Surging on cruise/ light throttle

[CIDRAUGHN]

Doing some tuning for a friend I have come across a problem. It is not in the tuning as I have exhausted that option. I have put a completely stock tune on it and countless other tunes that have worked well on previous customer's trucks. I know this is not a tuning issue, since a stock file does it as well, however I was hoping someone else may have ran across this problem before, and know how to tune it out. If you put the truck on cruise at around 2200 rpm, it does fine until the cruise backs off going down a hill. When cruise brings fuel back in to maintain speed it bucks and surges pretty violently. It also does it, but not nearly as bad, when regulating speed with your foot.

Now on to the truck, it is nearly stock, other than programming, 180hp injectors, arson 3 kit on the cp3 and a few other things that wouldn't really make a difference like clutch...etc.

Any help would be appreciated. I have logged the truck on every file, and you can see the rail and mm3 surge with the truck, but I cannot find what is causing it. I am starting to wonder if it could be in the FCA but have no way of confirming, as commanded DC and actual DC are staying in line.

Thanks in advance.

[cumminsDK]

I have the same problem with an 07. It also has bigger injectors and a street cam and is a 6sp manual. I run the same injectors in my truck (automatic) with no issues. I believe it is pulse map related and haven't had enough time to completely fix it. I have helped it by adjusting the pulse map. While recording (red button) pulse and pressure and mm3 open tune file with highlighting on and see where you're at in the tune file while it happens. Try smoothing in these tables first and also make the pulse numbers closer together instead of big jumps in microseconds from one cell to the next!

[CIDRAUGHN]

Thanks for the reply. I have been over every spot in the pulse map to try and find an abnormal jump, even tried raising the pulse in those areas to make it stay in that pulse pressure and mpa instead of jumping to the next column. Of course I smoothed out each time. Come to think of it, this is also an 07 manual. Do you think that by chance it may be an OS issue?

[2007 5.9]

Pressure table...same idea as the pulse table...possibly a largish jump in pressure where this is happening?

[CIDRAUGHN]

Just checked the pressure table and it looks good too. I have pressure kind of flattening out at the cruising range, just because I dont like to see it fluctuating much with slight variations in mm3. Then when leaving the cruising range, it gradually moves up or down from there. I do know that injector rattle is terrible with factory pilot tables on this truck, worse than most I have seen. This is the 2nd set of 180s that have been in this truck. The first set balanced terribly, and we sent them back to be re-worked. Builder(s) said nothing was wrong with them, but magically when we got them back, they balanced dramatically better.

By the way, thanks for the great ideas guys, keep them coming as the truck is terrible when it is doing this, especially when towing.

[2007 5.9]

So have you changed pilot timing/quantity tables then?

[CIDRAUGHN]

Yes, but only slightly. The noise got much quieter. Not all the way gone, but quieter than a stock 03-05. I had something to go by with my truck having similar sized injectors, and it has no rattle at all. The reason I was referencing the factory pilot tables is that we hadn't had the stock file on it in quite some time, and we put it back on the other night to try and confirm whether it was tuning or hardware or both related.

I had this surge in mine when EFILive first came out for the Dodges, but I was able to resolve it pretty quickly in the main pulse table. I have even scripted my street tune on to his factory file to compare. Same thing every time. Sorry for the long posts guys, just trying to be as detailed as possible.

[2007 5.9]

Would you be willing to toss in a test tune to see if it's indeed tuning or hard parts?

[CIDRAUGHN]

Absolutely. Truck is 07, 180 hp injectors, stock turbo, Air Dog, Arson 3. Ill email you a stock file.

[2007 5.9]

Send it away

[CIDRAUGHN]

Thank you sir. Will be seeing him tomorrow and I will let you know how it does.

[2007 5.9]

Very well...hope it good news

[2007 5.9]

Bump....any feedback?

[CIDRAUGHN]

Sorry, internet connection went down last night and just got it back up. However, the surging was the same as before. I have managed to minimize it while driving with your foot, but it is still very violent with the cruise activated around 2200 RPM.

[2007 5.9]

Damn...weird.

[CIDRAUGHN]

Oh well. Im starting to lean toward the injectors (which I don't think have ever been right) or the FCA in the pump.

[2007 5.9]

I'd look at FCA.

[cumminsDK]

Modded FCA's...those never have issues! SMH

[KB3MMX]

Bigger Injectors are adding extra fuel compared to stock at the same pulse.

Go to the main injection table and highlight everything from about 60mm3 and less then put -20 in the upper box and hit "%".

You want to drop the fuel (pw) in the first half of the main table to reduce the jerking. If it's still not enough, do the same thing again by 5% each time until it's happy.

[CIDRAUGHN]

I have tried doing that as well. For me that has only made the surging worse, but who knows, we will see.

[KB3MMX]

Thanks for the reply. I have been over every spot in the pulse map to try and find an abnormal jump, even tried raising the pulse in those areas to make it stay in that pulse pressure and mpa instead of jumping to the next column. Of course I smoothed out each time. Come to think of it, this is also an 07 manual. Do you think that by chance it may be an OS issue?

You said you tried raising pulse, that'll make it worse.
It needs to be reduced until.it's happy, it's a commanded fuel problem...too much too quick

If you don't mind sending me the tune, I can do some adjustments to try..

[dpc]

Bringing this back up, I have an 06 that does the exact same thing. Did you ever figure out the problem? Thanks

[cumminsDK]

I haven't seen the truck I was having issues with for awhile so no progress here, however I must eat some crow on my modded FCA comment above! I have installed an arson III kit from Shane at Motorsport Diesel in a new pump and installed it on my truck and WOW! It performs above expectation and flawlessly! Ok sorry for the derail.

[mvwwld4u]

I