2007 LBZ tune

[MikeOD]

I've been working on this tune with a friend of mine, his truck is a 2007 Silverado Classic quad cab dually. As far as I know the only mods to the truck are an MBRP exhaust and our tuning. I've tuned a lot of gasoline vehicles, as has he, but this is our first experience with a diesel engine other than using hand held tuners to flash trucks.

The truck drives great with this tune, for the first few days after I flash it in, but then it slowly gets crappier and crappier, throttle response goes away, and the truck feels like it's loading up instead of downshifting.

We're thinking that the TCM is probably doing some learning, and we need to learn what to do with the commanded shift points in order for the learning to work with the engine tune instead of seemingly against it.

The only other thought we had, is EGR. He had asked me to disable EGR, which I initially did, but last night while playing with it, someone else mentioned "until you block the EGR off, leave it enabled". I didn't realize it wasn't blocked off, so I turned it back on last night. If the truck doesn't progressively change (for the worse) as it did the past few days before turning the EGR back on in the computer, I'll be thrilled, but I am not confident in that, and I think we'll be learning more about the transmission calibration in the near future.

The EGT does get up there when he lets the truck have it, I added some fuel to the base fuel quantity table and that seems to have gotten better, it takes longer to get hot, but still gets hot enough to make me nervous. Previously it would spike over 1400 degrees fairly quickly, now it takes quite a bit of time to get up over 1400...but I'd like to keep it well below that if possible. What else can I do to combat EGT? Less boost? Would more fuel under high boost help lower EGT without dropping power significantly? The truck has fantastic power right now, but if giving up 20 horsepower means significantly lower EGT's, I think thats probably a good thing. The truck has no "timing rattle" at all, and right after a flash pulls very strong and very smooth. Shifting right after a re-flash is great as well.

[MikeOD]

I also wanted to ask about the variable vanes on the turbo.

The vane position max is never higher than 85% in the high range and 80% in the medium range and 90% when in the cold range, even though the max possible value in the table is apparently 200% according to HPTuners.

Is 90% mechanically as far as they can go? If not, could opening them further help with EGT and/or power? If I understand them correctly, it should help reduce back pressure, and drop EGT.

[mecanicman]

You have to think about a Diesel opposite to a gas engine when it comes to boost. More boost will cool your egt. Adding more fuel is what is making your egt go up. Play with injection timing or command more boost or reduce fuel to lower egt.
The transmission adaptive memory is cleared every time you flash, and then learns as you drive. Under Engine-Torque Management-Engine-driver demand and peak torque you have not made any changes. Based off your description and my quick look through your tune, these tables will need modification.
I am not sure as to max actual vane position, i have not deviated greatly from stock.

[MikeOD]

Thanks for the help. I'm going to try bumping timing a little but at light load to bring MPG up, which will probably also bring EGT up, but I guess if I pull it back under higher load/boost, I should be able to control it better.

I'll also start making changes to the driver demand and peak torque tables to see what I can achieve.

[mecanicman]

a 50/50 timing setup will work nicely for you. Do a search in this section under my name, I have posted a calculator. This will work better then you bumping it in spots.

[MikeOD]

Awesome, I wasn't going to go at it blindly...but not starting from scratch is way better than figuring out a calculator myself...especially since I don't yet know what I want to calculate lol.

[MikeOD]

Here's the newest version of whats in the truck. It feels very very powerful, and the EGT does stay more in check...I wouldn't call the EGT great, it still gets hot, and I also wouldn't tow anything with this...at least not yet.

I'm still working on this though, we agreed he needs to drive it for a few days to see if the TCM is still working against us when it learns or if I've got a better handle on that, and I also want to see what his MPG does.

When he punches it from a stop, all 4 back tires start to spin, then it feels like the truck loses power, then comes right back...if it manages to get traction, that doesn't happen. Where would I look in the tune for that?

[mecanicman]

Sounds like your torque management may still need some tweaking. Just keep in mind the more tm you pull the harder you are on the trans. Only try the following at your own risk and if you are comfortable with the concept. It is easy to kill the trans playing with these. If you play with adaptive preasure offgoing and clutch volume preset you can make the trans shift a little faster. Problem is if you get to carried away in combination with shift times you will be in 2 gears at once and it wont last long.
Have you tried logging anything? watching your boost? Looks to me like you could be commanding more to keep you egt's down. I did not see anything specificly wrong in your tune, looks good.

[MikeOD]

I have so much trouble getting the scanner to log anything at all...we have tried, but I can't reliably get anything to log. I updated to the newest beta last week but that didn't seem to help that communication...I kinda hate tuning like this...I wouldn't call it blindly, but it's like I don't have my glasses on.

Our next step will be just what you said about commanding a little more boost as RPM climbs to see if we can bring the EGT down some more...I'm also going to play with that timing calculator a bit more on the top end. He doesn't necessarily want the most power possible from the truck...but right now it feels as fast as the craziest tune in his hand held felt, with better EGT and no timing rattle...

I think he's planning on a stronger converter and a trans rebuild to handle more abuse in the near future, after that we'll probably be more willing to play with the trans settings.

Far as I know though, this most recent tune is doing a lot better...just in time for me to put my head back around gasoline engines with the 2010 Camaro SS I just bought myself

[MikeOD]

Here's the most recent revision of the tune I have in his truck. Commanding some more boost, played with timing a little, and played with the torque settings a bit as well. It's got some soot to it, but not bad, lots of power, and EGT seems reasonable.

[ajamesbond007]

I have a question. On your desired boost tables, did you switch the low and high tables? seems like in the low baro, you are going to command around 3-4 pounds of boost at idle, and in the high baro, you dont start producing boost until 1600 rpms and 40 mm^3 of fuel. Just curious as to why you set it up that way

[MikeOD]

Looks like I made a mistake that I need to fix. Thank you for pointing that out.

[ajamesbond007]

Hopefully that will help with your soot problem. Let us know

[bmftransam]

im no pro at tuning but i know when i was running the diablo 120hp program it would do the exact same thing and then it would throw me into safe mode with fuel rail pressure too low, so imho it might be something to look into with fuel rail pressure