Power Commander problem?

[All4beans]

Here's my setup:

- 2007 13A

- Two Brothers slip-ons

- Stock air box with K&N

- Power Commander III USB running map for the two Bros from PC website

A few weeks ago, I read on this forum that most folks disconnect the stock O2 sensor when they install a PC on the FJR. So to verify I contacted Dynojet and they said same "Yes, disconnect O2" they said as long as I don't get an error from bike because it's disconnected I should be fine.

Well....immediately after disconnecting the O2 my gas milage went straight in the "crapper".

Before with the PC and the stock O2 sensor both connected I was getting 47-50mpg consistently across all types of riding conditions. Suddenly now I was only getting 41-42mpg.

So I hooked the O2 sensor backup, rode another tank of gas but it did not go back to the original milage. I even tried "leaning" out the PC to save a little juice but nothing seems to make a difference now.

I called Dynojet to see if they had any ideas but they were no help at all.

Has anyone out the experienced this before? I'm at a loss now because I've tried everything I can think of and nothing seems to work.

Any ideas?

 

[UselessPickles]

Your PCIII and your O2 sensor are both working as designed. Probably nothing is wrong.

With the O2 sensor plugged in, your bike will enter "closed loop" mode while cruising and other light throttle conditions, which means the O2 sensor will be used to run the bike at 14.7:1 AFR. The PCIII cannot work around this. If the PCIII calls for more fuel, the bike will just offset it to achieve the 14.7:1 AFR based on the O2 sensor.

The PCIII does add more fuel in much of the partial throttle and cruising areas. This is what smooths out throttle control. If you unplug the O2 sensor, then the PCIII will be free to add fuel without being overridden by the closed loop system. Smoother throttle, but more fuel. It's up to you to decide if it's worthwhile.

BTW - don't trust the MPG display on the dashboard when running a PCIII or anything else that intercepts and alters the injection signals. You have to calculate MPG the old fashioned way.

 

[JamesK]

I am guessing that somehow the O2 sensor is still not in the circuit. As a test why don't you by-pass the PC by plugging the original ECU plugs back together? Depending on your PC map, 42ish MPG is not that uncommon. You could try loading up the UselessPickles Modified Smoothness map, it offers a good compromise b/w good MPG and performance and seems to run well on most setups. For example, my setup is Blueflame Performance Oval slip-ons, Uni filter, opened up Air box and removed PAIR system, and of course disconnected O2 sensor. Hwy slabbing at a fall a sleep speed (not common), i can get high 40s MPG, but unfortunately typically I am in WOT as much as possible, so the MPG can go down to mid 30s.

 

[ScottyUSN]

No help other than your after install MPG sounds more normal than your before install mileage. I'm doing good to see low to mid 40's.

I've also read PCIII users experience around 3-5 mpg decrease (depending on which map is used).

How can your mileage not vary as result of riding conditions (commute, highway, twisties)? That does not sound like a reasonable an expectation.

 

[olsonm3915]

Before with the PC and the stock O2 sensor both connected I was getting 47-50mpg consistently across all types of riding

You weren't actually getting that mileage. The bike's computer THOUGHT you were, based on the injector pulse widths it was sending out. But in fact the actual pulse widths delivered to the injectors by the PC III were longer, hence your true mileage was probably in the low 40s. This is no mystery, but in order to understand why this happens you have to understand the basic fundamentals of how fuel injection works and how the MPG computer calculates mileage. If you really want to know what your mileage is, simply use the trip meter and the gallons displayed on the gas pump, just like the old days.

Useless Pickles has every fact you need in his post, read it and take it to heart.

 

[UselessPickles]

You could try loading up the UselessPickles Modified Smoothness map, it offers a good compromise b/w good MPG and performance and seems to run well on most setups.

The smoothness map is intended for use with a stock bike. Also, it was not tuned to compromise between MPG and performance. It was tuned purely for smoothness, which means it's probably running richer than the maps from Dynojet, which actually do run a bit leaner at partial throttle (I think it's ~13.8:1 vs 13.2:1 at full throttle). I believe the smoothness map was tuned for 13.2-13.4:1, but I'm too lazy to lookup the web page that describes it.

 

[wfooshee]

+1 on don't believe the dash for MPG. Calculate it at fill-ups.

