Help guys, I'm broke down in Front Royal Virginia , 12 hrs from home, (Ontario)... Truck ran great until today, coming home from Florida, starting to buck real badly, missing real bad, finally threw CEL and slowed ( limped) pulled over drained fuel filter water drain, no better, changed fule filter , no better, made it to a stealership and it closed, found mechanic with scanner, NO CODES, WTF ?? Did the #2, #7 fix in park lot...no better...runs great but bucks wildly under load please help gotta be to work Monday morn..............currently stuck at closed GM dealer, in Fifth wheel. Thanks

I wonder if you have bad fuel. I say get over to autoparts store and have them scan it and see if they see anything. Pick up fuel filter and change it. Take a look at the fuel and see if it looks different or smells different. Depends on the EFILive tuning and if some of the DTCs have been set to no mil and then you may not know if they are being thrown.

If the CEL went off I would think there be something.

Brian

I wonder if you have bad fuel. I say get over to autoparts store and have them scan it and see if they see anything. Pick up fuel filter and change it. Take a look at the fuel and see if it looks different or smells different. Depends on the EFILive tuning and if some of the DTCs have been set to no mil and then you may not know if they are being thrown.

If the CEL went off I would think there be something.

Brian

CEL was on , I recycled key several times and light went out, can't get it to come back on for scanner, going to Auto zone right now for fuel scan

Thanks !!!!

Try grabbing some Power Service 911 and throw that in your tank. If you did pick up some bogus fuel, then that should help...

Is it snowing over there? Any chance your air filter is covered in snow?

Check for harness rub thru at alt bracket.

Yeah that would be the other injector harness related issue on the LLY.

Brian

Check your oil to see if by chance there is fuel in it (dropped injector) Check fuel rail pressure if possible. See if fuel is leaking. My truck showd the same symptoms with a weak Cp3 that went south. Hope this helps

Check your oil to see if by chance there is fuel in it (dropped injector) Check fuel rail pressure if possible. See if fuel is leaking. My truck showd the same symptoms with a weak Cp3 that went south. Hope this helps

Back at internet bar, nobody in town could check fuel, I alweays use a little Powerservice, just dumped a load into her, no snow, roads are clear, .....no issue at alternator rub spot, previously fixed....truck is running great solo ....towed trailer again briefly after spending an hour under the hood checking wires etc (I'm no mechanic ) but saw nothing...no fuel leak but can't check pressure now , beauty town but I need to get out !!!
Truck is idling outside to hopefully clean a dirty injector...I gotta eat or I'm gonna pass out

Thanks guys ......anything else I can check ?????

Oh yeah, checked oil, seems fine, no smell anyways

Still no codes? I am just at a lose without scanning the PIDs for seeing what is going on. You have a K&N filter and I assume one of those oiled types. I wonder if MAF sensor is dirty and or oily. You can remove and try some MAF cleaner on it. If you have had this filter a long time then it be time to replace. Even though you can recharge them they can thin out or feather the material inside since the Duramax pulls so much air in.

If I think of anything will post back. Hope you get it figured out.

Brian

Dude that had scanner said that there was a transmission code thrown, It did limp but I think it was because the engine was running sooooo bad that the tranny wanted to downshift but there was no power there to help it do so. Its not a tranny issue, engine was dying when it limped, I think I reset the computer before he scanned it for codes (dumbass) , anyways, he did watch the injectors and said they looked great, all the same, no issues, I think the only thing blocked by EFI on mine is the EGR and the usual speed limiter

Rob

If it was "bucking" wildly, did you have something in the tank that got sucked up into the lines? You've done everything else, pick up an extra filter or change it if you keep a spare one in the back. If it was a piece of gunk hopefully it didn't go past the filter.

Only bucking i ever had was Allison related but of course that was getting on it. Pretty sure it was the torque converter more than anything. So here is my thinking.

You drive in tow/haul mode? If so when it goes into second and up is when it starts bucking?
If you pull trailer in normal mode does it not do this till you get up towards 5th gear?

Check transmission fluid to be full and not burnt?

Brian

Thanks so much for the replies !!!

I changed filter prematurely before leaving for Florida, and changed it on the side of the interstate 66 when this happened ( scary), I really hope you might be right that something got by the filter, and I might clear it up by running it as I type

I looked at the MAF with the mechanic and we agreed it was clean, I do use the K&N simply because I recently had a paper filter sucked partially up my intake tube, now I very lightly oil my filter and I like it for the rigid screen.

again thanks Guys

hogpenpuller I live here in front royal I just moved here recently so I dont know any mechanics but if I can be of any help let me know I can pm you my # , but most of the guys on here know more about these trucks than I do :( but if I can help I will try :)

Only bucking i ever had was Allison related but of course that was getting on it. Pretty sure it was the torque converter more than anything. So here is my thinking.

