LB7 power & mileage loss

[duraace9sp]

ok----have had the 01 duramax since late 2000. it got an entire new motor at 55000 miles---now has 105000 miles.......

at 98000 miles i brought it to the dealership for a before warranty expires "going over" and somewhat expecting that my fuel pump was faulty.
I did have a 2 micron racor after market secondary fuel filter installed
(which had proved very effective-each time i changed them both and both the stocker and secondary filters were equally dirty---and my injectors were all in spec )
--which the dealer made me remove before they would look at it (parkway GMC in california)

--anyway---while it was there they said the fuel pump was fine----but i had developed a tranny line leak----i said ok please fix it: 350.00

i went to pick it upfew days later--and tranny fluid was pouring out---i pointed this out to the service writer : who said it was likely residual oil from the repaired leak. however by the time i got home it had dumped 4 quarts of TF.
i brought it back---now they tell me the tranny cooler needs replacement......400.00 more---

3 days later i gat a call the say they havent even started because the power steering pump was bad!!!!

so i say ok i need the %$@^%$ truck fix it!!!

i go there to get it days later---with a list of charges totalling 1300.00. i ask for my old steering pump---they dont have it!!!
i drive home--the new pump is way worse than the old one---wont turn the wheels when idle is low.

BUT|---here is my MAIN complaint/problem------major loss of power----fuel mileage went from 18.5 mpg to 14 mpg----and there is a knocking.

dealer wont do a thing as i am now outta warranty!!!!!

...so i guess id like to find the mileage and power loss----but how?????

[ 01-16-2005, 09:25 PM: Message edited by: duraace9sp ]

[Tough Guy]

You need to go to a good dealer...that one is ripping you off.

Sounds like injectors...can you pull any codes?


Cheers,

The "Boy" TG ;)

[duraace9sp]

i agree the dealer/stealer is displaying less than credible behavior!!!!
....but what really sucks is the loss of power and mileage immediately upon recipt of my truck.
...if it was injectors---it would have been a gradual change not the sudden dump i am experiencing!!!

i log my mileage almost every singel tank/fill----and the change was literally from 18.5 to 14---i thought maybe me----but now five or six tanks---all around 14 mpg-----which of course reinforces my unprovable suspicion that i also have power loss........

...dont know what to do here...

[More Power]

Sorta reminds me of an owner report I received in the '90's where a member took his Suburban to a dealership to have a valve cover re-sealed.

After weeks and weeks, he got his diesel Sub back with 2 new pistons, 8 new glow plugs, a new fuel injection pump, a new starter, 2 new batteries, a new transmission and many other items.... All to have a leaky valve cover re-sealed. :rolleyes:

The final cost was settled in arbitration.


MP

[duraace9sp]

well---2 more tanks gone
14.1 and 15.2 mpg totally trying to absolutely milk the mileage.....
before just drive and 18+ mpg----without a care!!

stealer states all they did was charge me 3 tons of money and change the air filter and mass air flow sensor.....and of course removed the amsoil filter....

stumped and not thrilled!!!

[Dragsled]

power loss..

milage loss...

oh my !

sounds just like my post "Houston, we have a problem".

after taking my 01 dmax to the dealer at 75k miles with a leaking head gasket (leaking combustion pressure into the coolant system) the truck has gone from 19mpg to 15. It takes 1/2 mile, yes a HALF MILE to go from 0 to 70mph. Towing a 4500lb trailer on level roads causes the truck to shift down to 4thgear and run at redline.

The dealer is relacing the injectors next week but i'm very skeptical that it will be any different. No SES light, no tech II error codes. by all diagnostic tools, the engine appears "ok" but real world, its got a major problem and nobody has a clue what it is.

[duraace9sp]

hmmmmm-----
tho i don think its a head gasket---runs smooth/no coolant in oil---the fustrating thing was tues 18.3 mpg and good wed 14 and gutless---

---the stealer did change the mass air flow sensor---and claims not to hav ereflashed!!!
could a faulty sensor do this???

[madmatt]

call your area GM rep and tell him exactly what you told us...then find another dealer.

[duraace9sp]

went to the dealer today----didnt talk to the service writer---went to the back and talked to their fleet/diesel guy----explained everything---was given a bit of info as follows:
complaints of bad mileage or sudden drop in mileage are not "investigatable" by mechanics.
complaints of loss of power without codes are not able to be acted on (at least on warranty)

then bad experiences with the dealer means they are even more defensive and any services will be much worse the next time.....

...he suggested i wait till its blowing smoke or throws codes then take it to another dealer than parkway gmc.....
oh well

[20050824|7|006327|000000|216.230.93.198]

Bro OMG...I have 2003 that went from 19 to 12 and ran 12-15 consistenlty for no reason. I did the same as you and they are unable to find anything wrong. I was told to wait until it looses an injector or throws codes. I read another post on different forum for this exact thing. THey have a problem i think but don't have an answer. These trucks dont just drop that fast for no reason. If you hear or find out what it is please let me know i will do the same. I went from 600+ miles a tank to 400-450 at best. My truck has a whole whopping 27k on it.

Tim

[duraace9sp]

LOL----GM at its best----now the motor had gotten much "louder" all noise---and the dealer (parkway gmc) says i have a chevy and they will no longer take any chevy's unless its a road emergency---and if i want it looked at i should find a chevy dealer!!!!
I see all the wonderful GM stories are still being validated!!!

[More Power]

duraace,

Here's what I would do.....

I'd clean the MAF sensor using an oil-free automotive spray solvent.

