Any feel like having a tuning discussion?

[ChevyHighPerformance]

I have HPTuners for the H3 and have been working on my own tune. I was wondering if anyone wanted to discuss tuning.

[Desert Dan]

What sort of HP and Tourque gains are you getting?

When you take it in to the dealer do they de-tune it?

[ChevyHighPerformance]

I didn't dyno before and after the tune yet - I'm still tweaking. The biggest thing I noticed was the low end torque and how much faster the H3 pulled out. My opinion only -> There are two major "flaws" in the stock PCM programming. One effects long-term engine durability and the other "flaw" I have never seen before in any other programs and makes even less sense to do this on the H3. The one flaw doesn't exist in the Colorado I5 tune which makes this confusing.

The dealer shouldn't touch the programming unless you tell them to. Unless they really know what they are doing, the dealer won't be able to tell that the PCM's program has been altered (unless they notice the performance difference). Cochran Hummer couldn't put on my mudflap correctly after they replaced my parking brake cable - so I really doubt they can detect a different tune. If they reflash the PCM you can just reload your modified tune or read in the new dealer flash and copy your new calibration tables over (timing, A/F, etc.).

[Wisha Haddan H3]

The tuning would have to be different between the 3.5 and 3.7L, right?

[f5fstop]

Originally Posted by ChevyHighPerformance

I didn't dyno before and after the tune yet - I'm still tweaking. The biggest thing I noticed was the low end torque and how much faster the H3 pulled out. My opinion only -> There are two major "flaws" in the stock PCM programming. One effects long-term engine durability and the other "flaw" I have never seen before in any other programs and makes even less sense to do this on the H3. The one flaw doesn't exist in the Colorado I5 tune which makes this confusing.

The dealer shouldn't touch the programming unless you tell them to. Unless they really know what they are doing, the dealer won't be able to tell that the PCM's program has been altered (unless they notice the performance difference). Cochran Hummer couldn't put on my mudflap correctly after they replaced my parking brake cable - so I really doubt they can detect a different tune. If they reflash the PCM you can just reload your modified tune or read in the new dealer flash and copy your new calibration tables over (timing, A/F, etc.).

You say one affects long term engine durability, and the other flaw you don't mention. Just curious, what are these flaws and how does one affect long term engine durability?
If these are legitimate, I have no problems confronting Johnny boy, one of the programmers. I do know there had to be different programming parameters for the H3 engine, even if it is used as an optional engine on the C/C trucks.

But I would also be curious to know how your program would be any better, and what long term durability tests you have done. I do know that there are some H3 EX VIN production vehicles running around with over 100K-125K and only problem with one of them was a replaced cylinder head, an issue well known to most of us here on the Forum. (Sorry guys, the ones I have seen have not made the trip outwest to test long term driveline durability; these are engine/trans long term test vehicles. The driveline ones are in Mesa - where I would love to be - or Kapuskasing, Canada - where I would hate to be.)

If, as you say there are flaws, I'm sure the programming people would be very interested in the data that shows the flaws.

As for a dealer knowing if there is a reprogram to the vehicle. I agree, only the top 5 percent of tech would ever know a non-factory program was on the vehicle, and then only if they actually took the time to sit down and think, and even most regional service engineers would not notice the fact if called in for an engine controls problem.

Is it possible to re-flash to the original program if necessary, and then re-flash back to the custom program?

[Desert Dan]

What controls the deceleration of the engine between shifts?
I have the 5-speed and you can feel and hear the engine slowly slowing down between shifts.

Also it seem when going down hill in gearthe throttle doesn't completely back off. I feel like some of the compression braking is missing and miss the slight rumbling and backfire? This must be an emssion control thing

[ChevyHighPerformance]

Originally Posted by Wisha Haddan H3

The tuning would have to be different between the 3.5 and 3.7L, right?

The tuning methodology would be the same. The actual tables will be different. For example, the volumteric efficiency tables have the same format but different numbers. HPTuners is suppose to be able to tune the 07's very soon.

[ChevyHighPerformance]

Originally Posted by Desert Dan

What controls the deceleration of the engine between shifts?
I have the 5-speed and you can feel and hear the engine slowly slowing down between shifts.

Also it seem when going down hill in gearthe throttle doesn't completely back off. I feel like some of the compression braking is missing and miss the slight rumbling and backfire? This must be an emssion control thing

I know what you mean. When you press in the clutch it takes a while for the RPMs to come down. I tweaked this on a different electronic throttle control vehicle using a throttle follower table that controls how fast the RPMs decay to match the commanded throttle position. This table exists for other vehicles but I don't see it listed for the H3. My guess is that HPTuners did not include this table in this version, but I know Colorado I5 people have the same concern so maybe in the next version this will be included.

There are DFCO (deceleration fuel cut off) settings that may need tweaked.

[H3slate]

So it improved HP and torque? What about mpg? I am also interested in a legitimate way to get a little more from my engine.

