Anyone running custom tunes with diesel/propane?

[mark rinker]

Considering a purchase of EFI Live - wondering if anyone here has a developed an LB7 tune intended to be stacked with propane injection.

I have installed the MSD Digital Propane Injection system on an otherwise stock 2001 2500HD used for hotshot hauling with a 25' gooseneck trailer. Results so far have been very good.

My goals for tweaking the LB7 maps are twofold:

1) An everyday tow setting with optimal 'dual fuel' economy as the goal;

2) A max-power dual fuel setting for truck pulling.

Data gathered so far leads me to believe that both fuel maps (LB7 and MSD) will need to better 'coordinated' for best results, or at least some additional boost dialed in when the MSD system is enabled to burn the extra LPG fuel more efficiently.

Any info/opinions are greatly appreciated!

[GMC-2002-Dmax]

LP adds timing, the timing tables would need to be altered for continual propane use.

The drawback is less timing without the propane being used will give you less performance than you would otherwise get with the additional timing on fuel only.

You can only get so much HP/TQ before EGT's get out of hand especially while towing.

good Luck,

T NY

[mark rinker]

Hmmm...let me see if I understand your post...

LP (needs/wants) more timing to burn efficiently, right? The addition of the fuel itself doesn't alter timing, correct?

Agreed on the EGTs. Stacked with more fuel (Predator tune) you can get to 1800 degrees. Towing with moderate dual fuel rates has been surprisingly cool - mostly in the 700s.

[Elowe65]

Mark,

I think he means that adding LP changes/alters the timing as it burns faster (burns faster therefore advancing the timing from where its set at via the ECU). Therefore, you would back off the timing when using the LP.

By backing off the timing though, when not using the LP, the performance (just on diesel) will suffer.

Once the DSP2 comes out, you might be able to wire it up so that when the LP is activated, you switch the ECU to a different (or LP use) table/map. Then when the LP is turned off, the ECU will be switched back to a non-LP table/map.

[GMC-2002-Dmax]

Exactly,

Propane will cause the burn rate to accelerate, so if you have timing set and then add propane you run the risk of timing rattle or detonation which is no good.

So the trade off is less fuel only performance due to decreased timing.

Although the DSP2 O.S. would allow you to swap between two tunes, one for fuel only and one for both fuel and propane.

T NY

[mark rinker]

Now I have it. Thanks for the input. Another good reason for EFI Live.

The MSD system ships with a default fuel map setting of '100%', meaning that there are no user definable parameters in the software to increase the propane flow beyond the factory default, only decrease it from the 100% setting. You an also raise the boost pressure that it comes in at -which factory defaults to 1lb or 'ON' under almost all throttle conditions. You can also set max RPM and max boost limits on the propane.

I have run it stacked with 150hp Predator tune, coming on at 1lbs boost and droppping out at 20lbs boost or 3500rpms. Its smooth, linear, and no rattle at all, maybe even quieter than fuel only and a lot less smoke.

[Elowe65]

There are ways to alter the MSD maps to a certain extent, but you have to be careful.

[GMC-2002-Dmax]

I hope you have a stout transmission to handle that.......if not I see a new transmission in your near future.

T NY

[mark rinker]

Yep. My curiousity is satisified, and the perma-grin etched on my face!!!

Now back to the task of finding a good tow setting, and making some money.

Thanks again for the suggestions re the timing mods.

[mark rinker]

Nine months of running the MSD digital propane system with various fuel and boost rates has taught me alot. I have over 40K miles on the odometer since, roughly half are loaded towing miles with propane flowing. No issues with system or truck - towed a 29', 12K# boat on a triple axle trailer from Oakland, CA to Anchorage, AK up the Alcan - burning propane all the way in high proportions to offset Canadian diesel prices. What a trip!

Initially, I ran the system at its default setting of '100', a relative setting of maximum allowed propane flow to diesel. The power was awesome, but overall dual fuel consumption higher than necessary, even when extra boost added with a KD boost valve. Over time, a setting of '15' yielded a fairly consistent 4:1 ratio of diesel to propane, good power, and an overall savings in combined fuel cost for about the same MPG.

My plan is to use EFI-Live to develop a custom 'switchable' tune to alter timing - but only when the MSD system is actually flowing propane, not just when its active. This might only be while climbing a hill loaded, and then base timing would return rolling down the other side when propane is pulled. This is possible as MSD triggers off boost and throttle position - a 12V signal is available when the main propane solenoid is opened.

Also, economy when burning propane and diesel is a function of their relative costs/gallon. It would be ideal to have a system that would allow the user to enter the cost per gallon of each fuel on board, and let the tune determine the optimum ratio burned based on power requested, load, boost, etc. That might be a ways off - and only possible if you could dynamically alter the MSD tables. Right now, you select a number, and thats what you get until you change the number and flash it to the MSD ECU. (This can be done realtime from the cab/PC, without stopping, but who wants to carry a PC around?)

Any ideas? Superchips now markets the MSD digital propane system, but my understanding is that MSD is still supporting it. Anyone know what technology is used in the MSD ECU and Windows software? http://www.superchips.com/products.phtml?cat=24