I noticed the tables say "maximum desired boost" and "desired vane position", etc. I'm trying to limit my boost to 32 psi for the stock turbo. I removed the cat today and I can no longer limit boost. I'm seeing as high as 38 psi (365 kpa) and not just for a second. It sits at 35-38 psi throughout a run.
I've lowered max desired to 300, changed vane position around, reduced the boost tables (all of them) and nothing stops the higher boost, doesn't even seem to make a difference.
What am I missing? It feels much stronger with this extra boost and datalogs noticeably quicker from 40-60 mph, 60-90 mph, any increment you choose. I just don't want to hurt the motor or kill the turbo, plus I've been told it will be quicker at 32 psi than any higher psi (so far that is not true in my datalogging, but I can't get a true apples-to-apples comparison until the boost gets back to 32 psi).
It was no problem regulating 32 psi with the cat.
Jody

Cant help really Jody, but that sure does seem to show the restriction of your cat! Did you add a front pipe to your MBRP system?

Cant help really Jody, but that sure does seem to show the restriction of your cat! Did you add a front pipe to your MBRP system?

well sorta. I actually had purchased a cat-back for an 06 but that's a slip on cat vs 4 bolt for mine. So I ordered a front pipe for an 06 and swapped the whole thing over.

Weird though, as with gas blowers it usually will drop boost when you uncork an exhaust.

Jody

these are so clogged that the free flowing exhaust actually requires less energy to make boost.

Did you mod the low altitude table? The stock tables are way high after removing exhaust on the LMM.

Did you mod the low altitude table? The stock tables are way high after removing exhaust on the LMM.

low altitude max vane tables?

Jody

38psi = 265kPa according to the nerds at Cornell: http://www-users.med.cornell.edu/~spon/picu/calc/pressure.htm

38psi = 265kPa according to the nerds at Cornell: http://www-users.med.cornell.edu/~spon/picu/calc/pressure.htm

I'm seeing 365 kpa, but that's total, so you have to minus atmospheric (100 KPA), so your numbers are correct as absolute pressure.

By the way, my son will be one of those nerds next year, he just got his acceptance. :ro)

Jody

Sounds like you need to do some logging so you can then see what cells are being referenced.

I use the word "nerd" out of jealousy. I lacked the ambition necessary to go to a decent school. Congrats to your boy.

Sounds like you need to do some logging so you can then see what cells are being referenced.

I use the word "nerd" out of jealousy. I lacked the ambition necessary to go to a decent school. Congrats to your boy.


Oh, I didn't take it as a slam at all, just proud of my son and what he's accomplished. They are nerds................. :D

I'm logging everything I can think of, and am now playing with the vane positions. Desired boost sits at 331 (32 psi) and I can tell the vane where I "desire" it to be, or give it a "target" position, but there isn't a vane limiter table in the LMM's, at least not in EFI Live. So I'll keep playing with the vanes and see what helps.

Jody

jody what are you using to log boost ?

jody what are you using to log boost ?

gm map2, which also exactly matches what my boost gauge says.

Jody

Possibly a noob question, but: What's gm map2?

Possibly a noob question, but: What's gm map2?

gmmap2 is the total pressure in kpa for the intake. You have to deduct 100kpa for atmospheric pressure from whatever it reads.

Jody

so that's the scantool's name for the boost gauge?


Sorry, I don't have EFI....yet. :D

so that's the scantool's name for the boost gauge?


Sorry, I don't have EFI....yet. :D


I think I have a prescription for that ;)

Get your site unblocked by corporate America's "sex" filter and your business might skyrocket!

I'll PM you.

We now return you to your regularly scheduled boost discussion.

Jody,

I would try tapering the vane percentage down significantly on the big end in tables B2214, B2224, and B2225. This should direct and allow the truck to open the vanes assuming it has met it's target boost pressure.

I'm really curious to see what kind of boost this thing will make with the vanes open (0%), or what exactly is going on. Post up a log screen shot if you get time.


Nick


...damn that sex filter, takes all the fun out of work. :)

This is one of my weird high boost experiences.

On one of my tunes at WOT I hit 40psi of boost with a commanded value of 32psi. I dropped the max vane position by 1-2% in the area this occurred (I was logging data at the time) and everything was OK after that.

This is one of my weird high boost experiences.

On one of my tunes at WOT I hit 40psi of boost with a commanded value of 32psi. I dropped the max vane position by 1-2% in the area this occurred (I was logging data at the time) and everything was OK after that.

that's what I'm playing with now, and it is making a difference. Trying to sneak up on it.

Jody

that's what I'm playing with now, and it is making a difference. Trying to sneak up on it.

Jody
Wouldnt modifying max vane postion inhibit boost building at lower boost levels since at lower boost levels you are going to have a more aggressive angle on the vanes as the boost builds the vanes will straighten out to net your desired max kpa value.

Wouldnt modifying max vane postion inhibit boost building at lower boost levels since at lower boost levels you are going to have a more aggressive angle on the vanes as the boost builds the vanes will straighten out to net your desired max kpa value.
That's the theory but sometimes a little tweaking is necessary.

Wouldnt modifying max vane postion inhibit boost building at lower boost levels since at lower boost levels you are going to have a more aggressive angle on the vanes as the boost builds the vanes will straighten out to net your desired max kpa value.

I was only changing the wot area, and small changes. It's a balance between that and the minimum vane angle as I found out. Raising minimum seems to give more boost everywhere.

I max at about 34, but builds to there from 32. I'm pretty happy where it's at right now.

Jody

So it seems limiting total movement is the quick solution but not the "correct" fix. I cant wait to get my diesel so I can start playing, sounds like there are alot more tables to adjust then on the gassers. Should be fun:)

So it seems limiting total movement is the quick solution but not the "correct" fix. I cant wait to get my diesel so I can start playing, sounds like there are alot more tables to adjust then on the gassers. Should be fun:)
Not every truck engine reacts the same and not every custom tune is done the same way. You only may need to change the vane positions by 1 to 2 %. It doesn't take much.