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02 2500HD not shifting 4-5 under heavy load

961 views 6 replies 5 participants last post by  faSST94Impala 
#1 · (Edited)
I've been reading posts all morning and still could use some advise/opinions as I am still not certain what is going on.

Background: 02 Duramax crew, 140,000K and I have been running a Hypertech Stage 3 since this summer. I have been changing spin off every 12.5K along with fuel filter and change ATF at 25K intervals. It's my daily driver and I drive very conservatively in primarily city traffic and occasionally haul a 6-7Klbs car trailer.

Last change the ATF was dark red but no burnt smell. Used Valvoline Maxlife Dex/Merc. I hauled a 6K load over the North GA mountains (joke for you guys out west) last week with no problem and I was passing people going up the mountain. Fast forward a week.

On way to work yesterday I got into the trottle to pass some a$$hole in a toyota (common in Atlanta traffic ;) who was driving eratically. Rolling at 10mph, I floored it and it shifted at about 3K through the gears but then got hung up at 50mph between 4-5? or 3-4? I backed off and it shifted.

Not sure how long the condition has existed because of High Diesel fuel costs, I haven't pounced on it like that for months. I tried to recreate the problem last night and it's not consistant. It got it to hang up again but after I put it in the haul/Tow mode it shifted fairly smoothly under WOT. I then turned off haul/tow and it shifted ok. The ATF is bright red, no burnt smell. I checked with the programmer and NO CODEs were thrown.

I will change the fuel filter and go to Stage II on the HyperTech. Hopefully it will buy me some time. From other posts, it sounds like I need to start saving for a rebuild. Any good Shops in Atlanta Area?

Thanks for your thoughts in advance,

Mark
 
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#2 ·
Sounds like fuel filter problem. IMO 25K on a fuel filter is way to long- The CP3 may pull dirt through a dirty filter and damage your fuel system.:)
 
#3 ·
JC, I change fuel filter at same time I do the Spin-Off at about 12.5K. I change ATF every 25K. Regardless I hope that is what it is.
 
#6 ·
IM in the same boat mark is.. so any suggestions would be great. i also still have the origional injectors too. 242,000km on them
 
#7 ·
Issue Resolved

Thanks yet once again to Diesel Place!!! I personally replaced the fuel filter less than 10,000 miles ago and would have never guessed that it was effecting the transmission.

So I replaced the fuel filter today and truck now shifts perfectly under WOT. I cut open the old filter and was shocked what I found. It was full of "dirt" and black crap. I guess I got a bad batch of fuel somewhere.

I love this forum, a stealership would have made a great deal on a ally rebuild I'm sure.

Thanks everyone.

Mark
 
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