You drive in tow/haul mode? If so when it goes into second and up is when it starts bucking?
If you pull trailer in normal mode does it not do this till you get up towards 5th gear?

Check transmission fluid to be full and not burnt?

Brian

Great questions....trailer is around 14k lbs so I always use tow/haul, starts to buck in 4th continues into 5th.
I have NOT tried trailer towing without tow/haul ON. Is this possible ?
Tranny fluid is new as well and is clean as new. Replaced with eng oil before trip.

Again , I'm no mechanic , but I'd be shocked to find out this is tranny related, seems to be engine to me but I'll try anything !!!!

If bucking in 4th and 5th I suspect some Allison Clutch pack and or torque converter damage. Usually in normal mode the torque converter will not lock till 4th or 5th gear. In tow haul it will start locking in the gears 2nd on up. If in 4th that is C1 and C2 clutch pack and C2 is the weakest. For 5th it is C2 and C3 clutch pack for that gear. If you lock it to 3rd gear and it does not do it then I would start to lean towards the Allison being the issue. Might set it to 3rd gear max gear and take it for a drive. Then pop it to 4th and see what happens and then back to 3rd. Lets hope not the issue.

Brian

hogpenpuller I live here in front royal I just moved here recently so I dont know any mechanics but if I can be of any help let me know I can pm you my # , but most of the guys on here know more about these trucks than I do :( but if I can help I will try :)

I'm the guy in the corner crying at Houlihans Bar/Grill, there's only me and two ther guys here doing that so yell Diesel when you come in and I'll buy you a beer if can make it here, I'll be here for awhile :beerchug:

If bucking in 4th and 5th I suspect some Allison Clutch pack and or torque converter damage. Usually in normal mode the torque converter will not lock till 4th or 5th gear. In tow haul it will start locking in the gears 2nd on up. If in 4th that is C1 and C2 clutch pack and C2 is the weakest. For 5th it is C2 and C3 clutch pack for that gear. If you lock it to 3rd gear and it does not do it then I would start to lean towards the Allison being the issue. Might set it to 3rd gear max gear and take it for a drive. Then pop it to 4th and see what happens and then back to 3rd. Lets hope not the issue.

Brian

Ok, just went out and did two hard launches on 522 in tow/haul and in normal, ....both felt great, first to fifth, lugged it in normal in 5th and layed into it hard (without downshift though) and it pulled real hard..no limpy..

You have no idea how much I appreciate your help !!!, so please continue..but I still think it is motor ...fuel ?? motor was bucking (I think) felt like cylinder going down

Is there such a thing as a plugged injector ?? What can I do if it is . Can I remove injectors and purge them ??

No abnormal smoke, coolant is right on the line....???

May be bad fuel but have no way to tell, need to look at everything I can !

Well maybe I will think of something in my sleep. Only thing is scan and monitor the different PIDs as you drive with GM Tech II or EFILive. You have EFILive tune but do you have the hardware?

Brian

Well maybe I will think of something in my sleep. Only thing is scan and monitor the different PIDs as you drive with GM Tech II or EFILive. You have EFILive tune but do you have the hardware?

Brian

Thanks Brian,

No I don't have the hardware , tune installed by a shop in Ontario, guess I''l have to wait for the tech II. Is this going to be an issue with my EFI tune installed ?? I do not care about warrranty as it is useless anyways, but will Tech II be able to see what it needs to with my EFI tune installed ???

The Power Service 911 is for situations where you wind up with bad fuel, gelled fuel, or both. It's highly concentrated and has been known to work miracles. I would not disregard or gloss over this one. If you have anything that got past the filter, this stuff ought to help dissolve it and restore things.

The Power Service 911 is for situations where you wind up with bad fuel, gelled fuel, or both. It's highly concentrated and has been known to work miracles. I would not disregard or gloss over this one. If you have anything that got past the filter, this stuff ought to help dissolve it and restore things.

Randy,

I use the grey jug in the winter and the white one in the summer, I thought you were joking with the "911" so thanks for reposting. Should I get some and dump it in too ?? There's now quite a bit of the "grey" stuff in there already. If I don't find "911" is there an alternative ? You are not wasting your time...I will do anything (almost ) you say right now !!! THANKS

Power Service 911 is in a bright red bottle. Don't personally know of any alternatives... though there might well be.

