Chevy and GMC Duramax Diesel Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
915 Posts
Discussion Starter #1
Last weekend was my first pull and i took 3rd outta 10 trucks with a 280' 10" but im pretty sure my truck hit 4th in 4lo even though i had the shifter locked into 3rd now mind you i was more than likely hitting the limiter so im thinking the alli shifted to 4th to protect the engine?. So last night i tried feathering it down the truck which helped keeping it in 3 but i lost a ton of momentum near the end and winded up with like a 270' pull. What should i do?
 

·
NewEST Spinny Thinggg
Joined
·
4,291 Posts
Get a tcm tune to lock it in 3rd
 

·
Registered
Joined
·
915 Posts
Discussion Starter #4
10-4 where can I get that done? Can efi do that or do I need someone with allison software?
 

·
Registered
Joined
·
915 Posts
Discussion Starter #5
night bump for myself :)
 

·
Registered
Joined
·
128 Posts
More than likely you were feeling the converter lock up. It can feel like another shift and it will bring ur rpms down like a shift as well at first. But, if you want a good tcm tune, give Mark Broviak a call at Danville, he wrote my tcm tune and it has ran flawless! Good luck!
 

·
Registered
Joined
·
156 Posts
i find it hard to believe it would have shifted into 4th on its own.
If you have it in 3rd it should never shift up
Especially only goin 280ft I've seen logs of my pulls with 3700-3800 rpms and it doesnt shift out of 3rd. In hindsight at some pulls, i thought i should of shifted it up but a stock turbo/fuel truck doesnt have enuf to pull in 4th gear unless its a long pull or a light sled.
Converter lockup would occur in second gear and would be hard to notice at full throttle in a sled pull.
 

·
Registered
Joined
·
13 Posts
Agree, if it was in Manual 3 mode it would not shift up to 4th. Just let it hit the limiter and keep it to the floor, will be the best bet for getting down the track. A little larger tire or some chassis work will help to keep the rpm in check also!! Good luck next time out.
 
1 - 8 of 8 Posts
Top