Would EGR issues cause trans slip?

dirtbike.mom69

New member
Jan 15, 2019
5
0
0
oregon
So not sure if it's okay to post on your thread for my question or if I need to start my own thread but I have a 2004.5 lly and I'm having issues I got 2 egr codes thrown and 1 incorrect 5th gear ratio code. I can get the numbers for ya but my question is could a bad blocked up egr be causing 5th gear to slip some how?
I know it's a silly question.
So I had a tuner on 3 since last summer when towing bikes to the coast and then left it on 3 because I loved the throttle response and the sound. Then last month when I was on my way to work I went to pass a truck at 75mph the truck just stalled out. I was able to slowly limp it to work and before i got off work i had my dad take it to his friends shop down the road to get me the codes. The first 2 codes thrown at me were insufficient egr flow and egr out of range or something to that. So I figured no big deal just gotta do the dreaded egr delete and efi live. Well a week later I figured hell I would take the tune on down to 1 and then drive her again. She had been doing fine then the same thing I went to get on her and limp mode again. (Sounds dirty) lol so I figured another egr code. Well this time it was incorrect 5th gear ratio.

So should I just have my dad fab me up a blocker plate and do a cheap hillbilly egr delete to see if I get another gear code before spending good money on wc fab delete and efi live. I just don't wanna fork out money if I need to rebuild. So could the culprit be my tuner and gunked up egr thats making her slip 5/4 gear?

Btw only 87,000 miles on her super low. When my toddler was little I used to drive around until he would fall asleep then just sit and idle when he would sleep so that I could get some shut eye. Super bad but I had no clue how bad it would be. I didn't realize sitting idling was a huge no no with that carbon building up.

Any input would be great but smart @ss comments need not reply. This is my first duramax and I'm a female so please don't talk to me like I'm stupid. I'm here for help not jacka$$ remarks.
Thanks in advanced.
 

SoCalMike

Member
Dec 12, 2010
758
16
18
SoCal
So not sure if it's okay to post on your thread for my question or if I need to start my own thread but I have a 2004.5 lly and I'm having issues I got 2 egr codes thrown and 1 incorrect 5th gear ratio code. I can get the numbers for ya but my question is could a bad blocked up egr be causing 5th gear to slip some how?

I know it's a silly question.

So I had a tuner on 3 since last summer when towing bikes to the coast and then left it on 3 because I loved the throttle response and the sound. Then last month when I was on my way to work I went to pass a truck at 75mph the truck just stalled out. I was able to slowly limp it to work and before i got off work i had my dad take it to his friends shop down the road to get me the codes. The first 2 codes thrown at me were insufficient egr flow and egr out of range or something to that. So I figured no big deal just gotta do the dreaded egr delete and efi live. Well a week later I figured hell I would take the tune on down to 1 and then drive her again. She had been doing fine then the same thing I went to get on her and limp mode again. (Sounds dirty) lol so I figured another egr code. Well this time it was incorrect 5th gear ratio.



So should I just have my dad fab me up a blocker plate and do a cheap hillbilly egr delete to see if I get another gear code before spending good money on wc fab delete and efi live. I just don't wanna fork out money if I need to rebuild. So could the culprit be my tuner and gunked up egr thats making her slip 5/4 gear?



Btw only 87,000 miles on her super low. When my toddler was little I used to drive around until he would fall asleep then just sit and idle when he would sleep so that I could get some shut eye. Super bad but I had no clue how bad it would be. I didn't realize sitting idling was a huge no no with that carbon building up.



Any input would be great but smart @ss comments need not reply. This is my first duramax and I'm a female so please don't talk to me like I'm stupid. I'm here for help not jacka$$ remarks.

Thanks in advanced.
Welcome to the site.

It would be best to start your own thread so you can get the help you need. I believe you have two different issues going in and in order to help you we need the codes the truck is throwing.
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
15,610
1,864
113
Mid Michigan
Moved your problem into it's own thread.



Rule #1 for asking for help -- include all pertenent info, especially any codes showing. Otherwise all anyone can do is guess, and that doesnt help solve the problem.
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,726
294
83
Boise, ID, USA
The EGR codes won't cause the transmission to slip. It sounds like you have the classic slipping 5th gear. That is caused by more power than stock, and the Allison is designed to reduce clutch pressure when the torque converter locks, which makes 5th gear especially prone to slipping.

The solution is to have the transmission built. Better clutches are used, and among the various mods made to the valve body, the pressure knock-down is eliminated, which lets 5th gear hold much more power. But building a transmission is not cheap.

Back when I had a stock transmission, I was able to get a lot more life out of it once it started slipping by driving a certain way. Never just go full throttle in 5th, as the 5 --> 4 shift can immediately limp the transmission. And if you are wide open in 4th, let off before it shifts, as the 4 --> 5 shift will limp it too. If I needed to pass someone, I would manually put it in 4th (hold the Tow/Haul button for a second) before starting the pass, so it couldn't use 5th and limp. Got some 50,000 miles out of the transmission after the first limp using this technique.

Once you save up and have it built, it will be a totally different truck. You can run a much bigger tune and it will handle it great. My brother and I run a tune I wrote that is 425 HP / 750 lb-ft at the wheels on the stock motors with built transmissions, and it is a riot. Makes them run slightly better than the brand new trucks, but without spending $80,000.

If you do block the EGR system, you will need to either add a fooler ("Finger Stick") or a EFILive tune to prevent it from immediately setting the check engine light. I would see if the codes come back, and leave it alone until then. But probably best to start saving for an EFILive tune in the future too.
 

frankenstien

Member
May 25, 2015
587
2
18
Fairbanks,Alaska
Fill out your signature with your truck info, modifications etc. That will help us help you.

As for the slipping in 5th, in my case I was able to turn my tuning down and change my driving habits, did OK for about a year until I had the trans built.

If/when you have your trans built, have it done by a reputable shop that is good with the Allison or get a good kit if you are planning on doing it yourself.

It will save you a lot of headache and money in the long run, looks like you're in Oregon, maybe time for atrip down to Inglewood transmission in california