Any feel like having a tuning discussion?
 

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

Re: Any feel like having a tuning discussion?
 

What sort of HP and Tourque gains are you getting?

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

Re: Any feel like having a tuning discussion?
 

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.).

Re: Any feel like having a tuning discussion?
 

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

Re: Any feel like having a tuning discussion?
 

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?

Re: Any feel like having a tuning discussion?
 

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

Re: Any feel like having a tuning discussion?
 

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.

Re: Any feel like having a tuning discussion?
 

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.

Re: Any feel like having a tuning discussion?
 

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.

Re: Any feel like having a tuning discussion?
 

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?

Re: Any feel like having a tuning discussion?
 

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.

Re: Any feel like having a tuning discussion?
 

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?

Re: Any feel like having a tuning discussion?
 

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.

Re: Any feel like having a tuning discussion?
 

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 :excited:

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. :cool:

Re: Any feel like having a tuning discussion?
 

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.

Re: Any feel like having a tuning discussion?
 

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.

Re: Any feel like having a tuning discussion?
 

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.

Re: Any feel like having a tuning discussion?
 

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.

Re: Any feel like having a tuning discussion?
 

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".

Re: Any feel like having a tuning discussion?
 

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.:beerchug: :beerchug: :beerchug:

Re: Any feel like having a tuning discussion?
 

I use EFI LIVE for my dmax and it does a great job, hoping that they will work on the H3 soon.

A lot of guys on another forum use it and we trade files, plus my vendor sent me a 500+ RWHP race tune for my truck once the tranny gets upgraded.

diesels are much easier to play w/ AF doesn't matter really.

I've got a tune right now that gives me 60hp and 4 mpg better fuel mileage as long as u stay under 72mph.

It gets addicting playing w/ the tuning to see what u can do, the speed limiter and redline was the first things to change plus calibrate the speedo.

Re: Any feel like having a tuning discussion?
 

CHP,
I'm really interested in your programming results, so keep the updates coming. So where would an owner search for a reputable programmer that we could trust to develop a "custom" program for our H3?
Hokie

Re: Any feel like having a tuning discussion?
 

do it your self?

Re: Any feel like having a tuning discussion?
 

I know what you mean. I keep tweaking and tweaking when I'm probably way beyond the point of diminishing returns. I'm having fun - I'm a nerd.

Re: Any feel like having a tuning discussion?
 

Alvin from PCMforLess is tuning the H3's now. Typically you pay a deposit for a loaner PCM (which is sent to you first) and tuning. You remove your PCM, install the loaner, and send your PCM to them to tune. Then exchange the stuff when they ship your PCM back to you.

We use the same tuning program - so they sent me one of their tunes electronically to check out. I'm going to evaluate the tune in 3 stages:

1) Look at the actual tune - what and how tables were modified,etc. - This lets you gauge how the tuner made improvments, the tuner's philospohy, etc.

2) Install the tune and run a few tanks of gas through. SOTP testing, MPG testing, etc.

3) If I have time, I'll do a before and after dyno.

I plan on posting the results here as well as how my own tune is coming along.

Re: Any feel like having a tuning discussion?
 

does HP list the history of changes made to a tune?

efi does, so even w/ different OS all I have to do is write down all the tables that are changed then cut and paste.

It is fun to play, dad wants me to tune his 99 vette now.

Re: Any feel like having a tuning discussion?
 

HPTuners maintains a complete history log for your file. It shows when you made the change and what you changed.

Re: Any feel like having a tuning discussion?
 

Another update. I just added about 15 gallons of gas. The MPG was 14.7. My driving is 100% city with trips less than 5 miles and hilly roads.

Previous MPG data:

1) With the modified aftermarket air box, ported throttle body, exhaust and a couple other little things I was getting a solid 13.5 MPG.

2) I faked the Inlet Air Temperature sensor (IAT) out with a resistor and added resistance in series with the Engine Coolant Temperature sensor (ECT) to get more timing. With the resistors, I would get between 14 (mostly) to 14.5 MPG.

The resistors were removed for the latest test since I had direct program control and I didn't need to "trick" the PCM.

During this 15 gal test run:

1) I modified the shift trajectory several times part way through. So the full effect of this is not known.

2) I made many wide open throttle (WOT) runs to check on timing, knock retard, and tranny shifting. The WOT runs hurt the MPG.

3) It's been colder so I idle more in the mornings before I pull out which hurts MPG.

The results are encouraging but this is just one data point.

Re: Any feel like having a tuning discussion?
 

F5 - Are these tunes legit? If so, why wouldn't GM be offering them? I just happened to see a show the other day where an ASE Tech Inspector witnessed an HP test at GM. It was really cool how they did it... Glad to know that such tech claims are third party regulated (kinda like a UL for the auto industry and no offense to GM). This keeps everyone honest... :shhh:

Re: Any feel like having a tuning discussion?
 

Having worked for several major Tech Companys. R&D has deadlines and comitments on projects. Often they do not own or have significant interest in products in the pipeline. They kick products out the door. Under the Just in time banner, ready or not. GM has great people however my moneys on CHP to tweak this thing since he has ownership and apparently commitment.:) :) :)
The H3 is still young and has some growing to do...Its a great machine but like the 55 chevy there still may be some tweaking to discover and have fun with!!

Re: Any feel like having a tuning discussion?
 

I know you didn't ask me, but I feel the tunes are legit. I just loaded Alvin's tune (from PCMforLess) and the idle was very smooth and the low end torque boost is impressive (it was much better than my custom tune). Throttle is very responsive down low.

Re: Any feel like having a tuning discussion?
 

CHP - how long did it take you to complete this process?

Re: Any feel like having a tuning discussion?
 

