Turbo Brake Function?

[KB3MMX]

Hello, I wrote a tune for the Turbo Brake function to use 95% vane postition from 1200rpm->the end of the rpm map while at 0mm3 fuel command on Low,medium,high Altittude maps for Max vane position and Desired Vane position.:cucumber:
I am wondering if I need to do anything on the tables for Low,Medium and High altitude Desired boost?:nixweiss:

Thanks !!!

[JoshH]

You should raise it to something pretty high (30 psi should do the trick). The only thing you might want to do is raise the underboost error time so you don't throw an underboost code while in trans brake mode. You may also want to raise the minimum vane position in the same areas you raised the max and desired.

[Dmaxink]

just my .02...setting it at 1200rpm is slightly low, as in with normal driving, anytime you come off the pedal it will start its "backpressure" and it will get annoying as hell. I set all my from around 2100 on up.. T/H engaged or not it will be in a constant frenzy anytime you come off the throttle... but thats just me.

[JoshH]

just my .02...setting it at 1200rpm is slightly low, as in with normal driving, anytime you come off the pedal it will start its "backpressure" and it will get annoying as hell. I set all my from around 2100 on up.. T/H engaged or not it will be in a constant frenzy anytime you come off the throttle... but thats just me.This is true. I set mine at 1800. Never have a problem with it engaging unless I'm going over 80 or it's in T/H mode.

[bballer182]

Josh. You know the boost table is ignored at zero mm3, right?

Sent from my ROM'd and 1.3 GHz OC'd Samsung Captivate

[JoshH]

No, never really payed much attention to it.

[bballer182]

No, never really payed much attention to it.

as defined in B2231 and B2232.

[KB3MMX]

Josh. You know the boost table is ignored at zero mm3, right?

Sent from my ROM'd and 1.3 GHz OC'd Samsung Captivate

Good info !!!!


just my .02...setting it at 1200rpm is slightly low, as in with normal driving, anytime you come off the pedal it will start its "backpressure" and it will get annoying as hell. I set all my from around 2100 on up.. T/H engaged or not it will be in a constant frenzy anytime you come off the throttle... but thats just me.

I have a trans tune that keeps the TC locked at anything above 22Mph with reshaped shift curves, so that's not really a issue so far.....actually makes it kinda sweet to drive.:good::good:

[dansdieselp]

I've had two LBZs now that will not follow my commanded vane position no matter what I do. Command is 100% at 0-5mm3 and 34psi boost. Also changed B2231 and B2232 to always enable boost control. Doesn't do what the tune calls for and vane position isn't as steady. Both trucks have the 6128 op system.

[cook]

when my truck is at idle it runs 10 to 11 mm3 so i set the tables from 0 to 15 mm3 from 1600 rpm on up, vane position 100 and boost 58 works perfect

[bballer182]

I've had two LBZs now that will not follow my commanded vane position no matter what I do. Command is 100% at 0-5mm3 and 34psi boost. Also changed B2231 and B2232 to always enable boost control. Doesn't do what the tune calls for and vane position isn't as steady. Both trucks have the 6128 op system.

Dan-
you shouldn't have to change 2231 or 2232. factory setting is ok for turbo brake. I have asked Ross once before to edit the table descriptions. They are a little confusing. The end result should be that the ECM will NOT try to control boost, (ignoring the boost table) and referencing the vane table only.

Did you edit the max vane table too by chance!

[dansdieselp]

I'll try upping it a little on the next truck and see if that works. Thanks for your input.

[Boost]

Are the vanes strong enough to turbo brake the truck? Silly question but I am picturing a small turbo slowing down a huge truck... the idea is strange to me at first. Also, is there any undesired effect say in heat buildup due to the backpressure? I ask because I increased idle vane position on an LBZ for better response and desired sound. Thanks.

[bballer182]

Are the vanes strong enough to turbo brake the truck? Silly question but I am picturing a small turbo slowing down a huge truck... the idea is strange to me at first. Also, is there any undesired effect say in heat buildup due to the backpressure? I ask because I increased idle vane position on an LBZ for better response and desired sound. Thanks.

