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?

[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.

[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 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.

[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 ChevyHighPerformance

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.

OK, the first item is the AC. The scenario is that you are trying to accelerate quickly onto a highway and the AC is on. On the vettes, f-bodies, etc. the AC will kick out above a certain RPM and throttle position. We all know the H3 doesn't have excess power but the AC never kicks off. Even though the AC takes a few HP when cruising it robs a bunch more at high RPMs. So I think the AC should kick off above perhaps 60% throttle and maybe 4000 - 4500 RPMs to reduce engine drag to get you accelerated quicker and I think would reduce wear on the AC compressor (maybe not the clutch though). When you drop below these setting the AC re-engages. During the 5 - 10 seconds while the AC is off, I don't think the cabin is going to get that hot so your balls stick to your leg. Every pro tuner I talked to agreed with this and doesn something similar for their tunes.

The other item needs some background. The engine operates in many modes but the two of issue is part throttle and WOT (wide open throttle). During part throttle, the PCM monitors the pre-cat O2 sensor and effectively adjusts the injector pulse width to maintain a 14.7:1 A/F ratio. The 14.7:1 A/F results in the lowest overall emissions and good fuel economy (best fuel economy is at about 15:1 A/F). During WOT or power enrichment, the PCM richens the A/F, provides more timing, and uses different auto tranny shift points for more power and maximum acceleration.

The boundary between these two mode is based on the throttle position. The vettes, f-bodies, I5 colorado/canyon, etc. enter WOT above 80% throttle. The H3 enters WOT above 94% throttle. I can see how minimizing undesired excursions into WOT will help fuel economy. The other issue is that running the engine pretty much flat out (93.9 % throttle) at such a lean A/F. I talked to several pro tuners about this and there was not unified position. One tuner gave an example (keep in mind the A/F for max power is about 13.1:1) that you could tune WOT for 13.1: and you'd make great power but the life of the engine is going to be reduced and 14.7 at essentially WOT is going in the wrong direction - so this tuner keeps the the WOT A/F to about 12.8ish and bumps up when you enter WOT (lower throttle position). Another tuner said that with the stock programming when you go to WOT the PCM delays several seconds already (so you are running at 14.7:1 at WOT) before power enrichment starts anyway. I don't know who is truly correct. I guess it depends on how you drive. For example, if I told you to press on the throttle and tell me what percentage you are at (0 - 100%) you might say 40% when you are actually at 70%. I am going to log some data and see what %throttle normally drive at and what peaks I hit when I don't want to goto WOT. I'll then set the WOT entry to be above the maximum I use when I drive.

[wpage]

CHP,
This is alot to digest. Your baselines are reaching the high end of where I am willing to go on this topic. Are you still working on a basicly stock engine? Cat Back Exhaust? Intake Mods? Some of this may be skewed for some of us. Please digress if you would to keep us on track with your tests...
This is interesting data. However getting deeper.

[ChevyHighPerformance]

Originally Posted by wpage

CHP,
This is alot to digest. Your baselines are reaching the high end of where I am willing to go on this topic. Are you still working on a basicly stock engine? Cat Back Exhaust? Intake Mods? Some of this may be skewed for some of us. Please digress if you would to keep us on track with your tests...
This is interesting data. However getting deeper.

Stock engine with main mods: after market cold air intake, ported throttle body, and cat back exhaust.