Why can't I achieve full fueling at higher RPM?

[B00STJUNKY]

Anybody have some advice for me as to why I am unable to hold my commanded fuel? I was starting to think there must be a limiter parameter/table that was not accessible in the VCM Editor for my OS, but upon submitting a ticket to Support @ HPTuners, they assure me that it is a tuning issue, but didn't give any hints as to what I'm missing.

I am commanding as much as 185 mm3 from my pedal table and pulling a bit past 4k RPM, but I notice I am never achieving that fuel rate, and am consistently dropping mm3 throughout nearly the entire RPM range.

I am including a log file. Any help would be greatly appreciated. Thanks!

5k_v6.6.hpl

[Moparmatty]

The response you got from HPT is indeed correct. It is not a software issue.

Your data log shows what is controlling the drop in mm3.

Why are you trying to command much more than 140mm3? The HSG tops out at 160mm3 and the pulse and fuel pressure tables aren't scaled any higher than 140mm3.

[steve05ram360]

Doesnt the pressure map scale need to be mapped out to the higher 185mm3 value? Or is the last table row entry carried out to higher axis values?

to me it looks like the all speed gov is under control...

[Turbo_Mike]

The response you got from HPT is indeed correct. It is not a software issue.

Your data log shows what is controlling the drop in mm3.

Why are you trying to command much more than 140mm3? The HSG tops out at 160mm3 and the pulse and fuel pressure tables aren't scaled any higher than 140mm3.

It seems to be a sort of common theme to command more fuel than you can possibly run so that when the limiters and governors try to stomp on it, you still get full fuel for longer than you would have.

[Turbo_Mike]

Doesnt the pressure map scale need to be mapped out to the higher 185mm3 value? Or is the last table row entry carried out to higher axis values?

to me it looks like the all speed gov is under control...

If you exceed the scale of any table, it maintains the value of the last row/column, correct.

[Moparmatty]

Doesnt the pressure map scale need to be mapped out to the higher 185mm3 value? Or is the last table row entry carried out to higher axis values?

to me it looks like the all speed gov is under control...

Why go to the trouble of rescaling past the 140mm3 though?

[B00STJUNKY]

I've tried it both ways, commanding up to 140, and 185. I am well aware I won't get anymore fueling beyond the last defined mm3 column, but it was a last ditch effort to command more than maximum to see if it would help.

Moparmatty, do you have a suggestion as to what I should be looking into?

Am I missing something in a table, or is it a single parameter?

[Moparmatty]

I've tried it both ways, commanding up to 140, and 185. I am well aware I won't get anymore fueling beyond the last defined mm3 column, but it was a last ditch effort to command more than Max to see if it would help.

Moparmatty, do you have a suggestion as to what I should be looking into?

What does your log tell you the cause of the mm3 drop is?

[B00STJUNKY]

All speed (normal) is what is limiting fuel.

I see some droop parameters and have tried zeroing those out. That was a bad result (runaway condition).

I've zero'd out some of the Fuel Decrement, just not the threshold parameters.

I've been eyeballing the Deceleration parameters, but keep telling myself those must surely be for when you are decelerating (ie. no throttle), so I've not tried messing with those yet.

[steve05ram360]

If you exceed the scale of any table, it maintains the value of the last row/column, correct.

Thanks...

Why go to the trouble of rescaling past the 140mm3 though?

I was not sure if the last row was maintained or not, hadn't figured that out yet. Rescaling allows for finer control if needed. I did this on 2 maybe 3 tables so far, the one that comes to mind is the pedal map. Tweeked it to match my goals and driving style. Another one is the baro correction, I had no idea the small fluctuations in pressure changes performance the way it does.

[JohnnyK05]

PM sent.

[Dom_c13b]

Go to engine, fuel, all speed gov is at the bottom. Bring it up to 7000 on all 3. You may have to bring it up higher, it should start pulling fuel way higher than before. The description says to set it to desired max rpm.. but I don't buy into that. It's a pid limiter that will pull fuel until you reach that rpm, just set it way above. You should then have full fuel to what ever you set you cut out at. I like to use the other limiters to pull fuel, such as the boost limited fuel table, and the throttle tables.

[Dom_c13b]

Also, you're going to need a lot more timing up top in order to make any power in the higher rpm.

[B00STJUNKY]

Go to engine, fuel, all speed gov is at the bottom. Bring it up to 7000 on all 3. You may have to bring it up higher, it should start pulling fuel way higher than before. The description says to set it to desired max rpm.. but I don't buy into that. It's a pid limiter that will pull fuel until you reach that rpm, just set it way above. You should then have full fuel to what ever you set you cut out at. I like to use the other limiters to pull fuel, such as the boost limited fuel table, and the throttle tables.

Thank you. I had one other individual from this forum PM me with similar info. You guys are awesome. I much appreciate it.

Those RPM limit descriptions are VERY misleading. Not only in saying to set them to your desired cutoff point, but also in stating that they are specific to manual transmission calibrations. My truck is an automatic, so I hadn't put much thought into them.

Also, you're going to need a lot more timing up top in order to make any power in the higher rpm.

Wow, I thought I was already getting close to the limits of how far I could advance my timing. I've always heard no more than 32* advance as a general rule of thumb.

Do you have another take on that?

Again, thank you very much for the advice, fellas. I'll give this a try as soon as the bad weather breaks.

[Dom_c13b]

32 is a good number to use for a stock truck, stockish rpm. When I get a chance to get back on my laptop I'll check to get exact numbers, but on my 5k rpm tunes I'm up in the 40+ range. At 4k I'm usually around 38+ depending on duration obviously. I also shut injection off at 23* atdc.. after that it just seems to make heat and smoke. May be able to get away with more on a stockish truck turning lower rpm but with big injectors turning high rpm that's a good stopping point.

[Bdubbz]

Great info, thank you for sharing

[paulb]

From looking at your log, more then likely that All Speed Gov. B is the main one that is doing your limiting. On my truck setting it less the 5500, will pull fuel away. I normally have it set to 8000.

Paul

[muz79]

SOI in the late 30's early 40's wouldn't apply to 143* injectors though would it?

[B00STJUNKY]

Dom, Paul, and Johnny, thank you very, VERY much for your contribution. You three have already provided more helpful insight and information in a mere 3 or so posts than this entire diesel forum has provided in the last year or so.

Kind of frustrating to have guys tell you that your issue lies within your tune and somewhat lead you on as if they might be helpful, only to leave you hanging when the answer was seemingly right at their fingertips.

I've been chasing full fueling up past 3200 RPM for the better part of a year, and the only other person who has been helpful in the journey to getting there has been Les from Silver Bullet, who ironically tunes diesels for a living, and would thus have the most to lose by sharing knowledge.

Again, thank you guys very much. Now, it would be nice and helpful for others who take on their own projects if HP Tuners would update their definitions for the AllSpeed RPM limits so that they aren't so misleading.

[Dom_c13b]

I went through the same thing when I started tuning 3-4 years ago with Efi-Live. It was very much the same, I'd read til my eyes bled and couldn't figure out the full fueling over 2900rpm. I'd get to a point in a post where the person would figure it out and then it was crickets' no one would point to where it was. I finally figured it out a couple years ago while just trying something on my truck and it worked.
I'm a hobbiest tuner, I've tuned a handful of local trucks and my trucks for a while now with great sucess. I was always so frusterated trying to figure stuff out that I said I'd do my best to help others when I could. That being said, I still flash my truck 5+ times a week probably. Always trying new stuff.
There were a few efi-live guys that were very helpful in the begininng and Les was one of them, he's given a lot to the diesel tuning community.