There is no ill affect. It is a factory tuned feature on the medium duty kodiaks and topkicks.

Sent from my OC'd Samsung Captivate

[Boost]

Thanks!

[Boost]

So I'm wondering, why are there J-brakes available that go in the downpipe, are they stronger? And the last of the "4500"s they were LLYs right? Not much use looking at their factory turbo brake parameters when setting up an LMM to tow a motor home and use the turbo brake?

[bballer182]

The exhaust brakes that were the flapper valves were use up to '06 (true LLY's) the '06 model year MDs actually had LBZs in them but detuned and re-RPO'd for the MD's as LLYs and they use toggle switch to flip the ECM into a separate set of tables that was never released to us. And same goes for the LMM MD's. So there are no parameter for you to even look at to see what they were doing. Sorry man.

[dansdieselp]

Tried another LBZ and same result. No turbo brake or open vanes at idle. Can't figure it out.

[bballer182]

Tried another LBZ and same result. No turbo brake or open vanes at idle. Can't figure it out.

If you want Dan, you can e-mail me the tune and I can see if i can find any reason why it would be working...

Justins@molalla.net

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[Drake_Lawdawg]

I know this is an old thread, but how do you get the vanes to only do this while operating in T/H mode? On the LMM it looks easy but the LBZ I can't find a way???

[bballer182]

I know this is an old thread, but how do you get the vanes to only do this while operating in T/H mode? On the LMM it looks easy but the LBZ I can't find a way???

LBZ is identical to the LMM with respect to turbo brake tuning. Also, there is no way to turn it on ONLY while in T/H, however, there is a way to cheese it. Under normal driving conditions (cruise braking) the engine typically won't go above ~2000-2100rpm so you can close the vanes down in 0-5mm3 and above 2000rpm and without T/H the turbo won't close down.

[Drake_Lawdawg]

After pouring over this some more there looks to be a way to do it through the TCM as well. It would technically be on all the time at 0% throttle input but you would only "feel" it when the TC is locked.

[bballer182]

After pouring over this some more there looks to be a way to do it through the TCM as well. It would technically be on all the time at 0% throttle input but you would only "feel" it when the TC is locked.

The only way to engage the turbine brake is through the engine tune. And, yes you are correct the only way you'll feel the brake is with the converter locked.

[killerbee]

Are the vanes strong enough to turbo brake the truck? Silly question but I am picturing a small turbo slowing down a huge truck... the idea is strange to me at first. Also, is there any undesired effect say in heat buildup due to the backpressure? I ask because I increased idle vane position on an LBZ for better response and desired sound. Thanks.

Given that "no-fuel" exhaust is not capable of much more than 10-15 psi of boost at 4000 engine rpm, the turbo shaft is only exposed to something like 50HP max of power, which is transferred to the wheels for braking if the TC is locked. IIRC, the shaft is good for at least 250HP before snapping (albeit at 20,000 rpm).

In reference to the other concern about having an unlocked TC at high rpm, if you do this with hard turbo brake in T/H mode, your tranny will toast pretty quickly in theory on a 10 mile grade. Serious viscous slip heat.

[garrettg.bpd]

Has anyone had turbo braking just stop working? but still build normal boost levels when not braking.

[bballer182]

Converter unlock or something? Some parameter wasn't met and the vanes opened up. Its in the program. Best thing to do is log

[Boost]

It is most likely something goofy or inconsistent that I am doing, but it seems to me that known good turbo brake settings only work on 50% of my trucks. :nixweiss: I know for instance that some OS do not have certain transient tables that affect this, and also that it only kicks in when specific conditions are met but - on some trucks it works great and is easy to notice it yet others in never works or only once in a blue moon... haven't quite figured this out yet.

[garrettg.bpd]

Dose any know what are the best duramax OS are.

[bballer182]

I don't have it in front of me but the second from the latest is the one I prefer. For LBZ, that is. The last OS that was made for the LBZ was rumored to have tune tracking so I passed on the "update."