Duramax Sledhauler Diesel ECM Fix

[Rockmeister]

I know this isn't exactly sled related, however I and a few others have run into this with our sled haulers, thought I would pass on the info!

I have a 2001 Duramax that would go into "limp home" mode and not allow more than 65 MPH or so on the highway.
Checked with many repair shops and they all wanted a minimum of $3000 to replace parts under the manifold that MIGHT fix it.
NONE of them would guarantee it would fix it & many said they had no idea of it would fix it for sure.
So I put up with it for quite a while.

I was speaking with TDmax, one of our members here one day this summer about HIDs for his sleds, & turns out he reprograms ECMs for the Duramax.
The new ECM was $750 or so, still a bunch of money, & yet he said it would definitely fix my truck & I would like it!
Hmmmmm...

Ok, I thought about it for a while, finally I decided to take the leap of faith a few months ago & do it.
I VERY HAPPY I did!!
It was a relatively simply plug in, and made immediate improvements on my truck!

1) Added some serious horsepower, which I actually didn't care too much about, but my truck IS much more fun to drive now! lol
2) The best thing is, NO "Limp Home" mode"!
3) My mileage went UP 2 MPG!!!
Have gotten the best mileage I ever have with this truck, doing 80 down the interstate a few weeks ago.
4) The idle.
I didn't expect this either, however, my idle is super smooth now & starts easy as can be!
It was never smooth prior.

Am impressed.
If your Duramax has any of these issues can say this will fix it!
Can definitely recommend it!

Rock

 

[subaru2006]

Awesome. Another plus for this site and the vast knowledge of people. What was the deal with your truck besides what you already posted?

Subaru2006

 

[Rockmeister]

The Limp Home mode was the big issue to me. (Everything else was a GREAT BONUS!!)
Apparently the stock ECM is very picky about exactly what it wants to see & sets the limp home mode pretty easily.
(Even when it isn't warranted)
The fuel rail pressure was good, just not perfect like new. (The ECM didn't like the fuel pressure)
Have a ECM reader and can watch the fuel pressure in real time so I knew it was within acceptable range.

Not sure exactly what the new program does, but can say it does well & my truck runs the best it ever has.
(I bought my truck well used, so have no reference prior.)
Maybe TDmax can jump in and explain more.

He knows this stuff well.
Can say it was everything he said it would be.
I figured others could use this info.
It is a bunch of money we work really hard for & no-one ever wants to get "stuck" with something that doesn't do what is promised.
I took the leap & am REALLY happy!

Hope this helps!

Rock

 

[Agman 57]

Hey Rock that is good to hear. My Duramax has went into "limp Mode" twice over the years. Both for my fuel pressure being just a little low, and when I pulled a big hill, pulling a trailer it would go into this mode till I changed the fuel filter. Last year it did it to me when I was going home and was half way between Munising and the Bridge. I poked along for a little while at 25 MPH.
So after a few miles of this I called my dealer back home and ask if there was anything I could do. He said if it is not a major code or problem to disconnect both batteries completely, wait 1-2 minutes and see if it would reset?
I did that and it fixed it, back to 75 MPH again, just had to be careful not to push the pedal to hard and made I home fine. Changed my fuel filter and have been good ever since! Have learned my lesson, always start out the winter season with a fresh fuel filter.
Hope this helps if anyone gets suck along the road like I did.

 

[subaru2006]

You should be able to shut it down and restart it to come out of limp mode. If your rail pressure is "low". I would check/replace filters and see if that fixes it. Also check your cp3, look into aftermarket lift pump. Not sure on your years but I don't think duramax uses anything other than the cp3.

Subaru2006

 

[Rockmeister]

I also ran into the fuel filter issue.
Change it every year now, no matter what. lol

My rail pressure isn't actually "low" not by GM specs anyway.
It is lower than a brand new one.
That is to be expected due to wear.

The problem was, no one could say exactly why it was going into limp home mode & everyone wanted $3000+ to try different things.
That is some pretty expensive experimenting to find out that it may fix it, or may not.
Everyone was honest about it & told me they did not know why it was doing it & were not sure replacing the fuel pump buried under the intake manifold would fix it.
It was a definite maybe.

Yes, if you let it cool off and sit not running for a while, it would come out of limp home mode, but go right back to it pretty soon.

The limp home mode actually limits the RPMs to about 1900 RPMs.
So you are stuck at 25 MPH of so UNLESS you are very light on the throttle, accelerate lightly to 1900 RPM or so, then feather the throttle to let the transmission upshift.
Then you can accelerate more to the next gear etc.
All the while being careful not to make the transmission downshift. (Going downhill helps a bunch. lmao)
If you make the tranny downshift, you have to start all over again, from a very low speed, bad news on the highway.

So basically, my choices were:
1) Put up with it
2) Start throwing serious money at it until MAYBE it was fixed.
I wasn't happy with either of these choices.

TDmax gave me a 3rd choice that works very well.

Having run this for the last few months am very happy with it now.
Know it is a bunch better driving my truck!

 

[TD Max]

Thanks Rock!

The 2001 Dmax has some baggage when it comes to fuel pressure codes. The middle years did not have this issue as much, then it started to become an issue on 2006-2010's with moderately high miles.

Pull over key off reset often works, but having a handheld code reader is best. As said above fresh fuel filter before season PLUS always carry at least one spare plus the tools to change it on the road.

Every Dmax should have a lift pump added to help push the fuel up from the tank and avoid the black plastic Wix/Napa/Car Quest fuel filters as they are problematic and sub standard build in my opinion.

 

[FAMILYMAN]

I have had filters, cold weather and tranny load cause limp modes on all my duramax's. 05, 08 and 09. 05 had edge programmer. The 08 and 09 both have efi live, two different programmers. What I have found is warm up excessively and carry an extra filter. I have been unhooking batteries for years to reset.

Good info btw, those without efi live should experience the difference.

Btw, heavy hauler here.


2014 viper, mpi
2009 Phazer 144"

 

[Jim04RX1]

Food for thought. As a 20+ yr diesel mech. I vowed to never work on the Duramax, unforunatley I have had to break my promise to myself. After much studying and simular problems if limp mode occurs and there was a surge sometimes can result of a bad fuel pres regulaor. Normally I work on the bigger stuff. Hope helps out to everyone in the future.

 

[FAMILYMAN]

I like the idea of the lift pump. I bought an 85 dollar coder reader/clearer from Maco tools and cleared my codes. Have not been in limp mode since.


2014 viper, mpi
2009 Phazer 144"

 

[davessrx]

Rock I work at a GM dealer. Seeing it is an older d-max if it hasn't been done yet or recently I"m guessing you have injector issues. The stock programming on a Dmax left a lot on the table. The early Dmax's have tons of injector issues and it's huge money to replace them.....thousands. Some people use a diesel additive once a month, others use kerosene and at school a few months ago one of the teachers there swears by adding a quart of atf to the fuel once a month.....a lot of detergents in atf. Personally after having to work on them I will never own one. Just be happy you don't have a newer one with the DEF system. It's hard to beat a diesel for towing but man it sucks when they break.