Power Commander 5 cruising MPG issue, And tuning questions plus my experiences so far - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
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post #1 of 43 Old 06-07-2016, 12:47 PM Thread Starter
Join Date: Mar 2016
Location: Austin Texas
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Power Commander 5 cruising MPG issue, And tuning questions plus my experiences so far

I had the low rpm downshift stall (rarely, but it happened 3 times in 1000 miles, which is FAR too often for my tastes) and the cough into the airbox (very VERY often, probably 75% of the time when starting off from a stop)

So I bought a PC5 to fix it. The bike hasn't stalled since and the cough into the airbox is gone. The bike feels stronger. I am running the off the shelf map for an otherwise stock bike right now, until I get a slip on.

I like the extra power, I love that the bike doesn't die or cough anymore, but I HATE having lost 10+ mpg at steady state highway cruising in the 65-80mph range.

I am fairly experienced with EFI tuning from my years as a Subaru guy, so I called Dynojet and confirmed what I suspected, that a 0 in a cell means ECU fueling, and any number is a direct % added or subtracted from there. Not really sure how it can nail down OEM fueling with the O2 sensors out of the picture, I am assuming it uses the base fuel tables in the ECU. Not ideal, but good enough for now. Ill add the autotuner later.

Looking at the map for an otherwise stock bike, there are HUGE percentages of fuel added in the 3500-4750 rpm ranges in the 15 and 20% throttle columns, which is where I am 99% sure I am when in the steady state 65-80mph highway cruising situation. The one cell has fully 20% more fuel than stock.

What I want to know is, WHY!!??? You don't need more power when you aren't accelerating, and as soon as you ask for more power by turning the throttle grip, you have moved out of those throttle % ranges.

I can't see any reason not to 0 out, or close to 0 out those cells. From what I can tell that should give me back the same MPG that the bike had stock in that situation or so I would think. The one cell in that are is adding TWENTY PERCENT fuel over stock. WTF for??? Dynojet couldn't give me a solid answer and even seemed slightly evasive when I asked why on earth would you do that lol. I gotta think there is a reason, but I can't think of wtf it would be. Unless the bike runs dangerously lean there.

I DO have one theory of why it MIGHT be that way.

If they have extra fuel there, that means there is more power to be made there over the stock fueling.
Which means if I load the bike up with some weight, or hit a slight hill, there will be more power there, reducing or eliminating the need to give it more throttle to maintain the same speed. That is the ONLY advantage I can think of.

Its not a case of "what if you want to smoothly accelerate to pass someone?" because when you twist the grip to do that, you will move out of those cells and their values become irrelevant.

I think I am going to go pull 5% across the board in the 10-15-20% throttle columns from 3000rpm to 5000rpm. That will still give me fueling over stock in many of the cells. If the cell has less than 5% added, I will only pull out what it has added so I don't go to less fueling than stock.

Ill report back after I do that.
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post #2 of 43 Old 06-07-2016, 07:30 PM
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Location: Thunder Bay, Ontario
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Interesting observation. I installed the PCFC with the map for arrow exhaust (I installed the map for the Arrow Header, and Arrow Exhaust in bank 2 for future upgrades). I too have noticed a decreased in MPG but I have not been keeping track. Keep me posted on what you find as I might want to tweak my map

2014 Suzuki DL1000 - Pearl White
2010 Honda VFR1200 - Candy Prominence Red
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post #3 of 43 Old 06-07-2016, 09:19 PM
Join Date: Jun 2015
Location: Berryville
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Thanks for the info! I have a PC3 on my Vulcan and love it. I regularly get high 40's into the low 50's MPG out of the Strom so am afraid to mess with it! I'll be watching your posts.
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post #4 of 43 Old 06-07-2016, 11:06 PM
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sounds like you have other issues going on?
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post #5 of 43 Old 06-07-2016, 11:22 PM Thread Starter
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Location: Austin Texas
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Originally Posted by kkchevy View Post
sounds like you have other issues going on?
What makes you say that?
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post #6 of 43 Old 06-07-2016, 11:24 PM Thread Starter
Join Date: Mar 2016
Location: Austin Texas
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And don't get me wrong, I know more performance generally brings a decrease in MPG. And I would expect that when ripping on it enjoying the new power. But light throttle steady state cruising, there is no reason the fueling needs to be any different than stock. I am going to hook the laptop up to it tomorrow and work on the map a bit, I don't want to just 0 that section out straightaway. I might 0 all throttle positions under 30% eventually though.

I just hate to have gone from 45ish mpg to 35ish mpg. And I know that reflects the entire tank so all throttle positions and RPM, but watching the meter when cruising I was always in the 42-44mpg range at those speeds now I am more like 31-32. I should be able to bring at least another 10-15 miles if not 20 out of a tank if I straighten out the fueling in that cruising range.
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post #7 of 43 Old 06-07-2016, 11:32 PM
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Location: SE Houston, TX
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Originally Posted by Wrathchild View Post
What makes you say that?
With a stock bike and appropriate map, that's way too much of a fuel economy drop. The "other issues" may be as simple as an incorrect map, which you plan on addressing. With a custom exhaust, dynoed, and running more than a little on the rich side, I only had a 6mpg drop with normal riding.

Not sure where you got your map, but most of the ones I've seen say, "Stock bike, with our without K&N." My guess has always been that the map accommodates the K&N and will be rich with a stock paper filter. I have zero data to back that up, BTW. It's just a guess.

Edit: The only way I ever saw a 10+ mpg drop from stock was if I was absolutely railing on the bike. I mean keeping it steadily over 6k and pinning the throttle out of turns. With the custom setup, that'd take me down to 32 mpg (I usually got ~44 stock).

2007 DL1000

Last edited by pinballer; 06-07-2016 at 11:36 PM.
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post #8 of 43 Old 06-08-2016, 02:10 AM
Join Date: Dec 2015
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On another red I talked about how horrible my mpg is. I wonder if I could get a power commander and lean it out in the cruising range that you mentioned? The Being a liquid cooled bike I wouldn't think it would cause any real damage as long as I don't lean it out too far. Thoughts?
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post #9 of 43 Old 06-08-2016, 10:42 AM
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Join Date: Dec 2013
Location: Maynardville TN
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A very nice trick I used with the PCV is to find a shop with a dyno, wire your PCV into the four way flasher switch, one position for each channel on the PCV. Run it in on the dyno giving you a custom map that is correct for your bike. Tune one channel for mpg and the other for performance. You can easily switch back and forth as need be. By using a dyno you get maps made for your bike, not just a generic map that gets you kind of close.
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post #10 of 43 Old 06-08-2016, 11:02 AM
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Join Date: May 2005
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It is fun to play around with the maps, I fine tuned my own with great results. One of my maps is still widely popular, and it performed great on my 1000 and for countless others.

BRIAN "GO Buckeyes, GO Wildcats"!

2015 DL650 XT "Hector"

1997 Honda Valkyrie 1500 custom “Dolores”

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