Maybe check the large electrical connection on top of the drivers side valve cover. Mine was just barely loose and caused my truck to buck and go into limp mode. Took over a month to finally find it, but it fixed it. Good luck.

GM Tech II will be reading fine. May read things out of specs depending on the changes to a tune though. But will work.

Brian

Maybe check the large electrical connection on top of the drivers side valve cover. Mine was just barely loose and caused my truck to buck and go into limp mode. Took over a month to finally find it, but it fixed it. Good luck.

Gone out to check, .....Thanks

GM Tech II will be reading fine. May read things out of specs depending on the changes to a tune though. But will work.

Brian

I thought it would but wasn't 100 % sure, .....so, no need to put back to stock settings then, considering it has run great up until now ??? It should read as if it was a stock tune , right ?? If so, I wonder why it didn't throw an engine code...(again, I'm no mechanic I just feel it is engine, I been wrong before) . but trans seems to be fine under hard throttle without trailer...

Well not pulling 14,000lbs extra weight. Can depend on the damage to the Allison if there is any. No idea as to why no codes. What is 552 by the way?

Brian

Well not pulling 14,000lbs extra weight. Can depend on the damage to the Allison if there is any. No idea as to why no codes. What is 552 by the way?

Brian


I totally agree with you, my attempt was to get another code under hard accelleration...probably meaningless though, that is alot of weight, I do baby it when I can, n o hard throttle with trailer... 522 is local SR, (state road) I assume, goes right thru Front Royal here.

Still jerky under load without trailer, no CEL, lots of run time with "grey" Power Service....no concentrated stuff yet...unless Tequila counts, realise I'm here for at least the night so "F" it !

As long as your drinking the good stuff sounds like its all you can do. Hopefully someone in the area catches this and can help.

Brian

As long as your drinking the good stuff sounds like its all you can do. Hopefully someone in the area catches this and can help.

Brian

Thank you everyone for your ehlp, lehp.........help..yup thats the one, I'm here so make the best of it right...Teq. Budweiser is the rest of this day !!

Hey bud, few questions. Does the miss seem as if the sequence was timed? as in, does it feel like the same injector misfiring? Or, does it happen spontaneously as you load it down more and more? I have done great testing with my LLY and CP3; faults, rail pressure issues, bio fuel, etc. Let me know as much as you can remember.

have you done the shime kit on your fuel rail pop off valve.... sounds like a candidate...

Hey bud, few questions. Does the miss seem as if the sequence was timed? as in, does it feel like the same injector misfiring? Or, does it happen spontaneously as you load it down more and more? I have done great testing with my LLY and CP3; faults, rail pressure issues, bio fuel, etc. Let me know as much as you can remember.

Great...now my head hurts too !! Got a great sleep though.

I can't say if it was sequential or a single injector, just began to shudder slightly off and on and as I increased throttle to make up for the power loss it began to buck so I let off for a bit, came back into throttle and it bucked and kicked and then threw a CEL and to the shoulder we went. With trailer unhooked it feels off and on like its low on power and motor seems noisier (clattery) than usual.
I can't this morning get it to act up but I afraid to get back on interstate because I have trailer with my Harleys in it and I'm in a pretty good position right now, sleeping at GM dealer til they open tomorrow.

Do I risk trying it again or stay put ???????

have you done the shime kit on your fuel rail pop off valve.... sounds like a candidate...

Thanks, I don't know anything about that one, I'll throw that one at the GM tech tomorrow. Without me searching on here , Is this something I can do on my own ??

its not a simple project and the gm tech isnt going kw more than likely,but what it does is if the fuel rail pressure get to high its suppose to bypass back to the return line back to the tank...this value will get weak and then under a load are hard accelration the value opens prematurely starving the engine for fuel....it does different thing sometimes it will throw a light...low rail pressure...sometimes nothing, but it will act like a fuel filter clooged to a bad injectors...

I would drive the truck till it is up to operating temperature and then you can try pulling the trailer again but if starts up then no. If you tried while still cold that may not cause it to act up till certain other things are ready as temperature nears operating temp.

Brian

holy shit hogpen i hope u get things figuired out man!! good luck!!

Great...now my head hurts too !! Got a great sleep though.

I can't say if it was sequential or a single injector, just began to shudder slightly off and on and as I increased throttle to make up for the power loss it began to buck so I let off for a bit, came back into throttle and it bucked and kicked and then threw a CEL and to the shoulder we went. With trailer unhooked it feels off and on like its low on power and motor seems noisier (clattery) than usual.
I can't this morning get it to act up but I afraid to get back on interstate because I have trailer with my Harleys in it and I'm in a pretty good position right now, sleeping at GM dealer til they open tomorrow.