I'd carefully go over the engine, looking for any sort of problem, i.e. kinked fuel lines, loose electrical connectors, damaged wiring, loose hose clamps on the air inlet system from the airbox, loose clamps on the intercooler plumbing, etc, etc.

If no solution, I'd buy a Predator, and look at all the various engine sensors, i.e. fuel-rail pressure , injector balance and fuel rates, and all other engine sensors that could contribute to a running problem. One of the other threads here lists what you can read with the Predator - tons and tons of stuff.

Take notes of what you find, then post some of the data here in this thread.

I'd also check to make sure there isn't a dragging brake(s), the trans is shifting correctly, the 4WD system is disengaging, and the balance of the powertrain is not contributing in some way to a fuel economy/power problem.

The following image is an example Tech II Scan Tool snapshot of a 2001 LB7 Duramax at idle. This image came from Martin Smith, who is an ASE certified GM diesel tech from BC Canada.

http://www.thedieselpage.com/images/Msmith1.jpg

MP

[Tough Guy]

I recently spoke with a young man who had an '03 Dmax that suffered from similar symptoms, low fuel mileage and noise. The diesel mechanic he spoke with looked at the fuel system and found a leak on the suction side. They replaced the leaking fitting and problem solved.

Cheers

The "Boy" TG ;)

[dcalex]

Man....other than the practical suggestions above, I would be on a letter writting campaign that wouldn't end until they come begging you to let them fix your truck. Thats outrageous, and just doesn't have to be tolerated. First thing; they have egg all over their faces with the power steering pump having "disappeared"...this whole thing smacks of fraud from one end to the other. I might not win, but they sure as h*ll would know they'd been in a fight.

[duraace9sp]

well----i do like and will follow up on all the above----as for the fuel leak---i did have one in the first motor in 2001---and the dealer (parkway) stated they couldnt run a leak/fuel pressure test with the post oem secondary fuel filter installed----so i took the truck back and removed the filter assembly--and actually talked to the mechanic who said he absolutely checked for leaks and fount none....accuracy????
if all was well i would have no doubt???

...what i do know is power and mileage loss were immediate-----and the huge increase in noise followed shortly thereafter......
no i am on hold.....

[madmatt]

have your dealer check out preliminary information bulletin # PIP3125A, duramax low power or poor fuel economy. it was released Nov. 15 2004, just came up on it Friday.

[madmatt]

you'd be surprised @ the number of techs who do not read or refer to bulletins. i scan through them daily.

[duraace9sp]

hi again---madmatt----what does the bulletin say????

...thanks!

[Nix]

Where do you find technical service bulletins? I am quite certain that my local dealership is being shady about the technical bulletins.
I had the fuel pressure regulator replaced at around 60K on an '01 D/A. Before that on an extended road trip with the cruise set at 55-60 I saw as high as 25 mpg. Since I had the regulator replaced, I get about 20 on the highway, 16.5-17 in town. The truck has not idled properly since the fp regulator replacement. They tried to tell me that it was not covered under the 100K engine warranty, but that they would cover it since they initally told me that it was a warrantable item. Nothing like having the service manager insult me by telling me that the fp reg in a high-pressure common rail system is as prone to failure as the fp reg in a cavalier :mad: ! Should I insist on my less than forthcoming local dealership checking the injectors? I installed a K&N cold air kit and Amsoil lubricants aroud 25,000 miles. The truck has 96K miles currently. Any symptoms to look for with injector failure besides ses light, smoking, severe power loss, etc? Thanks to all for the great forum.

[madmatt]

it's too much to type really but somewhere on this site is a link to a site w/ TSBs and such. This preliminary information bulletin # PIP3125A basically just gives some operating specs to watch and says to get a snapshot of the affected engine and compare to a known good engine while operating @ the same conditions. as for the warr. issue, yes the FPR is a cover item under the 5yr/100k factory warr and is ALSO covered under the federal emissons warrenty which is I belive is 8yr/80K w/ no deduct. so in your case it should have been covered under warr @ no charge.

[madmatt]

also NIX there is a bulletin on your FPR failure that states that after removal of the exsisting FPR it should be inspected for contamination and if contamination is found the entire pump should be replaced along w/ the fuel filter. the fuel filter in this case would be @ your expense. Why did you have your FPR replaced in the first place. your curent milage sounds about normal honestly and would probably have a hard time convincing any shop to investigate 20mpg.

[Nix]

madmatt, I had a surge at idle, intermittent at first, and then consistently lurching at idle. My mpg dropped to 15-16 regardless of city or highway. First they told me that they could not find the problem, them they told me they re-flashed the computer and it was fine. I drove it away, turned around went back to the shop. That's when they said it was the fpr. No mention of having to check the inj pump, just some bs about the fpr not being covered by the 100K warr., but since they told me that it was that they would fix it free of charge :rolleyes: . My mileage is now 19-20 highway (even with going up one size in tires), but the idle has been somewhat rough(compared to when I bought it)and once in a while I hear a slight clack that is reminiscent of Power Stroke :eek: :eek: :eek: :eek: , albeit intermittent. Since then, they tell me that there are no service bulletins for my vehicle, and deny the GM injector warranty extension :mad: !! I'd be up poo creek if not for sites like this one :D :D . Thanks everyone! Should I insist on having them inspect the injectors?

[Nix]

madmatt, do you think the bad FPR could have boogered up any of the injectors? Just wondering....I usually stick to the old adage "if it ain't broke,...but in light of the FPR and idle/intermittent clack symptoms, should I insist on injector inspection/test? If they deny me, who do I write to to complain? Thanks again.