First time with HP Tuners, seeking advice for getting started

gmcman

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Dec 12, 2011
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I plan to also use this on other vehicles in the future, but curious to get my feet wet with the 02 Envoy, I figure this will also be a good thread for anyone diving in. The program seems straightforward despite the learning curve.

I have a spare PCM from an 04, this was going to be the "test mule" but unsure of the gear ratio, and until recently I searched the site to find out this may or may not be adjustable. Basically anyone that has used this software if you have any advice to offer to avoid any pitfalls would be greatly appreciated. Saving a copy of the current tune I assume would be first and foremost...:thumbsup:
 
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Mooseman

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Dec 4, 2011
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How timely. I'm also planning on getting it for myself for my fleet as well as do a side hustle of disabling DOD/AFM and other minor mods to tunes.

I have a spare PCM from an 04, this was going to be the "test mule" but unsure of the gear ratio, and until recently I searched the site to find out this may or may not be adjustable.

The way I understand it (@limequat can confirm) is that the speedo/gearing can't be changed using HPT however, it may be changeable by reprogramming the stock tune with the VIN of a truck with the gearing you need using a Tech 2 and Tis2000. I don't know if it's a calculation that Tis2000 does or it has a table of the gearing vs the VIN but I have a feeling that's how it's done. I've reprogrammed PCM's and it doesn't ask for the gearing.

I think any PCM you want to use has to have the stock tune for your truck so the 04 PCM would need to be reprogrammed for your 02.
 
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gmcman

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I think any PCM you want to use has to have the stock tune for your truck so the 04 PCM would need to be reprogrammed for your 02.

I'm assuming I could save the tune of my stock 02 and copy to the 04 PCM. That I need to look into but will have to wait till the weekend.

I only installed the software and took a quick peek at the program, this was nice to see though. :thumbsup:

Screenshot_20200925-160805_Gallery.jpg
 
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limequat

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Dec 8, 2011
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The way I understand it (@limequat can confirm) is that the speedo/gearing can't be changed using HPT however, it may be changeable by reprogramming the stock tune with the VIN of a truck with the gearing you need using a Tech 2 and Tis2000. I don't know if it's a calculation that Tis2000 does or it has a table of the gearing vs the VIN but I have a feeling that's how it's done. I've reprogrammed PCM's and it doesn't ask for the gearing.

This is correct. HPT just never hacked the P10 well enough to find the gear ratio or tire size calibration. The work around is to start with a PCM that already has the gear size you need.
 

mrrsm

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...and if you want to work with your "Guinea Pig" 2002 P10 PCM while in the confines of your home with all of the requisite gear nicely laid out on a table... I've got a dedicated thread on "How to Create a Bench Top Test Harness for the Early Model LL8 Engine P10 PCM" that will allow your experimentation to happen under more 'comfortable' settings than doing so while sitting inside of the SUV after having to Swap PCMs In and Out ...Ad Infinitum...:

If you intend upon making a more complete Bench Top Harness for the Later Model PCMs for the 4.2L Engines... Please refer to Bill Reid's Thread and follow THIS Schematic which includes OTHER Modules Interfaces:

Benchtop P10 Rev0_1.jpg
However... If you want to use the design I modeled to some extent from Bill Reid's Work... These images show what I managed to make that worked PERFECTLY and would certainly be suitable for using with your HP Tuners HW and SW in a Bench Top Setting. I would recommend attaching the AC/DC 110 to 12 Volts DC - 1.5 Amp Power Supply to a 500-700 Watt Battery Back-Up Unit to prevent "lunching" the PCM during any Reads-Writes due to sudden and otherwise dreadful "Power Outages":

Benchtop P10 Rev0_1.jpgBULLREIDSSUBSET.pngFINALGYMKOHARNESSPINOUTS.jpgOBD2TOC1BLUEANDC2NAT.jpgC2WHITETOOBD2.jpgC1BLUETOOBD2.jpgPROOFOFCONCEPT0.jpgDSC01353.jpgDSC01361.jpgDSC01362.jpgPROOFOFCONCEPT2.jpgPROOFOFCONCEPT3.jpgPROOFOFCONECPT4.jpgDSC01361.jpgDSC01363.jpgDSC01364.jpgDSC01366.jpgDSC01367.jpg

If you decide to delve deeper into how this is done... Read from Post#2 through to Post #22 in this Thread for all of the "Step-By-Steps" in making things work right:

 
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gmcman

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Very cool @MRRSM , I'll check it out, thanks.

