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Duramax 6600 Discussion Forum for the Duramax 6600 Diesel Engine, including the LB7, LLY, LBZ & LMM engine specific topics.

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  #1  
Old 02-03-2010, 09:02 PM
gtrtech gtrtech is offline
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Question 2004 Chevy 6.6 Diesel Surge at Idle.

I have a 2004 Chevy Duramax 6.6 that has developed at surge at idle. started very light but I currently get a constant surge of approx. 200 rpms about every 3 to 4 seconds. No surge on cold start, but once it warms to operating temp. the surge begins. Can be felt slightly while driving. Just replaced the fuel pressure sensor on fuel rail and same thing. I could monitor FP on my snapon modis and can see fuel pressure increase at the same time it surges. Any Ideas anyone.
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Old 02-04-2010, 10:24 AM
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THEFERMANATOR THEFERMANATOR is offline
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Most likely it is the fuel pressure regulator valve that is in the CP3 that is the culprit. The LB7 model was prone to spring failures and would cause this rapid fluctuation fuel pressure which results in the idle lope. It's a pretty common issue actually for the LB7.
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1995 GMC 2500 SUBURBAN powered by 01 DURAMAX/ALLISON, 3.42 gears, 261 T-case
Trans has a mild build with ALOT of help from MIKE L. which included ALTO's for C1-C4 and a PI ML converter
DIAMONDEYE 4" exhaust with a CORSA muffler, AFE stage 1 dry filter, EFILIVE, KENNEDY single pump and pump rub kit.
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Old 02-04-2010, 01:46 PM
kaylabryn kaylabryn is offline
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I started a regiment of 2 stroke and mine cleared right up and oinly rears its head if I forget to add any oil for a couple tanks. I have over 20,000 miles since it started loping. Truck has 210,000 miles. Iuse around 1/2oz per gal of diesel.

Mike
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1995 Suburban K2500 6.5TD 3.73's Innercooled, Updated cooling, Banks 3" exhaust no gizzards in the kittie. Pyro/Boost/Trans temp. Transgo HD valvebody kit.
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Old 02-10-2010, 01:26 PM
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Dinkie Diesel Dinkie Diesel is offline
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Quote:
Originally Posted by kaylabryn View Post
I started a regiment of 2 stroke and mine cleared right up and oinly rears its head if I forget to add any oil for a couple tanks. I have over 20,000 miles since it started loping. Truck has 210,000 miles. Iuse around 1/2oz per gal of diesel.

Mike
I searched for my problem here before posting. I know I read somewhere years ago about one particular type of surge being related to fuel pressure and another said something about programming. Mine idles fine and then suddenly it will blip as though you slightly bumped the throttle. You can feel it jump slightly when it's in gear. I tried your 2-stroke oil trick and a healthy dose of fuel cleaner/stabilizer a while ago and it ran perfect for that tank. Now it's getting worse. Thought I should check in here before I spend money needlessly. Thoughts?
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Old 02-10-2010, 02:38 PM
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The FPR (Fuel Pressure Regulator) can be replaced independently of the high pressure pump. My 2001 LB7 has a slight idle surge at times. It's not bad enough to warrant new parts, but maybe someday.....

Jim
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Old 02-10-2010, 03:30 PM
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Every LB7 I owned eventually developed this 'lope'.

Not worth the ~$800 to fix it, IMO.
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Old 02-10-2010, 09:36 PM
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Quote:
Originally Posted by Mark Rinker View Post
Every LB7 I owned eventually developed this 'lope'.

Not worth the ~$800 to fix it, IMO.
I spent $204 for a brand new BOSCH FPR delivered to my door, and I changed it while I had the engine down for headgaskets. Most people with a good assortment of tools and print outs should be able to do one in less than a day.
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1995 GMC 2500 SUBURBAN powered by 01 DURAMAX/ALLISON, 3.42 gears, 261 T-case
Trans has a mild build with ALOT of help from MIKE L. which included ALTO's for C1-C4 and a PI ML converter
DIAMONDEYE 4" exhaust with a CORSA muffler, AFE stage 1 dry filter, EFILIVE, KENNEDY single pump and pump rub kit.
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  #8  
Old 02-16-2010, 10:57 AM
lalou lalou is offline
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Default just bough sierra 2004 duramax 6.6 lly

have same problem at idle . idle ok for 4 sec. then peaks 200rpm for 1sec. somebody have the solution ??
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Old 02-16-2010, 08:13 PM
Grayfox Grayfox is offline
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If you search this sight I think you'll find a service bulletin related to this problem. I had my 05 fixed @ nchg by the dealer. Again it seem seems like there is a service bulletin... check it out.
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  #10  
Old 07-24-2010, 04:38 AM
lalou lalou is offline
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Default idle surge repair

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Originally Posted by lalou View Post
have same problem at idle . idle ok for 4 sec. then peaks 200rpm for 1sec. somebody have the solution ??
went to dealer they change injector harness 700$ nochange still surging did all kind of scroll test then decided to change the FUEL REGULATOR 1000$ AND IT RUN VERY GOOD NOW !!
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