mm3 Variation

[FUBAR]

All right, I've been seeing some interesting information regarding mm3's that I would like some input on.

Data logging my EFI tunes, I keep seeing mm3 spike to a high number, and slowly or quickly taper off. How much? Varies by truck. Mine, usually 147mm3 @ a 2600uS @ 2800RPM down to 120mm3 @ 2800uS, 3600RPM. Never understood how mm3's could taper off if fuel pressure and uS are increasing. I understand mm3 is purely a reference of pressure and injector opening time, etc. So why do they taper off?

Now, here's a comparable that's interesting. Using my box tuner as a base file, torque limiter off, I ran my script over top of it, verify everything changed, here are the results: 162mm3 @ 2600uS @ 2800RPM UP to 183mm3 @ 2800uS @ 3600RPM. The truck felt much more powerful than my clean EFI tune(when I say "clean" I mean a box tune hasn't touched it.) Throttle response is more instantaneous, and the truck just feels like a frieght train also.

So, here's what I did, set my whole Pedal mm3 table 25% - 100% 30mm3 on each tune (clean EFI and box tune base file.) Here's what happened, clean EFI tune did limit me to 30mm3, Box tune base file with same script and settings as clean EFI tune limited to 98mm3 fueling 63mm3 more than I commanded. Multiplier? I don't know. But here's what I did to tame down the Box tune base file: I went from 25%TP @5mm3 and worked it up to a max of 120mm3 @ 100%TP. Throttle resonse still was instantaneous, but overall power was cut back.

I've heard around 145mm3 is considered WOT because of the mathmatics, but I don't believe so after about grenading my tranny and lookign in the logs.
Food for thought...I'd like to know what you guys think. Attached are 2 screen shots of the Clean EFI tune with my script written over it, and the other the Box tune as the base file with my script written over top of it.

-Andrew

11956

11943

[CIDRAUGHN]

Ive been wondering about this one as well. Ive seen mm3 go up to 170 or so, sometimes a bit higher, but then it falls back off.

[97singlecab]

im having the exact same issue on one truck I'm tuning. I'm also doing a manual trans truck right now that's holds 145mm3 perfectly through the whole run. I'm hoping the new tables released tonight help this. I'll now tomorrow I guess

[GMPX]

The ECM is using the mm3 as the means of controlling a lot of things, this was one of the area's we battled with when it came to limiters. Mysterious mm3 values being commanded. I did a special OS mod so we could log a lot of the mm3 values the ECM uses and this helped nail down the limiters. I don't think there is a multiplier as such, it will be another part of the code overriding the throttle table values. In your logs, do you have the PID 'CM.INJSTAT' "Injector Fueling Status"? If yes, you will probably see that change number as these unexpected mm3 values come and go.
If you have it, what number is that PID showing when the mm3 seems to have a mind of it's own? I can tell you, when it's at 12 it's trying to limit RPM.

[FUBAR]

Ross, nowhere in my log does "CM.INJSTAT" deviate from the value "0" It's always "0"

[2007 5.9]

I'll be performing the same test today with my box tune to verify the phenomenon.

Ross, I'll send you my files and log for you to look at if my truck does as Andrews does.

~Les

[Dmaxink]

Testing this as we speak also...

[2007 5.9]

So in some initial testing....my truck acts VERY different when running my DD tune scripted over my box tune.

Throttle sensitivity is increased substantially.

I'm going to try to log a run, but I'm nursing a patched boost boot until my new one arrives, so no wot runs.

~Les

[icem237]

I myself am seeing this , I tested with the same scenario as Andrew (Fubar). And according to my logs and the butt meter i get much more on he bottom to mid range! Definitey needs investigating. I will post logs in the next lil bit.

[AdamRRT]

Is it possible when the PID you're reading when mm3 is falling off inversely to pressure and duration increases, that the PID is actually reading mm3 as it correlates to RPM? And therefore you're eating more fuel per cylinder, just a little faster than your CP3 (or injector or whatever fuel system part is being read) can keep up? The thought in my head thinks back to how a certain amount of nitrous feels better at low RPM than at high RPM because you're burning it across more RPM. More torque when I spray at 3k rpm compared to 5500 rpm. Does that make any sense? Just a thought about why we could be seeing funny values. That's all. Had a few hours of drive time to ponder such issues. I'll try to meet with Phil (Bluecat) tomorrow and see what he comes up with, and update the discussion. I'm just really excited to see some progress. Seems a little stagnant this past little bit.

[FUBAR]

***Update

After talking, debating, testing, etc.. about this topic, I would like to inform what I have gatherered and best understand logically about this subject.

First and foremost, thank you to the testers who plugged this information in and used their expertise to best rationalize what's going on here. And also thanks to the folks who contributed to the thread with their expierence as well.

While the explanation I'm about to give is by no means an end all to end all, but hopefully a far better understanding.
Basically, after reviewing what the true pulse and pressure values were via custom maps, they were not adding up to the corresponding tune. They were..you guessed it..MORE!! Big shocker there huh? LOL. When Dmaxink took the info. gathered, plugged into a TRUE clean EFI tune, he was able to get the same results as the Box Tuner base file. That's pretty much it, but if you're like me, and have to analyze things, read on.

In comparing pedal mm3 Box Base file against true efi, the box base fueled a lot more. Now I think it is some sort of multiplier casuing, that, but it's probably actually not, but is to some degree. If you have more command more mm3, that is basically the grandfather to controlling the final values (how much) what the ECM uses to fuel. Elementary right? Think about it...Pedal quantity table. It was the Box tune programmers way of short cutting a crude way of tuning. Tune says it needs to fuel a bunch of mm3's early, well, guess where it's gonna look to in the table necessary to run? Fuel and pressure. It was those values that were highly elevated causing the effect. Nothing we really didn't know from the start. But now we're a bit better educated and, well, we TOO CAN do it in EFILive. Just a more sophisticated way, thanks Ross.

So, if anybody has another take on it, or a more detailed explanation of how the box tune programmer was changing it, by all means, this thread's always open for discussion.

-Andrew

[Dmaxink]

Nice explanation bud, glad it makes some sense...gotta love custom maps :rockon::cheers:

[2007 5.9]

Kory,

Readers digest version of setting up maps...I started one, but my values are all messed up.

~Les

[Dmaxink]

i just made a screen video (whatever it is called) and tried to post it, that didnt work..so i just tried to zip it and attatch and that didnt work either...ill email it to you les

[2007 5.9]

Wow!!!

Thats very helpful....good info to know!!

~Les

[comnrailpwr]

Would like to know aswell kory

thanks Jake

[Dmaxink]

I'm uploading the video to my site as we speak...so i will attach the link as soon as it is loaded. Les, you will get spoiled quickly with the maps! I use them daily

[2007 5.9]

Yes I can see being spoiled by them...already noticed variations that were news to me.

~Les