When the bike is getting feedback from the O2 sensor, it will counter-act the PCIII's richening of the mixture by leaning it out further, to zero in on a "correct" reading from the O2 sensor. This will be a lean mixture as far as the ECU is concerned, and will increase its displayed MPG. Doesnt run closed loop all the time, so I can't say how much of a difference from actual to expect.

There is also the possibility that you've coincided with winter fuel delivery to your area, which is usually a lower MPG also, without anything changing anywhere else.

 

[JamesK]

You could try loading up the UselessPickles Modified Smoothness map, it offers a good compromise b/w good MPG and performance and seems to run well on most setups.

The smoothness map is intended for use with a stock bike. Also, it was not tuned to compromise between MPG and performance. It was tuned purely for smoothness, which means it's probably running richer than the maps from Dynojet, which actually do run a bit leaner at partial throttle (I think it's ~13.8:1 vs 13.2:1 at full throttle). I believe the smoothness map was tuned for 13.2-13.4:1, but I'm too lazy to lookup the web page that describes it.

Thanks UP, however you "tweaked" it, that map seems to offer the best performance/MPG of any of the other maps I've tried with my setup, short of going through a dedicated Dyno mapping session.

 

[All4beans]

All, thanks for the replies and inputs. I guess there are many factors that could be affecting this situation. I did forget to mention it in my original post but the MPG I gave were from calculating it at the pump with the trip meter, not the bike display. The bike was regularly telling me I got 55 MPG which I knew could not be correct.

When I hooked up the PCIII it started reading that kind of MPG but when I did the math it was always off by at least 7-8 MPG.

What about this; in an attempt to verify nothing is broken I had considered removing the PCIII and returning the ECU and O2 sensor to stock configuration but that's a lot of work

So, is simply putting a "Zero" map in the PCIII and hooking the O2 sensor back up the same as removing the PCIII?

I swear I use to get 105-115 miles on the first half tank of gas but now I'm lucky to get 85-90 miles.

 

[JamesK]

The other factor is the altitude, remember getting awesome mpg in CO. Also whether the gas you were running had that crap Ethanol added, since that is almost a direct 10%+ decrease in usable fuel.

 

[El Cajone]

Comparing mileage (measuring with pump and odometer) between a couple of long trips (1000mi. +) before and after my PC III install, I found that my mileage decreased by about 10% with the PC III. That's with a stock set up, O2 sensor disconnected and running Pickle's map.

 

[RossKean]

I bought my used 2007 this past spring and it came with Leo Vince pipes, K&N filter and a PC III. It has a "custom" dyno tune although I can't say whether it was optimized for power or smoothness. I was (am) disappointed with mileage; getting ~37 mpg. I tried reconnecting the O2 sensor and didn't really see any difference in performance or mileage. Strangely enough, mileage is just about the same whether I am riding at 50 mph or 70 mph - it does go down a bit over 75. Riding in the mountains (British Columbia, Washington etc.) last year gave me the best mileage I have ever seen on this bike.

Is there any reasonably easy way to determine whether the oxygen sensor is actually working? Despite a riding season close to 25,000 miles, I never managed to find the time to actually play with the PC III. Next year I plan to try some different mapping to see if I can improve mileage a bit - don't care whether I lose a bit of performance. I need to make sure the sensor is working as it should before digging into anything.

Ross

 

[olsonm3915]

Is there any reasonably easy way to determine whether the oxygen sensor is actually working? Despite a riding season close to 25,000 miles, I never managed to find the time to actually play with the PC III. Next year I plan to try some different mapping to see if I can improve mileage a bit - don't care whether I lose a bit of performance. I need to make sure the sensor is working as it should before digging into anything.

If you can figure out how to monitor the voltage on the O2 sensor without puncturing the insulation on the wires, the voltage across the O2 sensor should cycle between high and low a few times a second when the system is in closed loop mode. You need to use a quality high impedance voltmeter to avoid loading the O2 sensor- it has a very high output impedance. The EFI system should be in closed loop mode when the engine is fully warmed up, at constant throttle, at a normal cruising speed.

Since the voltage will be changing more quickly than you can read back a digital readout, it is handy to have a scopemeter or at least one with a bargraph display which simulates an analog meter. An analog meter would be perfect for this except most are not sensitive enough to avoid overloading the O2 sensor's output.

