cooling. Since DI injects fuel right into the combustion chamber the cooling effect is increased without the wasted fuel...hence a leaner lambda.

Much like the debate was on the GEN4 engine its the same here. 12.3 or 12.7......will depend greatly on engine dynamics. What you need to watch out for is this;

You can have the correct mass of air and the correct mass of fuel and still not measure the correct AFR due to injection timing and altered charge motion. Delivery the charge early or late will effect the reading in the exhausts.

Non boosted engines that get boosted will also start running into issues with charge motion effecting the injection flow path. GM has a million hours into the design of the LT1 chamber and the injectors are designed to have there spray pattern hit specific spots in the chamber....these spots will be effected by how the airflow enters the chamber...the calibration in the new ZO6 will show the ways GM addresses this...

Those that think its "easy" are only going to be hacking and whacking at the calibration. There is a right way to quantify all this.....:mrgreen:

Howard

Additionally to what Howard said about cooling effect, DI does not have to model wall wetting/evaporation of the head's intake port, so the mixture can be leaner since it does not have to contribute to the wall "puddle" (which has slower evaporation rate at boost compared to vacuum).

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Originally Posted by swingtan

Fast enough?

It's fast enough to calculate the VVE on the fly as well as the torque model and control the throttle..... It's not too much work to read the MAF and calculate the injector timing.

Personally, I think the main use of the VVE in the factory tune is to provide a secondary fuelling model in the event of the MAF failing.

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Actually its used more then we think but not as much as the MAF....when the engine goes into transient.....lets say a big throttle jab....the intake manifold acts like a big spring...the airflow being measured by the MAF is NOT what's making it into the cylinders. For this reason the SD logic kicks in looking at MAP/RPM to calculate the proper Grams/cylinder. Once the air signal gets linear it will revert back to the MAF signal until it sense enough of a delta to switch back.....there are several "flag" parameters that dictate this switch over but we can see them in EFIL...

Howard

Lingenfelter Stingray with a 2.3 charger/LPE cam on the stock injectors, no headwork . Not getting to WOT til middle of each gear due to tire spin. LT5 ZR-1 in the slower lane.

https://www.youtube.com/watch?v=0ZUp...ature=youtu.be

peace
Hog