2011 6.7, just deleted, now sporadic surge?

Cummins_Bred

Cummins_Bred

Cummins R&D Tech
Joined
Mar 31, 2011
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451
So finally got the DPF off my truck yesterday. LOVE the sound of the flo~pro, love the H&S pull in the hotter tunes. I have unplugged the egr valves and throttle valve. But under heavy acceleration I get a nasty quick surge or almost like a harsh miss sometimes. Ideas? It's got me fairly confused. Drives well around town under light to moderate throttle, but 3/4 throttle or more, smooth application or stabbing it, it randomly will surge once/twice before i back out of it. I thought it was the clutch slipping at first, but i watched the tach the next time and the rpm dropped with the surge, instead of revving up a bit. I'm open to ideas/suggestions, because unless it's something I can't see in the tuning, no idea what might be causing my issue
 
Are you positive its not the clutch slipping? I know you said you watched the tach but right after i did my deletes with only 4 or 5k miles on the truck my stock clutch would slip on the mild tune. Not everytime but it would. Put it on wild or hot and forget about it the clutch would slip for days. Didnt happen to turn off torque management did you? Tried that as well one time and that seemed to almost replicate a clutch slip situation. Only other thing i could think of is watch your rail pressure. Wondering if your popping the relieve valve on the rail?
 
That is possible. Don't have my gauges in yet (Just wanted better fuel eco now), so it's possible i could have popped the dump valve. I did not disable torque management. And i knew the higher tunes would murder the clutch, but this really seems like a hesitation, not slip. Almost like throttle drops to zero for a split second then right back up
 
What's the build date on your truck? Monitor load and torque. I bet you see it drop to zero when this happens. I know the 12's will defuel when they detect clutch slippage.

A 30hp Smarty tune will slip the clutch on a 6.7. I can pretty much guarantee you're slipping it
 
it's a late '10 built, 2011. I didn't know the truck could sense slip in the manual? i would think it could in the autos but wouldn't think they'd have sensors in the manual trans for that. How would i monitor load/torque? I haven't set up my mini maxx display yet, is it an option I can see there?
 
I would have to say your slipping the clutch bc you dont pop the rail valve till 27000 im pretty sure
 
Well I was sure i was slipping it day one, then driving it yesterday afternoon, I was sure it was a surge or cutting out briefly or something, after last night I'm almost back to it just being the clutch. Torque never reads any number, and load went down slightly when it jerks, but the tach jumped up when this happened. Idk. I'll probably just throw a clutch in it here shortly, I need one no matter what this issue winds up being, and see if that cures it. If so, I suck at reading what the truck is doing. If it doesn't, i'll be doing more investigating of the tuner. If I baby it in the "stock" tune it drives fine, so i'll live with that for now
 
be aware the "stock" tune with default timing creates excessive cylinder pressure due to a static timing map used across all levels

get a clutch in it and crank it up
 
Apparently someone has something against the goodness of a napa clutch! Haha


He could also adjust his timing to run a mild or no power tune. Timing on 2 with the mild setting would be a safe bet. Dont mash it and the clutch wont slip. A little bit of foot control will make it last until you get a DD
 
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diesel_importer said:
Forrest uses Napa Gold clutches and swears by em.......... I swear.
Click to expand...

Forrest is also the same guy that pulled up at my shop in a red 98 12V (The Unicorn) with a new design down the side of his truck because he thought 5-600 HP was fine on a stock HG. :charger:

Just ribbing ya Forrest. We knocked that b!tch out and got back down the road.

To the rest of ya, don't hate the NAPA Gold!

:kick:
 
And Forrest knows his stuff about that H&S.

If you're going to run it on "stock" to save your clutch, you're probably better off pulling the H&S until you're ready or back down the timing if that's possible.

I don't know much about the tuning in the H&S. So I'm just going off of Forrest's statement.
But I do know that I wouldn't want a ton of timing in a motor without the fuel to match, and that's what it sounds like Forrest is getting at.
 
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First NV4500 I pulled, I borrowed Forrest's transmission jack. I have never felt that uncomfortable with a heavy object over me. Not before that, or ever since! First pic below. :bang I'm just dang glad I wasn't pulling a 5600.

If you're doing it on jackstands, then spend a few bucks more and go with something like the second pic. For the money its not bad and you'll feel comfortable enough using it, plus it'll have tilt and roll adjustment that actually works :poke: Lots of companies are out there. From $125-$1000. The $125-$150 dollar ones will do fine if you're not looking to be doing them all the time.


image_11238.jpg


ATD-7436.jpg
 
I pull 5600 several times with a floor Jack and 15" brake roter. Works pretty good but not as good as a tranny Jack.
 
ComnRailPwr said:
I pull 5600 several times with a floor Jack and 15" brake roter. Works pretty good but not as good as a tranny Jack.
Click to expand...

Another viable option. A buddy does his 4L80's that way in his 4th gen Camaro racer.

Then again another buddy puts his 400 on his chest as he lays on a creeper and just presses it into place! I keep waiting for him to drop a converter out.

I spent about $200 on mine and it paid for itself the first time I had a stubborn transmission. The tilt and lean with the ability to push on the jack or the transmission without worry of one moving without the other and the tranny come crashing down; makes it a much safer one man job.
 
I appreciate all the advice, especially on the not running the stockish tune. When I do the clutch, I may just do it over a weekend along with the headstuds and valve springs
 
So,I had lots of time to play with the truck this weekend, and hauled a small trailer yesterday. It is the clutch, i'm just paranpoid. On a related but totally different note... Holy fuel economy batman!!! Soooo much better!
 
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