Engine Over boost Condition

[navybanker]

Pulling trailer over 4,000 ft mountains in Oregon and CEL stating engine overboost on turbo. Portland dealer said common problem for Duramax pulling heavy trailer in mountains. I was not really pushing it going over mountains. Portland dealer checked turbo by driving it 50 miles without camper while checking. Said turbo but since tested okay on trial run would not replace. They could not duplicate pulling trailer in mountains. Then later in trip a local dealer in small town (ranching area) said not to exceed 2500 RPM going up mountains. We just "talked" to second dealer since late in the day. CEL cleared after third restart. Second dealer also said to add Cetane to diesel fuel. Both dealers said common problem with Duramax engine. How do you get GM to fix this problem?

[The Bone]

Hook up the trailer and take them for a ride in the hills. Its the only way to show the tech what the problem is. I wouldnt let a tech drive my truck pulling my trailer but he may want to data log the drive.

[RKassl]

We have towed in many mountains with our Dmax pulling the Montana never saw this condition before. Are you saying that it set an engine code or did it display the message on the dash?

[mlh]

Is over boost a problem? Is it going to hurt anything? If it's going to hurt something it's a problem if not forget it. They have got to have boost to make power. My truck will a lot of times go to over 40 pounds of boost. My truck is a Ford. Know yours is a Chevy but if it's not hurting anything I would drive it.
Lynwood

[bigskyjimmy]

It has happened to me a many times when I had my 2003 LB7 Duramax with a PPE boost controller AND my Banks tuner on tow mode,No big deal I would just pull over when I got the chance and cleared the code with my tuner,No harm done but when I got my 2007 I did not put the Boost controller on and I still use the Banks tuner on tow mode and have not got that CEL yet but then again I have not climbed any HUGE Passes yet with it,Are you the original owner of the truck? and do you know if it has a aftermarket boost controller on it?? and do you have a tuner on it?,when I get a chance I am going to install my ATS Boost Fooler and that will stop the CEL's

[richfaa]

We have gauges on our Ford. We watch boost and Exhaust gas temps(EGT) closely when going up steep grades. As you pull a grade the Boost,. EGT and RPMs will increase if you try to maintain speed. We are more concerned with turbo temps than speed up a hill.
We also keep a eye on Tranny temps .We drive by the gauges and may top a step grade at 45/50MPH. We are told the the tips of turbo blades are white hot at 1300 degrees .Our gauges will alarm at 1200 degrees and we will back off to keep below 1200 degrees. Heat kills turbos. We never use cruse control on grades as that will try to maintain speed and drive boost, EGT an RPMs to dangerous levels.

I do not see how you can keep below 2500RPMs on a steep grade.

[mlh]

I agree with Rich keep the temps in check. What we don't know is was over boost 1% over or was it 50 or 100%. The Fords will develop about 38 pounds stock. Mine will go up to about 45 pounds and I have heard of them going well over 50 pounds with no ill effects.
Lynwood

[leemedic]

I had a similar issue. It was stuck Stator Vanes in the Turbo in my Ford PU

[bigskyjimmy]

He does not own a Ford guys a Dmax does not boost 35-50lbs stock Again it is No big deal for a Duramax to trip the Overboost CEL over about 25lbs of boost it has happened to a lot of us that have tuners etc.. install a gauge a safe boost for a LBZ Duramax like mine is 26-34 lbs anything over that the EGT's skyrocket,I myself do not like going over 30 lbs on my LBZ and I think it is the same for a LML Duramax like yours,if you are boosting over the low 30's on a stock Dmax something is not right

[richfaa]

I did not know there was that much difference between a Dmax and a Ford. I learned something new. MLH was referring to Ford boost with a tuner. Mine is stock and I have seen 38 on a hard steep pull. With a boost of 50 I would not want to see what the EGT's were. He did not say if he was using cruse control.That would have a effect on boost.
I like to be kind to my turbo's as they are very expensive to replace.

[bigskyjimmy]

Your right Rich he did not say if he was using cruise and that would effect boost and I'm with ya I am careful not to get tuner happy I would not want to replace a Turbo that would break the Bank for sure

quote:Originally posted by richfaa

I did not know there was that much difference between a Dmax and a Ford. I learned something new. MLH was referring to Ford boost with a tuner. Mine is stock and I have seen 38 on a hard steep pull. With a boost of 50 I would not want to see what the EGT's were. He did not say if he was using cruse control.That would have a effect on boost.
I like to be kind to my turbo's as they are very expensive to replace.

