LBZ: Fuel issue, possible cp3? [Archive] - Duramax Diesels Forum


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09-15-2011, 02:57 PM
I'll try to make this as clear as possible. I'm trying to get a list of things to check to help solve my issue.

I have a 06 LBZ, efi live idaho rob dsp5 tune, turbo back exhaust, ppe intake mod, ppe lift pump, ppe stage 5 tranny with ML converter, race valve. those are the things done that should pertain to my issue.

I ran the 1/4 mile sunday for the first time. I know that this tune should run fairly clean but the truck only puffs a little smoke off the line and then basically did not smoke the whole way down the track. Also a very similar truck that has all the same basic stuff done ran a 12.8 last year and the best i could do all day was a 13.134 @ 103. 60' was 1.9xx All this being said I think I'm lacking fuel.

Yesturday I took the day off from work to mess with it some.

I was running my pump @ 12psi @ an idle. It was dropping near 6-7lbs @ WOT, so I turned it up to 14lbs @ idle to get 8psi @ WOT. It does not lope or surge at an idle.

The fuel filter is fairly new and the in dash display reads 75% filter life left.

I have not made it to my tuner's house to check the balance rates of the injectors or the acctual vs. demanded pressure.

Any ideas on what else to check?

Thank you in advance, need to get this right so I can dyno on Saturday.

09-15-2011, 03:12 PM
As you'll see in my sig I used to run Josh H's race tune that he had posted on here, after I ran 13.3's and a best fo 13.2 i had my tuner load Josh H's tune back in and made my 13.13 run. So currently that's the tune I have in. and I'm see about 31-33lbs of peak boost, settles in around 30-31.

09-15-2011, 03:31 PM
what was your 60'

09-15-2011, 03:44 PM
60' was 1.9xx

09-15-2011, 03:54 PM
Your lift pump looks to be about right at wot pressure so i wouldnt think thats the problem. Now the truck that ran the 12.8 was it lighter than yours or about the same weight. When you say clean do u mean no smoke at all or a slight haze?

09-15-2011, 03:57 PM
I'm heading to Craig's (maine04max) to hook it to EFI and check injector rates and rail pressure now, ill update what we find.

blk smoke lb7
09-15-2011, 04:12 PM
That stupid thing in the dash that tells you you have 75% filter life plans on you driving normal in city and highway traffic or working at the farm,It wasnt made aware or your lift pump tuning and fuel requirements so if you could throw it out the window i would.My guess is the fprv is letting a little more fuel back to the tank then it should but your comanded and delivered will help show that i am hoping,otherwise do the bottle test to be sure

09-15-2011, 04:30 PM
First I would do some logging before you get too worried. Good tunes should clean up well with a stock turbo. If your holding rail pressure I wouldn't get too worked up. Work on that 60 ft cause every tenth in your 60 is good for 2 tenths on your et. If your not holding rail start small with fuel filter and do a bottle test. Then if all that is good do a return rate test on your injectors.

09-15-2011, 05:44 PM
i think some more tuning refinement and better 60 will net what you expect

09-15-2011, 06:27 PM
A bottle test will be getting done tomorrow . the logs do show a loss in rail pressure

09-16-2011, 03:44 AM
Update. Went to Craig's and logged like he posted, he also told me my dsp5 tune wasn't and Idaho Rob tune. Oh well, guess I'll be shelling out some dough to him to get one next paycheck.

Log showed acctual pressure around 21-23k while desired was near 27k. Also tried the Josh H race tune and the desired was 26k and was running around 25k.

I will bottle test tonight. In the event that passes I'll try changing the filter, its only been in the truck a month @ the most, but who knows maybee I got a bad batch of fuel.

If that doesn't fix it I'll be looking into cp3 options........ this one has 134,000mi on it, and they been hard ones since 63k when i got the truck.

Also in response to it being the fprv, it has a race valve installed.

Thanks for all the help.