Tuning help on a 2006 8.1

[JD4440]

Where do I even start ??

[Taz]

All L18 8.1 L engines were DBW (drive by wire) and used an LS1-B PCM. Same tuning principles apply for 8.1 L as any other LS1-B equipped vehicle. Check out the AutoVE Tuning Tutorial and the Calc.Ve Tuning Tutorial that would have downloaded with the EFILive software - usually C:\Program Files\EFILive\V7.5\Doc\Tutorials

Regards,
Taz

[JD4440]

Thanks. Thought I might pull out some/ most of the tq mngt and see if it made much difference to begin with. Only thing is I have to run E10 fuel :-(

[Gregs]

yeah ditch the tm. Do you have a wideband? if not you need one.

[JD4440]

Actually I don't. where do you get one ?

[Gregs]

you can get one from just about anywhere, there are lots of options and efilive supports like the top 10 most popular ones. I know there's a guy who sells them wired up for the serial link on the v2 but their name is slipping my mind right now. otherwise its not hard to wire them up yourself for serial

[joecar]

See here: showthread.php?14650-Setting-up-my-LC1-using-a-TAQ-Cable (http://forum.efilive.com/showthread.php?14650-Setting-up-my-LC1-using-a-TAQ-Cable)

[JD4440]

Guess I have some troubleshooting to do first. I can read the TCM but when reading the ECM it stops at getting status. The V2 doesn't light up when plugged into the DLC so I must have a shot fuse somewhere.

[Taz]

I'm a little confused ... 8.1 L could have came with a 4L80E or an Allison transmission ... believe either way there was just a PCM.


Regards,
Taz

[JD4440]

Allison, Has the same TCM as my Duramax.

[Taz]

Interesting ... have a 2004 8.1 L with Allison transmission in my database - looks like PCM controls the engine & transmission. Maybe 2006 were different ...


Regards,
Taz

[ScarabEpic22]

No, Im going to bet that you are correct Taz, 06s should still be running an LS1-B PCM 1MB so both the engine and trans (even an Alli 1000) is the same module. Try reading it out as a LS1-B, that should get you started. If not, come back and we'll try and figure it out.

[Big Mike]

The trucks used the Allison's behind the 8.1 of course, the Avalanches used the 4L80E and BOTH use the LS1-B controller. This is why some of the trans parameters are there in the Allison equipped trucks, because they use the same PCM. So to connect to the engine PCM use the LS1-B option regardless of trans model.

[Taz]

My apologies JD4440 ... had worked on a Suburban with 8.1 L and 4L80E which had a single LS1-B PCM ... checked this morning - Allisons used a separate trans module - as you had stated originally.

That you were able to connect to the trans module and read it, at least lets you know that the tuning "hardware" is working correctly. Never worked on an Allison ... try fresh boot on your laptop ... select LS1-B style PCM .... make sure all power accessories are off .. doors shut ...etc.

Hopefully someone who has worked on an Allison will post up. If the above doesn't work would then try isolating the PCM - pull fuses to BCM, trans module, etc.

Again my apologies for making assumptions earlier ... generally happens when the grumpy old man is tired !

Regards,
Taz

[ScarabEpic22]

Hmmm, so 8.1L + Allison 1000 means LS1-B PCM for engine and an Allison TCM for transmission? I thought the LS1-B took care of it all, interesting.

[JD4440]

Gig lighter fuse was blown. Pulled the tune sucessfully tonight. Lot's of interesting perimeters for a gas motor

[Big Mike]

Was going to mention to check that but since you could read the TCM didn't suspect it as the issue. Good deal though.

I have nearly two years worth of tuning/learning on my 8.1/Allison so if you get stuck somewhere feel free to ask. I'm no whiz by any means but perhaps my 8.1 specific info would be extra helpful.

[JD4440]

There were so many tq reference tables! Do they all have to be modified to remove/lessen tq management ?

[Big Mike]

In the PCM or TCM? I've worked with the TR adjustments greatly in the TCM and never found it to be positively effective, most of the ACTUAL TR is done via the PCM...although it is based on some info it receives from the TCM. In other words, just allow the trans to tell the PCM what to do...but adjust what the PCM actually does with those requests instead. Doing so keeps the trans happier and the shifting better overall.

So that mostly just leaves the PCM for TR adjustments and there's really only one you actually need to work with to find the sweet spot, the rest you can just max out/disable (BTM, max allowed torque, max axle torque etc.). The biggy you want to fine tune and where 95% of how the truck and trans functions is based on the percentages in table B6605 "TCS spark retard torque loss". This is the table that will have the most profound change on how the truck feels and more importantly how the trans acts. If you reduce it greatly or worse yet zero it out completely the trans will begin to shift very harshly. It's tolerable at first (similar to an old school trans w/ a shift kit) but it quickly learns and gets far too harsh since the PCM can't reduce spark on the shifts that the trans is asking for. I stated out with zeroing it out (as you can do on an 01-02 Allison truck) and quickly discovered that it NEEDS some spark retard to work smoothly. So I started over and only removed 50% from the entire table. Worked decent but was still a little too harsh once the trans re-learned the new shift times again. So I ended up at 60% (removed only 40% from stock) and that's were I've had it for over a year and it still works well. I recommend only changing it about 10% at a time as it's rather easy to over shoot the desired results.

For the tables you really only need to max out/disable/zero once, they would be:

B1901- Max Allowed Engine Torque
B6601- Axle Torque Limiting
B0401- BTM Enable RPM
B0402- BTM Disable RPM
B6607- TCS Max Time Allowed
B6609- Tip-In Torque Reduction
B6610- Tip-In Torque Reduction Min Speed
B6614- Max Torque By RPM
D2001- Abuse Mode RPM Enable
D2002- Abuse Mode TPS Enable
D2003- Abuse Mode Speed Enable
D2004- Abuse Mode Torque Reduction

Also, working with B6612 "ETC pedal torque limit reduction" makes a noticeable improvement but you have to be VERY CAREFUL with it as making too great of changes (especially in the lower tables) will cause the throttle to stick open. Not good but it's worth it if done carefully as there's some gains to be had there too.

These will get you started on the preliminary adjustments. Then ditch the PE delay timer and lean out PE some as these 8.1's are PIG RICH while in PE. Then work on timing to reduce any factory KR (they're very KR sensitive). Adjusting Stoich and 02 switch points for the E10 is favorable as well.



For adjustments in the TCM and after many trial and errors I finally settled on only changes to the upshift/downshift speeds and TCC apply/release speeds in an effort to improve the over all response of the truck (to throttle input). But those adjustments would be based on personal preference. I can tell you though keeping the TC released at WOT really helps the engine rev more freely as it's climbing the tach. If you haven't noticed in the factory tune the TC is applied as soon as WOT is entered and it remains locked throughout from there. Allowing it rev easier/quicker by leaving the TC released really makes a positive difference in overall performance when you really plant your foot to the floor.

[JD4440]

Wow, Thanks Mike. I'll make a few minor changes and see what kind of difference I see. I was thinking of using my modded trans tune from my DMax to start and see how it did . I believe the things you stated are all that are changed in it.

[Big Mike]

Sure you can try your Dmax trans tune but I wouldn't expect it to work as good as it could with a gasser, espectially with the TC apply/release settings...the torque and power ranges are just far too different. But at least it will give you something to compare to. Post back as you go as there's not too many of us 8.1 guys so it's nice to confer between the ones that are.

[JD4440]

Havent forgotten about this, been finishing up some things on the other truck. Thanks for the help so far. Chris