The initial tune took about an hour to modify tables for a baseline. Then to "calibrate" the MAF took about 1/2 hour. Modifiying the shifting tables is 10 minutes each time, but then I go for a 20 minute ride to see how it feels then tweak again.

From looking at Alvin's tune (from PCMforLess) there is more I could/should have done. For example, I modified the timing tables by adding timing evenly everywhere. Alvin's timing table shows that he did additional work in certain locations above what I did, and he modified some tables that I missed.

I guess to start from scratch and to produce what Alvin did would take several days of tweaking and road testing.

Was this what you were looking for?

Re: Any feel like having a tuning discussion?
 

GM and others are after emissions stuff 1st and reliabilty/warranty 2nd (maybe).

got to keep the epa happy.

that's why they have so much torque management off idle, save parts I'm sure.

I know on the diesels it used to be u had to roll out black smoke to make power but w/ EFI we can make more power and very little smoke.

stock Dmax (LLY) is close to 600 rwhp or more w/ tuning and diesel only.
year ago 500 was really tough to get.
but an allison will only handle 350-400 though w/o upgrades.

Re: Any feel like having a tuning discussion?
 

Here is some new fuel economy test data.

First, the goal was to test my modified tranny shift table versus the one supplied from Alvin in his tune.

There are two elements to fuel economy: acceleration efficiency and cruise efficiency.

CRUISE EFFICIENCY

For highway traveling, the goal is to maximize the cruise efficiency. For example, for a typical vehicle the amount of gas it takes to accelerate from 0 to 60 MPH is about the same amount required to keep the vehicle traveling 60 MPH for about a mile. So you can see that when you are traveling many miles the amount of gas used to accelerate you is very small compared the amount of gas you?ll use to keep you at speed for many miles. This sets up my first test for which everyone probably already knows the results. I ran the H3 at two fixed speeds (40 MPH and 44 MPH) in both 3rd and 4th gear and measured the rate at which the gas is consumed. (The gas volume was measured and since the temperature was constant for all tests the volume is reflective of the mass of gas used.)

3rd gear:

40 MPH - fuel utilization rate = 3.38u/s

44 MPH - fuel utilization rate = 3.92u/s

4th gear:

40 MPH - fuel utilization rate = 2.90u/s

44 MPH - fuel utilization rate = 3.05u/s

u/s is a scaled volume of gas used per second

The conclusion here is that if you are cruising you want to be in the highest gear with the torque converter locked. My guess is that even though the drivetrain efficiency is higher in 3rd than 4th gear, the higher engine parasitic losses associated with the higher RPMs in 3rd than 4th gear dominated the fuel rate utilization.

ACCELERATION EFFICIENCY

For city traveling, the goal is to maximize the acceleration efficiency. If you are starting and stopping every block then the amount of gas used to accelerate the vehicle will dominate the fuel consumption and MPG. The trick the hybrids do is absorb energy and store it during braking; then use this stored energy to accelerate the hybrid. This is why the hybrids do proportionally better in the city than the highway.

I ran the H3 at three different constant throttle positions (35%, 45%, and 55%) and measured the total fuel volume used when going from 20 to 50 MPH. (The gas volume was measured and since the temperature was constant for all tests the volume is reflective of the mass of gas used.) I ran this test for both my tranny shift tables and Alvin?s tranny shift tables.

My tranny table

35% throttle: time=28.8 sec, total gas used = 3583u total

45% throttle: time=15.8 sec, total gas used = 2945u total

55%+ throttle: time=13.1 sec, total gas used = 2567u total

Alvin?s tranny table

35% throttle: time=29.3 sec, total gas used = 3803u total

45% throttle: time=12.0 sec, total gas used = 2473u total

55% throttle: time=11.1 sec, total gas used = 2508u total

u total is a scaled amount that represents the total gas volume used

Because it was difficult to precisely hold the throttle in a fixed position there is some variance (maybe +/- 5%) about each time and total fuel used data point. There are two conclusions from this test: 1) Alvin?s table resulted in less fuel consumption than mine and 2) the more throttle you use to accelerate (within reason) the less fuel you use. This goes against the EPA?s advice to not accelerate fast when pulling out because you?ll waste gas. I think the reason why the higher throttle resulted in less total fuel being used is due to the lower pumping losses associated with larger throttle positions thereby increasing the engine?s overall efficiency. Basically, your engine doesn?t have to work as hard to suck air into the engine when the throttle body is open more.

I think the key is learning how to drive based on how the tranny tables are set up. I think my tables are better for cruise (highway) and Alvin's are better for acceleration (city).

Re: Any feel like having a tuning discussion?
 

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.

Re: Any feel like having a tuning discussion?
 

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.:)

Re: Any feel like having a tuning discussion?
 

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

Re: Any feel like having a tuning discussion?
 

CHP,
Thanks for clarity. Did you opt to keep your stock Tuning set up on the flash upgrade as a fall back? Or take the plunge and trade in for the performance tune?:popcorn:

Re: Any feel like having a tuning discussion?
 

How HPTuners works is that you first read in your stock program through the diagnostic port and save it on your laptop using the HPTuners interface. Then you edit the stock program using a PCM editor program (comes with HPTuners). Then reload your modifed program. You still have the stock program to reload at any time. It takes less than a minute to load a program to your PCM.

HPTuners also comes with a OBDII scanner that lets you monitor/log all of the PCM parameters (no BCM, ABS, etc.), view diagnostic trouble codes, clear codes, etc. that you can use with any GM OBDII vehicles. For the vehicles that you have licenses for you can control the PCM on the fly. For example, you can change the commanded A/F, timing, turn off/on things like the fuel pump, peform a CASE relearn, cylinder balance, etc.