[mlh]

I would see 1100 degrees or lower and boost of under 40 pounds coming up Fancy Gap at 70 MPH. Don't forget my camper is 9200 pounds and your Montana I think is 12000 pounds but I have 373 gears you have 410s. No I would not be using CC. By the time I get to Fancy Gap I'm almost home and you have hundreds of miles to go. What do you see on Fancy Gap?
Lynwood

[mhs4771]

My 2011 Duramax has never thrown such a code and last summer on our Alaska and Western Parks trips we went well over 9000 Feet pulling a little over 17K, but then again we're bone stock.

[drknapp]

Ours threw the code once a year or so ago. Since then I ease up a bit going over the hills and haven't had any problem with it since.

[Phil P]

Hi

Over boost will damage the engine if it is for a long period of time.

The engines that I have operated and maintained that had a max boost and time limit for that max boost were commonly limited to 5 minutes in the high or over boost mode.

These were both diesel and gas engines ranging in HP from 315 to 2,000. The procedure was commonly referred to as the max power rating with a limit of 5 minutes.

We traveled the Rocky Mountains in the summer of 2010 and only experienced one CEL and the dealer in Spokane Washington said it was a variable guide vane position error With my experience with variable guide vanes I would call this an over boost.

Phil P

[navybanker]

I don't use CC going up hills. The codes reported by Portland dealer were P2599, P0234 and P0672. They replaced glow plug. That code had appeared in South Dakota on the way west. I thought that one was not an immediate problem but didn't realize other codes were happening later. The CEL was on for about two weeks. Also had message that DEF was poor quality and that was why stopped at Portland dealer. These same codes came back on traveling over Blue Mountains in eastern Oregon. Talked to dealer in Baker City, Oregon. Mechanic said turbo vanes were the likely problem. The first thing the mechanic in Baker City said when I said had engine overboost was are you pulling a trailer. Codes cleared after about third restart. Turbo vane position sensor was replaced last spring. Both dealers said the turbo is the problem but can not replace when checked out okay in the shop. I purchased the truck used and have put about 35,000 miles on it. It is stock as far as I know. We are now in Mountain Home, Idaho and no codes from Baker City,Oregon to here. We do plan on going I 70 to Denver later in trip?? Thanks,

[mlh]

I think the Chevy heads are more efficient than the Ford heads. The Chevy has aluminum heads that can be casted much smother than cast iron that were used on the 6.4 fords. Remember when people ported and polished heads to gain more power. I think the same thing is going on with these trucks. There is a lot of fraction in the cast iron heads that slows down air flow. You need more boost to overcome that friction and the Chevy heads are probably better designed.
Lynwood

[hunts800]

I a not a mechanic and most of these posts dealing with computer codes, turbo boost and vanes is beyond my are if expertise. I have, however, been towing with two Duramax's (2009 and 2015) all over the U.S. , Canada, (including Alaska) and have never had an issue. I do not use CC when towing, and frequently will put the transmission to manual mode in severe mountainous areas. I try to keep my RPMs between 2400-3000 when under heavy pull.

[TAKPAK]

With our 2015 Duramax, we've not had any codes show up, pulling any of the hills/mountains we've gone over. That said, I do not let the cruise take us either up or down the hills. Diesels are not meant to run "full throttle" like gas engines can do, the EGT's go way up. I keep the RPM's down. Usually it's pulling just fine at around 1600 RPM, which is the peak torque area. When it gets too slow, the Allison will downshift one gear and the RPM's will go to about 2100, which is approximate peak HP range, but then I start picking up speed and I back off on the throttle a bit. This is with a 14,000 pound fiver and an 8000 pound truck. I may be only going 45 when I reach the top, but at least I know I'm not frying the turbo or straining anything else.

BTW Navybanker, did you enjoy the Blue Mountains? I grew up driving truck over them for my grandpa and his feed store business in Prairie City.

[navybanker]

Takpak - We spent one night in Baker City and wished we had planned at least two. We toured the BLM Oregon Trail Interpretative Center and had a great steak at Haines Steakhouse in Haines (not far from Baker City). Beautiful area and we have enjoyed the info along I 84 on the Oregon Trail. A lot of the trail is "under" I 84!
Back to the turbo, the CEL didn't appear until we stopped at a rest area after crossing the mountains. I let the truck idle while at the rest break. Got back in and there was the CEL. The Chevy dealer in Baker City said to use Cetane each tank. No, he didn't sell it to me. He said GM charges a lot more than other places do for it. I am not sure what cetane does for the turbo. As I remember, the LLY I drove previously had an orange warning on the RPM gauge at I think 3,500 but this LML has "no" warning color on the gauge.