[ChevyHighPerformance]

Originally Posted by f5fstop

You say one affects long term engine durability, and the other flaw you don't mention. Just curious, what are these flaws and how does one affect long term engine durability?
If these are legitimate, I have no problems confronting Johnny boy, one of the programmers. I do know there had to be different programming parameters for the H3 engine, even if it is used as an optional engine on the C/C trucks.

But I would also be curious to know how your program would be any better, and what long term durability tests you have done. I do know that there are some H3 EX VIN production vehicles running around with over 100K-125K and only problem with one of them was a replaced cylinder head, an issue well known to most of us here on the Forum. (Sorry guys, the ones I have seen have not made the trip outwest to test long term driveline durability; these are engine/trans long term test vehicles. The driveline ones are in Mesa - where I would love to be - or Kapuskasing, Canada - where I would hate to be.)

If, as you say there are flaws, I'm sure the programming people would be very interested in the data that shows the flaws.

As for a dealer knowing if there is a reprogram to the vehicle. I agree, only the top 5 percent of tech would ever know a non-factory program was on the vehicle, and then only if they actually took the time to sit down and think, and even most regional service engineers would not notice the fact if called in for an engine controls problem.

Is it possible to re-flash to the original program if necessary, and then re-flash back to the custom program?

It is possble to reflash to the original programming. You can either write the calibration data only or flash the entire operating system (for using a PCM for another vehicle). Reflashing the calibration data only takes about 40 seconds.

I start be reading in the existing PCM's program, tweaking the tables, then rewriting the new calibration data.

I am in the early stages of evaluating someone else's tune. I want to see if they find these "flaws". Actually, another channel is open with GM to discuss this along with new auto tranny shift speed trajectories to improve MPG, high octane and low octane timing tables, ECT and IAT timing adders.

The durability issues surfaces with a certain type of driver. Someone tried this "flaw" to intentionally limit power on the dragstrip to limit their ET to meet NHRA rules for their LS1 ragtop. This flaw forced the engine to operate in region where it shouldn't have. I know that H3's aren't for the dragstrip, but this was a real-life example of what could happen.

I haven't done any durability tests. I have never ever seen anyone do this in a program before. For an extreme example, if I told you that I am going to run a 20:1 air fuel ratio, do you really have to run a long term test to judge the durability versus a 14.7:1 A/F engine?

[ChevyHighPerformance]

Originally Posted by H3slate

So it improved HP and torque? What about mpg? I am also interested in a legitimate way to get a little more from my engine.

I haven't run through a full tank with my normal driving yet. I've been taking a few highway trips which is going to skew my normal 100% city MPG high. So far, every other tuner I spoke with stated an increase in MPG.

[H3PAC]

I would assume that the expert engineers at GM would have already programmed the vehicle to perform optimally - i.e. the best combination of power/fuel efficiency/emissions, etc. I see programming devices advertised for sale to the conusmer and I wonder, why would an amateur playing around with these settings be able to do a better job than an entire professional team? Please don't misunderstand me - I don't mean to be disrespectful, I'm just trying to understand what the goal of reprogramming is. Can anyone please clareify this?

[ChevyHighPerformance]

Originally Posted by H3PAC

I would assume that the expert engineers at GM would have already programmed the vehicle to perform optimally - i.e. the best combination of power/fuel efficiency/emissions, etc. I see programming devices advertised for sale to the conusmer and I wonder, why would an amateur playing around with these settings be able to do a better job than an entire professional team? Please don't misunderstand me - I don't mean to be disrespectful, I'm just trying to understand what the goal of reprogramming is. Can anyone please clareify this?

First of all I really like GM, and I never bought anything other than a GM vehicle.

I some cases I agree with your thoughts. However, the amount of testing on the C6 Corvette&Z06 was way more extensive than the H3. So the tuning of the Corvete is much closer to optimal than the H3's, in my opinion. I feel GM has limited money/resources which limits development. Also, GM has to design to some extreme conditions such as temperature, fuel grades, etc which dictate the amount of conservatism in the tuning. For example, I think there is a TSB for the I5 for rough idle requiring a PCM reflash. So there is one example of where the experts didn't take everything into account the first time. OK, so everyone makes mistakes.

For example, if you have good quality gas and you don't operate in extreme temperatures, you can re-optimize you programming to your environment. Ask any tuner what the optimum A/F ratio is for best power and you'll get something like 12.8 - 13.1:1. However, GM has a 11.3 commanded A/F ratio for wide open throtle (WOT) for max power. Why? 11.3 is more conservative and provides more margin in case of problems. However, if you have a custom tune you can get the optimal A/F for more power. The same can be said for the timing or torque managment.

It's not that GM doesn't know how to optimise performance (look at the C5R), but is forced to for manufacturing tolerances, warranty issues, etc.

So a custom tune is one made for your vehicle - kinda like a custom suit.

[Hal]

Feel free to give those of us who are interested, but by no means experts, links to any refrences where we can learn more about this stuff.

Keep the info coming, I like this topic

Like I always run premium gas, have a 5-speed and live in a hot southern climate... I never thought about optimizing an engine for things like this.

[f5fstop]

Originally Posted by ChevyHighPerformance

It's not that GM doesn't know how to optimise performance (look at the C5R), but is forced to for manufacturing tolerances, warranty issues, etc.

