Truck falls on face with new turbo

[02dirtymax]

I put a Silver Bullet 66mm on my 02 about a month ago and I have been getting a big defuel or something at around 80-90 mph WOT. I have been running a hefty EFI tune from Fleece on it for about a year and it ran good with the stock turbo, but now that I put the turbo on with the same tune it is falling on it's face in 5th gear. I can e-mail somebody the log or you can see it here, I've never logged my truck before so any comments are appreciated as to how it looks and what my problem might be. I held the throttle while it was doing its "defuel" longer than normal during this run and it threw a P0238 - high boost pressure, that is the first time I have got any codes.

 

[GMC_2002_Dmax]

That overboost codes can cause a mm3 fuel limit.

If you have the tune make sure the Limp Mode fueling is raised.

 

[02dirtymax]

It has done this defueling several times with no codes-and it does it every time, runs plenty good if I'm not WOT in 5th. I only got the overboost code when I held the throttle for several seconds longer than normal. If I run a smaller tune I don't have the defueling problem, it keeps on going until I let out of the throttle. On my smaller tunes I am only seeing around 30# on my gauge, and with the big tune it is at 40-45# before it falls on its face and sends me through the windshield. Somebody mentioned boost scaling a while back, does anybody know anything about that? I think limp mode fueling is raised, I'll have to check when I get home. In the log when boost pressure reads 46# the desired fuel pressure drops so that makes me think it is a defuel and not just me running out of fuel correct? I saw that I am holding 22K on a long run with 26K desired, is that decent for an LB7?

 

[GMC_2002_Dmax]

If the rail psi is holding watch the MM3 and the PW, see if they change.

If you holding say 100mm3 and 3000us and the log then shows 40mm3 or the pw drops to 1400us then you will see that in the log.

Did you raise your speed limiter ?????

 

[02dirtymax]

I stopped the problem, but don't know if it was the right way..... I studied the log some more (I've never looked at one before) and around frame 40 I am running 3400rpm and go from 3200uS and around 120mm3 to 800uS and 50mm3 instantly. So that tells me something told it to limit itself to 50mm3, I studied all of the fuel limiting tables for around 3400rpms and I found B0733 engine protection stg 1 does exactly that. I raised the whole table to 100mm3 and my problem is fixed. I dont' know if it is a good idea to raise that table, I don't know if there is a good reason for it to go into that protection mode or if it is just because of the boost.

 

[02dirtymax]

Brayden fixed the tune up for me, it was boost DTC's. He took care of a few other things while he was at it also.

 

[LLY]

sweet,lets see a video of how this thing runs :happy2:

 

[02dirtymax]

I don't know if my camera can handle the G-forces, we'll see what I can do.

 

[Brayden]

Glad you like it

 

[racinmike77]

Sounds like the same gremlin I have, im running the stock turbo though and the truck falls on its face in fifth gear about 95mph. Its not the limiter I have it set at 120. Just curious where do you recommend I log at 90mph for a couple seconds? Highway? :spit:

 

[Mike_S]

Sounds like the same gremlin I have, im running the stock turbo though and the truck falls on its face in fifth gear about 95mph. Its not the limiter I have it set at 120. Just curious where do you recommend I log at 90mph for a couple seconds? Highway? :spit:

Check and make sure you are fueling high enough in the RPM range to support that speed...

 

[racinmike77]

95mph in 5th is around 2800

 

[Mike_S]

torque limiting tables, torque limited injection quantity, these could also be culprits. No codes? what is your boost pressure at? could the desired boost table have been changed by mistake?

 

[Operator1]

Sounds like the same gremlin I have, im running the stock turbo though and the truck falls on its face in fifth gear about 95mph. Its not the limiter I have it set at 120. Just curious where do you recommend I log at 90mph for a couple seconds? Highway? :spit:

C1801, C1802, C1807 & C1809 were what I raised to solve this problem. Also raised C0804 & C0805 for the same reason.

 

[Mike_S]

Sounds like the same gremlin I have, im running the stock turbo though and the truck falls on its face in fifth gear about 95mph. Its not the limiter I have it set at 120. Just curious where do you recommend I log at 90mph for a couple seconds? Highway? :spit:

It would also help us out alot if you would list your mods in your sinature. are you running with a boost valve or aftermarket wastegate?

 

[racinmike77]

I have a tough tranny a stock spinny thingy and some computer laptop thingy called V2 which I actually have tuned 4 trucks with.

 

[racinmike77]

C1801, C1802, C1807 & C1809 were what I raised to solve this problem. Also raised C0804 & C0805 for the same reason.

Thank you, I only went fast enough once last week to notice it, ill try to log and fix it this weekend.:hug:

 

[sweetdiesel]

Sounds like the same gremlin I have, im running the stock turbo though and the truck falls on its face in fifth gear about 95mph. Its not the limiter I have it set at 120. Just curious where do you recommend I log at 90mph for a couple seconds? Highway? :spit:

why not just log a pass from 0-100mph?

that will show you when/where you are loosing fuel

 

[02dirtymax]

why not just log a pass from 0-100mph?

that will show you when/where you are loosing fuel

X2, find a nice test area (stretch of road that is free of cops), start a log and put it to the floor up until you feel the problem and make sure you hold it for a while while the problem is happening and then go back and check the log. If rail pressure and pulsewidth fall back slowly you are running out of fuel. If something drastic happens such as in my case instantly going from 120mm3 to 50mm3 and cutting my pulse width from 3200 to 800 then you have a defuel that is caused by the truck limiting itself. By the way, a defuel like I had feels like it is going to put you through the windshield when it happens at 90mph.

 

[JoshH]

I have a tough tranny a stock spinny thingy and some computer laptop thingy called V2 which I actually have tuned 4 trucks with.

Did you sell that $150 exhaust for $500 yet?

So I guess you're an expert and can figure it out on your own, seeing as how you have tune 4 trucks and all...