If you do go to the bother of trying this test, take the PC III out of the circuit before doing the test, just to make sure it is not overcompensating to the point that the ECU cannot establish closed loop operation.

 

[JamesK]

I bought my used 2007 this past spring and it came with Leo Vince pipes, K&N filter and a PC III. It has a "custom" dyno tune although I can't say whether it was optimized for power or smoothness. I was (am) disappointed with mileage; getting ~37 mpg. I tried reconnecting the O2 sensor and didn't really see any difference in performance or mileage. Strangely enough, mileage is just about the same whether I am riding at 50 mph or 70 mph - it does go down a bit over 75. Riding in the mountains (British Columbia, Washington etc.) last year gave me the best mileage I have ever seen on this bike.

Is there any reasonably easy way to determine whether the oxygen sensor is actually working? Despite a riding season close to 25,000 miles, I never managed to find the time to actually play with the PC III. Next year I plan to try some different mapping to see if I can improve mileage a bit - don't care whether I lose a bit of performance. I need to make sure the sensor is working as it should before digging into anything.

Ross

Sounds like you bought a very nicely setup bike, why mess with it

 

[RossKean]

Is there any reasonably easy way to determine whether the oxygen sensor is actually working? Despite a riding season close to 25,000 miles, I never managed to find the time to actually play with the PC III. Next year I plan to try some different mapping to see if I can improve mileage a bit - don't care whether I lose a bit of performance. I need to make sure the sensor is working as it should before digging into anything.

If you can figure out how to monitor the voltage on the O2 sensor without puncturing the insulation on the wires, the voltage across the O2 sensor should cycle between high and low a few times a second when the system is in closed loop mode. You need to use a quality high impedance voltmeter to avoid loading the O2 sensor- it has a very high output impedance. The EFI system should be in closed loop mode when the engine is fully warmed up, at constant throttle, at a normal cruising speed.

Since the voltage will be changing more quickly than you can read back a digital readout, it is handy to have a scopemeter or at least one with a bargraph display which simulates an analog meter. An analog meter would be perfect for this except most are not sensitive enough to avoid overloading the O2 sensor's output.

If you do go to the bother of trying this test, take the PC III out of the circuit before doing the test, just to make sure it is not overcompensating to the point that the ECU cannot establish closed loop operation.

I may play with it a bit next spring (if it ever gets here). I will try going back to "stock", just to get a baseline. It may not be easy to verify O2 sensor is functioning properly but will see how the mileage is in stock configuration. I have to make sure the basic system is functioning properly before I start messing with PC maps and other stuff.

Ross

 

[RossKean]

I bought my used 2007 this past spring and it came with Leo Vince pipes, K&N filter and a PC III. It has a "custom" dyno tune although I can't say whether it was optimized for power or smoothness. I was (am) disappointed with mileage; getting ~37 mpg. I tried reconnecting the O2 sensor and didn't really see any difference in performance or mileage. Strangely enough, mileage is just about the same whether I am riding at 50 mph or 70 mph - it does go down a bit over 75. Riding in the mountains (British Columbia, Washington etc.) last year gave me the best mileage I have ever seen on this bike.

Is there any reasonably easy way to determine whether the oxygen sensor is actually working? Despite a riding season close to 25,000 miles, I never managed to find the time to actually play with the PC III. Next year I plan to try some different mapping to see if I can improve mileage a bit - don't care whether I lose a bit of performance. I need to make sure the sensor is working as it should before digging into anything.

Ross

Sounds like you bought a very nicely setup bike, why mess with it

No question that I got a nice bike!! Most fun I have ever had on two wheels and other than disappointing mileage it has been totally without problems for the past 25,000 miles. Its nice to have the smoothness and power provided by the PC but would forego some of that performance in favor of improved mileage on long trips. Tank range of 180 miles before hitting reserve is less than I would like. Would probably switch back for "local" riding; easy enough to do with a laptop computer. Bike also came with Penske rear shock and upgraded (Hyperpro?) front springs, Pazzo levers, three windshields, wired for heated gear, color-matched Givi topbox and some other bells and whistles. Leo Vince pipes are in need of a repack so I might go back to the stock exhaust until I can find the time to work on them.