It appears I can alter the VSS parameters and trans revs, I assume that could offset any gear ratio differences.
 
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mrrsm

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...but remember that you'll have to confirm that your PCM Calibration changes are also in the ACDelco PCM Calibration List for the Power Train Control Module RPO Listings... or things may not look right once you write that calibration to the PCM. Take a "Snapshot" of your RPO Sticker (De-Cypher it...) and keep it handy on screen when you are looking things over.

Try not to freelance too much with HP Tuners Right off the Bat... Good Science means "Only Change One Parameter at a Time"... especially since the P-10 PCM is NOT one of their favorites without any great depth of experience when performing any changes to it. You Don't want to "surprise" your 4L60E Transmission with anything Too Rambunctious that might damage it in the long run.
 
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gmcman

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Good words of wisdom, thanks! Yes, going to take it slowly for sure.

You Don't want to "surprise" your 4L60E Transmission with anything Too Rambunctious that might damage it in the long run.

That's another area I surely don't want get too carried away with. I think I'm nearing the "long run" for sure at 310K.

I would like to raise the RPM at which the converter locks, somewhere above 1600 as it will lock now at 1400-1500 at times with the PWM eliminator kit.
 
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mrrsm

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I might be wrong on this... But... IIANM... The Trailblazers and Envoys sporting the 4.2L 4L60E Transmissions came Stock with a 'very much in demand' Torque Converter that could handle the Additional Power from an LS Engine Cammed with the need for a Higher RPM Stall 'Sweet Spot'.

Supposedly our TCs are in the 2200 to 2400 RPM Stall Range. This information was gleaned from several different reads around the LS Performance Sites on the Internet and this came as quite the surprise to me. The Better Informed about this Transmission vs. the Torque Converter Stall Settings might give added clarification.

I'm not certain that locking up the gears at such a low RPM Threshold would be an advantage... but you must know why this is necessary...
 

gmcman

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I'm not certain that locking up the gears at such a low RPM Threshold would be an advantage... but you must know why this is necessary

Actually mine is locking quite early, maybe from having the 4:10 gears. Sometimes it will lock at an easy cruise around 45 MPH @ approx 1400 RPM. I would like to delay that until about 1600-1700 RPM at the earliest.

I feel 1400 is likely hard on the rod bearings, could be wrong.
 

mrrsm

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The effect of locking up the Torque Converter at low speed with the 4:10 Diff Gears would not be as hard as it would be with the 'tail end' at 3:43 more useful when trying to achieve a road speed of 75-80 MPH and having the Engine RPM settle out below 2,000 RPM.

This must be the Thread that you documented those changes in back in April of 2013:


These are two more interesting reads that relate to the use of the 4L60E Transmission in the 2004 Trailblazer that could add information about these issues with additional sub-links on other 4L60E matters as well:



RPO/Axle Codes:

 
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gmcman

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Dec 12, 2011
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I agree, with less load on the engine it's likely to lockup sooner.

Here's two screenshots of my stock tune in regards to the TCC lockup, It could modify the road speed at which the TCC locks as long as I keep the release speed lower as depicted in the graph.



NORMAL

Normal TCC Apply.jpg


PERFORMANCE

Normal TCC Apply.jpg

So basically my 4th gear lockup speeds are 37 and 41 MPH depending on the graphs. If I change those speeds to maybe 45 and 50 MPH respectively, would the trans be trying to use the PWM signal to lock the converter for an extended period of time, or does it not begin until the lowest set speed? I assume the latter but curious to know. Not sure if anything happens before those lowest speed settings that's not shown on the graph, but figure it's accurate and shows all the info.
 

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mrrsm

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The biggest consideration will be the Local Road Grades and whether your surroundings are well above Sea Level (say... Just Under Pike's Peak in Elevation with any Sketchy or lingering MAF issues) as these would come into play if you regularly Tow anything Fairly Heavy ...up and down such a Mountainous Terrain.

Spend some time viewing "The Sloppy Mechanic's" HP Tuners Seminars and look for the Reliable HP-Tuners Online Resources that have stored files from people who may have already sorted out your 4L60E Issues that have almost Identical Equipment to your own. He has the greatest amount of Practical Experience with NA and Boosted Hardware and High Performance Camshaft issues with the LS Motor Platform. Here is an excellent example:


...and here are many more:

 
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