Startup surge/Rev

[rbp4u]

Ive done all the searching and Googling that I can, and have yet to see where anyone has addressed it. Curious if anyone has been able to tame the 07-09 6.7 rev at startup.

I find it very annoying that every time I start the truck it sounds like I had my foot on the throttle. I have tried adjusting the crank timing but it didn't help, something still is commanding lots of PW while cranking?

Specific truck I am working on is a 08 6.7 Auto

[Move'n Up]

Post your tune

[rbp4u]

When I get home I will post it, but every 3rd gen 6.7 I have heard that is EFI tuned does it. Three trucks with different efi tuners all do the same thing. Its not some random issue I am having.

[KhakiCummins]

How much surge/rev are you talking? I have an 08 6.7L manual and do my own tuning plus have tunes from two other tuners and none of the tunes I have surge/rev on startup.

[rbp4u]

I will post up a video of it tomorrow, but the truck revs to between 1000-1200 rpm once it fires, then idles at 650-700. Where as my 2011 just goes to 700 when started.

[cindy@efilive]

If you're wanting people to help, post your data log rather than a video.

Cheers
Cindy


Sent from my iPad using Tapatalk

[rbp4u]

Here is the data log of start up, along with the tune. "Its not some random issue I am having. " Also re-read this and kinda thought this came off sounding like an a-hole, and that wasn't my intent. Was simply stating that every 3rd gen 6.7 I have heard start up has this same rev, and it seems to be the same no matter who's tuning it is. This is just my experience/observation.

19498

19499

[Move'n Up]

Yes you get a jump of Actual fuel pressure above desired and a huge spike in main duration right at start up.

Is this a fairly stock truck?

[rbp4u]

Truck is "stock" only has a cold air intake, egr/cvv delete, 5 inch exhaust.

I noticed the duration spike, but cant determine whats causing it. Since I had heard other trucks do the same thing I figured this was a common issue that guys were dealing with or was "stock" in the tune somewhere.

[rbp4u]

Thought about it all night, tried adding a boost based fuel limiter, (A9117) hoping it would stop the 60mm3 command but it did not. Still starts the exact same way. Any other ideas?

[Move'n Up]

I haven't had a chance to spend time looking through your tune but in the mean time, what happens if you flash in a stock tune?

BTW - I assume this happens in any CSP5 switch position?

[SASDakota]

Thought about it all night, tried adding a boost based fuel limiter, (A9117) hoping it would stop the 60mm3 command but it did not. Still starts the exact same way. Any other ideas?

I have a 3rd gen 6.7 coming out for an update flash this evening I'll look at this on his truck (total emissions intact) for comparison.

[SASDakota]

Also, Take note Pilot qty hit 12.2mm3 & 911us to go with 68mm3 and 2400us of main... That is a lot of start up fuel. I just browsed the log real quick didnt have time to understand what its telling me but seems off the cuff that there are some adders in play here.

[rbp4u]

I'm fresh outta ideas here. I have looked through every map and haven't had any luck. I thought for a while that it was a fuel pressure related issue but still don't know how fuel pressure could effect the the commanded pulse width in a way that would cause it to be that high. I have another 6.7 coming in tomorrow I am going to data log before I tune it and see if it does the same thing. I will post that log once I have it.

The tune I am using is one from tune file depot, there is no other tuning or foolers on the truck.

The truck did do the exact same thing prior to me tuning it, and it was flashed at that point with a file from calibrated power, just for reference. I am surprised that it seems no one else has seen this before. I really didn't think it was an isolated incident.

[Dom_c13b]

I've got a truck that does the same thing. Didn't think anything of it, thought they all did it. Curious to see if anyone comes up with anything. The truck did it stock, we just deleted it and tuned it and it still does it.

[Move'n Up]

Ever get this figured out?

[rbp4u]

Nope, its beyond my current knowledge level haha. I am still assuming every truck does it, and most folks just aren't worried about it. Its not really an issue to be concerned with, its only annoying in my mind and id rather not have it sound like "HEY LOOK AT ME" every time the truck is started.

I would assume though that if the truck had a big set of injectors in it, the star-up surge would be quite large based on the amount of duration it requests.

[SASDakota]

The 3rd gen 6.7 I tuned for one of my wheelin buddies has all emissions equipment on it just minor tweaks for towing and it has the same startup RPM. I don't consider this an "issue" it is merely a designed startup cycle.