6.7 cr bucking from 1000-1200 rpm

EverydayDiesel

EverydayDiesel

I drink diesel
Hello,

You guys are a lot smarter than I am so I need help tracking down a surging/bucking problem that I am having on this 2007 6.7 cr when the transmission(68rfe) locks up 5th (or 6th) gear from 1000-1200 rpm only.

Some background on this build
new QSB wide bowl pistons
new hamilton cam/pushrods/springs
new exceedy 350%
new firepunk compounds
new ats dual fuelers
new duramax top cp3 with new cummins fca
new fish tuning dual cp3 controller (i have a new ats controller also but search say they are problematic)
efi live tuning by les
new carillio rods
new 230 aeromotive lift pump
new fleece fuel bowl delete/dist block (new baldwin 15 micron w/f separtor and new cat 2 micron fuel filter)

Lift pump pressure holds steady at 9psi (mechanical) - i can turn this up or down
cummins cp3 (oem cummins fca) was working great before this build

on an early tune the truck would buck hard (harder then the brakes could hold) any time in drive or reverse but les has tuned that out. Now it only happens at low rpm (1k-1200) and gets progressively worse with more throttle. (a lot of black smoke when it bucks that comes out in pulses from the exhaust the same rhythm as the surging)

I am pretty good with a fluke volt meter. What would cause this bucking/surging at low rpm only? Any help is greatly appreciated!
 
The 68rfe is stock until i can finish saving for FP 47re
Trans was working fine before the build, I feel very strongly that this has something to do with the new parts on the truck, maybe fueling.

Guys on here are a lot smarter then me so I am hoping that they can tell me what to troubleshoot (with a volt meter maybe ?)
 
Any bucking or surging I’ve experienced in my own truck and a buddies ended up being either a limiter in one of the tune tables or a tune table itself either missing or not adjusted properly. Being it a 68rfe it could be something either with the trans tuning or efilive itself. Do you have a V2 or autocal you can datalog it acting up?
 
Ok I got a different file from my tuner and here is what happened. (I have a small log file of just the surging only. Send me your email and I will send it to you).

On this tune it surges at idle while in gear (R or D)
You can tell when I put it in to gear (reverse or drive) and you can immediately tell when I take it out of gear.
20180403 161339 - YouTube
20180403 161621 - YouTube

new excedy 350% wide spray angle injectors with wide bowl qsb pistons
new 230 aeromotive diesel lift pump
new baldwin f/w separator 15 micron
new cat 2 micron filter
new ats dual fuelers with rebuilt chevy cp3 pump (they do not sell new anymore)
used cp3 (working when I took it down) cummins cp3 (~90k miles)
fish tuning dual pump controller
new fp compounds, carillo rods, hamilton cam push rods and springs, etc

What are some things that I can check on this truck to troubleshoot / eliminate?
At this point I am willing to try just about anything.
Thanks in advance.
 
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They are brand new from exceedy. I suppose I could have them tested? but they sent the flow sheets with them so I assume they tested before they shipped? I also bought brand new injector tubes.
 
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Just an update on this thread, Dominic (Dom_c13b) was able to tune this truck and now it is running great!. Thanks Dominic@TenacityTuning
 
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