L96 GMC Savana 4500 swap Into Squarebody - Tune Posted

[Jeepguy25]

Hi All! Last year I completed my swap on my 88 Suburban. I used a 2012 L96 and 6L90 from a GMC Savana 4500 van. It was a people carrier I THINK. It was too smashed up in the pics to tell. In any case, I had lots of questions about the 6.0 that was in it and how the tune would compare to the consumer version in the trucks. It was a bit of a mystery, but it turns out the engine is physically the same as far as I can tell.

My common sense tells me that the tuning on a commercial vehicle has to be different than a consumer model. Much more conservative to save on parts, not necessarily save on fuel, and set up for easy cruising.

I was wondering if anyone wanted to see the factory Savana tune file. I also have my current tune file in which Ive made adjustments so it will start and run in my Suburba, and I also ran BC Trans tool on the 6L90. Other than that, I havent touched it.

I have compared the file to a 2012 2500 truck with the 6.0, and oddly enough, many of the timing tables are similar or identical. I think the torque management is probably where things differ. The only issue is in the compare file, lots of those sections are greyed out for the Silverado. I also noticed that PE seems to NEVER come on in the Savana as far as I can tell.... I did mess with turning PE on, but either I wasnt able to get it to come on fully, or I did something else wrong because I couldnt notice any difference.

Lastly...if anyone has any advice for changes to either the engine tune...or even the trans tune...Im all ears. Im not begging for help, mostly just wanted to share the tunes since when I researched there wasnt much info on the 4500 Van engines. My main complaints about the setup is that it shifts into 6th gear when cruising up hills and doesnt want to shift back down without 75% of throttle, then shifts right back up when I let off. It lugs a LOT and that is likely hurting my MPG...which is my only other complaint. 9 mpg avg whether i take it easy, or flog it. Thats telling me there is more in it. Truck weighs 5640 lbs.

Anyway thanks! If you want to see anything logged please let me know! (Yes its name is Bruce...they all need names right?)

The Engine is bone stock internally and only long tubes installed. The trans has a ZIP Kit, upgraded the separator plates, and added a ZL1 converter based on some suggestions.

Justin

1 Bruce Original Read File.hpt

11 Bruce Modified (P0690 Removal).hpt

[NotSure]

BC Trans Tool should have helped significantly. You can fine tune after that, just be sure that you don't overlap any upshift/downshift or tcc apply/release speeds. Be sure that you log the Trans Shift Mode so you know if it is working from the Normal, Pattern A, or Pattern B charts. Did you put in a tow/haul input when you transplanted the powertrain?

Do you want the TCC to apply in lower gears? That is how it is set currently. Some disable TCC completely until at least 5th gear, maybe 6th, for better driveability.

I would also zero out the tcc desired slip, then log tcc apply, tcc slip speed, and tcc pressure to see if crowding the throttle at cruise speed is causing it to slip excessively before it disengages. Bumping up the TCC Regulator Offset, which works as a pressure floor (pressure minimum), can help with slip, but is not a cure for bad apply/release speeds and throttle %.

[Jeepguy25]

Thanks for the reply! Im still pretty new at Autotrans logging/tuning. All my previous swaps were T56....which is cake haha. This is also my first Gen IV so Im still working on what parameters I should be logging for both the engine and trans to provide useful feedback.

I did not put any tow/haul modes in when I transplanted. Right now, I put the shifter in "OD", and that is normal driving. If I move the shifter into "D", it will not shift from 1st, so I think that is probably manual mode...and I dont have a tap shift switch installed yet to mess with it.

I know that I turned off lock up at WOT in most of the gears when I transplanted the BC info. But I guess I dont really need TCC if Im in 2nd or 3rd...or probably even 4th.

Im trying to see if there are some scanner templates that I can use so I can get some logs with relavent information...or Ill just have to keep searching for what I need to be looking at.

Fort he most part it runs and drives nice. Sometimes when I floor it after it shifts to 2nd, it takes a second, and when it hits 1st it almost seems like it hits rev limiter. Its rare. Also...it doesnt seem to drop into 1st until Im basically at a stop. So if Im slowing to make a sharp right hand slightly uphill turn (I know thats specific haha..its on my route home), it will try to be in 2nd, then go down to 1st. Not a huge deal but at 5 mph I would expect it to be in 1st already. Minor issue compared to the lugging up hills.

Thanks for the feedback!

Justin

[kevin87turbot]

It'll make a major difference in performance to simply activate PE Mode.
In order to do that, just change the values in the PE tables to ones that I've shown below.

You can also disable the Traction Control and Wheel Hop Control under the Torque Management tab.

E38 PE Table Mod 1.png

Let me know if you need help turning it up. I do a lot of remote tuning.

Thanks,
Kevin

[Jeepguy25]

It'll make a major difference in performance to simply activate PE Mode.
In order to do that, just change the values in the PE tables to ones that I've shown below.

You can also disable the Traction Control and Wheel Hop Control under the Torque Management tab.

E38 PE Table Mod 1.png

Let me know if you need help turning it up. I do a lot of remote tuning.

Thanks,
Kevin

Ok I will try the PE settings you show. I think I did something similar, but Ill double check my old tune files. I saw a good commanded AFR after turning on PE, but without a wideband I wasnt sure how to verify it was doing anything, and seat of the pants didnt feel much different (not that Im sure it will in this pig haha).

I would love some help! I didnt want to come on begging or expecting any help. I know the basics and know my way around the Gen III stuff enough to stay out of trouble. But torque management is completely foreign to me haha. I didnt see any settings for tracking control or wheel hop but I need to poke around some more.

Thanks!

Justin

EDIT: Looks like I used 1500 rpm and 100% Throttle bypass. I did zero out the delay. I think I maybe messed with the EQ ratio tables to command the AFR I wanted...but Ill try your settings and see how she goes.

One last thing I forgot to mention is mods...engine has long tubes only, and the trans got a ZIP kit and upgraded the separator plates. I also went with a ZL1 torque converter over the stock truck. So it should stall slightly higher (2000 rpm?). Ill add that in my top post.

[NotSure]

Need to log the trans shift mode to see what shift charts it is working from. If you don't plan on having a "tow/haul" mode, you could make them all the same.

Your 2-1 shift on that specific turn is an easy fix, just raise your 2-1 shift at 0% TPS by one mph and try again, might take a couple of mph. Right now, IF you are actually in Normal mode, it is set to NOT downshift until you drop to 6 mph when at 0% throttle.

You have some room to reduce the Shift Timing on your shifts as well. Stock settings are very slow. If you want to quicken the shifts, reduce the numbers in the Torque Adder charts (Upshift and Downshift tabs). CAUTION!! Do not make big changes, maybe 5% at a time, 10% tops, and I would not go lower than the lowest numbers already existing in those charts, about 0.35. If you make changes to the Torque Adder (aka Shift Timing) charts, put some drive time in between changes to allow it to relearn.

Regarding PE, there is a 50 second delay in this cal (Enrichment Timer), you can zero that out. Also the Enrichment Ramp In/Out are set to verrrry slowly ramp in. Maybe raise that to 1.0 as well.

[Chevy305]

To add on what everyone else has said, make sure any time you make changes to shift pressure or shift timing or TCC pressures you need to do a Trans Adapt resets in the scan tool after writing in the changes.

Also for PE, go into the THROTTLE: HOT table and change the RPM Vs Throttle % for enabling PE. I usually set it to 2500rpm and up to enable at 35% throttle.

[Jeepguy25]

Thanks again all. I haven't had a chance to try the changes. Got sick...might be covid 🙄 as soon as I'm well enough to tinker I will and I'll post up how it goes.

Justin