MM3 vs. PW?

[mstordahl]

I have been thinking about some things on my performance tune. I am commanding a max pw of 3200, but left the mm3 alone at 140 max, but would there be any bennefit to increasing the mm3 with the same pulse time? My instinct tells me no, but I am asking to those that have tried it and if it actually made any difference.

Thanks for any help.

[dansdieselp]

All mm3 is is a reference for other tables to go off of. Pedal position links to desired mm3. Then pulse, timing and rail etc take it from there. There really isn't any benefit to increasing mm3 unless you're trying to compensate for limiters coming into play beyond what EFILive has found in the ECM.

[mstordahl]

Right on, thanks! I thought that was all that it did, but was just wondering what the accepted method was so far.

[THEFERMANATOR]

One thing I've found with tuning the DMAX is on an LB7 the ECM will only command about 89MM3 of fuel yet teh tables go up to 100MM3 of fuel. I reworked it to use the 100MM3 of fuel value by adjusting my limiters and this gave me a better throttle feel byt being able to make finer adjustments. Also it allowed me to keep the bottem end lower in the fuel range and bring it on up high by playing with the torque tables. I'm not sure how your torque limiter tables work with the CUMMINS though.

[Stealthdiesel]

Likely a really basic question but isn't MM3 short for millimeters cubed which is a volume unit which is directly proportional to the pulse width signal sent to the injector?

So MM3 can be thought of as PW in the tables?

[AdamRRT]

Kind of. Yes of course it is cubic millimeters, and refers to volume of fuel. BUT we tell the ECM how much fuel it takes to deliver a given volume of fuel (mm3). mm3 is a representation of fuel volume, based upon rail pressure and duration tables.

Example (arbitrary numbers, accurate concept):
Stock you might have:
100MPa rail pressure + 1400uS = 100mm3

You then modify your duration table so that when the ECM commands 100mm3, it refers to the tables and gets 100MPa + 1800uS (up from 1400).

Note: I say to modify duration because I believe that we should set our rail pressure at the lowest levels that still perform well in order to reduce internal injector erosion. So I set MPa and leave it alone.

[tinman]

So really we should be upping the Duration for more power? I've been looking at another popular programmer and as best I can tell all it does to up the power is increase the commanded fuel on the tps tables and the pulse tables are the same as stock. I don't really under stand how this would work since all the other tables only go to the stock 140 max commanded fuel. So how does the ecm figure timing, pulse etc. at 200mm3 of commanded fuel if the tables don't go that high?

[GMPX]

So how does the ecm figure timing, pulse etc. at 200mm3 of commanded fuel if the tables don't go that high?
It doesn't, it only references the table to the final value of the axis then it's limited to that.

[tinman]

Well what am I missing. How does this other programmer make power if all the tables still only go to 140?

[olboyowl]

higher timing and fuel pressure would be my guess

[AdamRRT]

Simple. It is using tables that we don't have access to. You didn't think you're seeing EVERYTHING did you?

[THEFERMANATOR]

Also some tuners will use limiters that EFILIVE doesn't use, and simply max them out. Some tuners do things differently than EFILIVE does when they use there software to crack the ECM code. Many times there method doesn't really give much more HP, but makes it feel that way by taking away your useable throttle and making it touchy which many times gives you the allusion of having a big tune when in reality it is just poor tuning.

[tinman]

Ahh... Not seeing the forest for the trees. Thanks.

[AdamRRT]

Plus it's not an issue of mm3. Remember mm3 is just a value like X. We tell the ECM the amount of duration and pressure needed for a given mm3. So Smarty modifies duration & pressure tables we aren't seeing.

We know it truly does this and not just changes the feel. Many if us have put Smarty tunes on dynos. They make power for sure. Plus you can see what it's commanding if you log the data.