So a custom tune is one made for your vehicle - kinda like a custom suit.

I agree with Chevyhighperformance on this one; GM does have to produce a calibration that is designed for all factors, where a custom tune can increase performance. I had one on one of my Vettes, and it worked well. This was a custom tune loaded by a LS1 program, not a standard tune off a hypertech type device. Most of the standard tunes on the hypertech type devices are not much help.


As for testing, I understand that no tuner does long term testing prior to releasing a tune; the purchaser becomes the tester. What I was implying is your statement that there was a durability fault with the existing program (and which one, there have been at least two different updates since introduction, and there might be more, I haven't checked in a few months), and GM has quite a few production vehicles out there with high mileage; and some very early mules with tons of mileage, and no major durability problems I know of have been found. Those that were found, were updated with a new calibration, and then nothing really fixed in the new cals with durability.

[ChevyHighPerformance]

Originally Posted by f5fstop

As for testing, I understand that no tuner does long term testing prior to releasing a tune; the purchaser becomes the tester. What I was implying is your statement that there was a durability fault with the existing program (and which one, there have been at least two different updates since introduction, and there might be more, I haven't checked in a few months), and GM has quite a few production vehicles out there with high mileage; and some very early mules with tons of mileage, and no major durability problems I know of have been found. Those that were found, were updated with a new calibration, and then nothing really fixed in the new cals with durability.

I see two types of tune: performance and luxury. For the Corvettes, Silverado SS's, and F-bodies, performance is the goal and I'll shoot for a 12.8-12.9:1 A/F at WOT. For the H3 (first luxury tune), MPG is primary then performance and I'm shooting in for a 12.2:1 A/F under WOT. From what I remember on a 350 HP LS1 a 13:1 produced about 3-4 more HP at the wheels than a ~12:1 A/F. So for the H3 at 220 HP, the extra 2-3 HP at 13:1 isn't worth running closer to the edge.

As I go through with a tune, I try to identify the vulnerabilities - where is the engine stressed the most and how much relative stress. I shoot for having the most stress at WOT. However, some tuners leave voids and if you operate the engine in this region the engine stress is excessive.

I've done some tuning and published articles on how to tune, but I don't consider myself a pro like Bryan Herter or Steve Cole. That is one reason why I started this thread to solicit opinions from other people who are tuning.

[ChevyHighPerformance]

Originally Posted by Hal

Feel free to give those of us who are interested, but by no means experts, links to any refrences where we can learn more about this stuff.

Keep the info coming, I like this topic

Like I always run premium gas, have a 5-speed and live in a hot southern climate... I never thought about optimizing an engine for things like this.

Here is a link to LS1TECH that has other links about tuning.
http://www.ls1tech.com/forums/showthread.php?t=287094

I really haven't read through the stuff listed here but it came highly recommended.

[ChevyHighPerformance]

Just an update. With the new increase in low end torque, I modified the auto tranny shift speed table. This table shows at what MPH and throttle position you want the tranny to upshift or downshift for each gear. I lowered the MPH at which the tranny up shifts and I moved out where the tranny down shifts - I added more hysteresis. So when you are doing 60 MPH and you press on the throttle slightly the tranny doesn't down shift to 3rd right away. I get into 4th gear much quicker now and the acceleration in 4th is fine for small-medium grades. If I need more acceleration, I just blip the throttle more and the tranny will downshift. The stock shift tables can cause you to downshift (4th to 3rd) if you increase the throttle by as little as ~12%.

For low throttle positions I upshift quicker for better (hopefully) MPG. When you need the acceleration the new shift table doesn't hold you back.

[ChevyHighPerformance]

Another update. I've tweaked the tranny shift table several times. Not very scientific but - now it feels like the H3 floats/coasts. Before it always seemed like I always had to press on the throttle just to coast around town (as if I was dragging something behind me).

Also, in my plan the speed limit is 25 (lots of kids) and my plan is pretty hilly. Before I had to press the throttle to climb a hill but to keep speed going down the other side I would just let off the gas and I would maintain speed. Now, I have to press the throttle less to climb the hills and when I go over the peak, I let off the gas and I accelerate down the hill and have to use my brakes.

I know its not scientific, but now the H3 seems "lighter".

[wpage]

Originally Posted by ChevyHighPerformance

Another update. I've tweaked the tranny shift table several times. Not very scientific but - now it feels like the H3 floats/coasts. Before it always seemed like I always had to press on the throttle just to coast around town (as if I was dragging something behind me).

Also, in my plan the speed limit is 25 (lots of kids) and my plan is pretty hilly. Before I had to press the throttle to climb a hill but to keep speed going down the other side I would just let off the gas and I would maintain speed. Now, I have to press the throttle less to climb the hills and when I go over the peak, I let off the gas and I accelerate down the hill and have to use my brakes.

I know its not scientific, but now the H3 seems "lighter".

CHP Good Thread! Kindly monitor your MPG closely as you probe these tests. You are on to potentially significant info. Please continue to share your findings.