Do I risk trying it again or stay put ???????
I see you have efi live, so are you able to return it back to stock right now or not? It appears your fuel demand is not able to be met by the injection pump or another component of the CR system. I saw a post about the rail pressure relief valve being shimmed. I think you would have crossed this issue before if that was the case. What can happen though, if its been opening on a regular occassion,(due to high rail pressure) the pintle in the valve can fracture. I know this b/c mine did while I was in Alabama a few years ago and I had similar issues pulling 12000lb trailer. This will cause the rail pressure to bleed off constantly resulting in a dramatic loss in power. The confusing part is, the injectors usually become less noisy when there is less pressure. I have to go on a road call in NY now, I will check back in a few hours

Hogpenpuller - I'm assuming the dealership you're speaking of is Jack Evans Chevrolet? If they can't help, I know someone who probably can. Dave Sackett has a shop between Jack Evans and Auto Zone, right on Royal Ave. He got my 6.5 running again,(it's at my parent's horse farm) and he's a very generous/smart/obliging kind of guy. Let me know if I can be of further assistance. BTW, you could leave the LLY, and bring the 6.5 back to Canada if you like....;)

If you can get back on the Interstate and just take your time you can go west on I66 to I81 North go to the Virgina exit 323 which should be at the WV/ VA line and there'a a Pilot Truck Stop they will have a diesel mechanic on duty, hope that helps a little,
Randy Briggs

First of all, I want to thank all you guys for your time and help, means alot when you are stranded alone, a long way from home !!!!

Sooooo, I loaded the almost full tank of fuel full of all the conditioner and injector cleaner I could buy in Virginia and then drove truck real hard and fast to get rid of some fuel and hopefully clean out a dirty injector or clog or whatever. Once at half full, I filled it up again , hooked up trailer and went backwards (East) to make sure I could at least get back to where I was. Truck ran so I chanced heading up to I81. Truck ran well so I ran hard to get rid of that fuel . Filled up at Flying J and she's back to 100%.

I am certain now that this strictly fuel related and this is my last purchase at a small "discount " fuel retailer.

Again, thank you for all your advice, and believe me I checked everything that you guys told me to.

sweet glad to here it,I swung by the dealer you were at earlier but you had already left,was just going to see if ya needed anything:)

you might wanna shim that value before you do get in a bind with it

First of all, I want to thank all you guys for your time and help, means alot when you are stranded alone, a long way from home !!!!

Sooooo, I loaded the almost full tank of fuel full of all the conditioner and injector cleaner I could buy in Virginia and then drove truck real hard and fast to get rid of some fuel and hopefully clean out a dirty injector or clog or whatever. Once at half full, I filled it up again , hooked up trailer and went backwards (East) to make sure I could at least get back to where I was. Truck ran so I chanced heading up to I81. Truck ran well so I ran hard to get rid of that fuel . Filled up at Flying J and she's back to 100%.

I am certain now that this strictly fuel related and this is my last purchase at a small "discount " fuel retailer.

Again, thank you for all your advice, and believe me I checked everything that you guys told me to.
Great news bro! By any chance, did you remember where the place was you fueled up with the poor fuel? I want to make sure I or any of us for that matter, dont get fuel there! Im headin down to Daytona on Wed for Bike Week. I def want to make sure I miss that stop! Thanks and good luck.

That's great news man... oh the horrors I've heard about low volume diesel stations and all the problems lousy fuel cause people. That's why I do my best out of town to only buy fuel from truck stops... where plenty of professional truckers are also spending their money.

Great news bro! By any chance, did you remember where the place was you fueled up with the poor fuel? I want to make sure I or any of us for that matter, dont get fuel there! Im headin down to Daytona on Wed for Bike Week. I def want to make sure I miss that stop! Thanks and good luck.

Bealeton Liberty
11069 Marsh RD
Bealeton , VA
22712

Pump #2 33.795g $2.959/gal $100.00 total

Yeah I keep my receipts, lol

Have fun at Bike Week, we spent some time in Daytona previous week, place was beginning to set up , it was awesome to see, wish I could have stayed.

That's great news man... oh the horrors I've heard about low volume diesel stations and all the problems lousy fuel cause people. That's why I do my best out of town to only buy fuel from truck stops... where plenty of professional truckers are also spending their money.

I had just woke up and began to drive from Roanoke Rapids, got quite a ways without a coffee, saw this empty station (wonder why?) with large lot with store for coffee, in I went.
Learning here is easier isn't likely better for you, or something like that.

Glad you got going again.

Brian