Dramatic drop in fuel economy

[Roy Bohnen]

Greetings all.  I had posted this on the GS911 Forum, but have not received any responses.  I am hoping that I can get some guidance here
The trials and tribulations of replacing the transmission has taken me in some new and curious directions.  Bleeding Whizzy Brakes without being able to power up the ABS, on and on.
After getting everything back together, I found that the fuel line connections started to leak, so I replaced them with new fittings from Beemer Boneyard.  (Thanks Jughead from BMWMOA forum)  The engine runs better, but still stutters at full throttle.
I put some Sea Foam into the tank along with some injector cleaner and ran it for a few hundred miles yesterday.  I have had this bike for many years, and have always averaged just under 50 MPG overall.  On a trip yesterday, I dropped to 38 MPG.
Even when I get spirited in the backroads of the Blue Ridge mountains, I seldom get less that 45 MPG.  I do reset the MPG fairly often.
There is no misfiring, stuttering or hesitations at normal speeds and ridings.  However, when I roll the throttle open all the way, the engine stutters.  There is the occasional stutter when cold starting but that always clears up.
Coils could cause this, as could O2 Sensors.  Remapping the Throttle Position Sensors (open and close the throttle 3 times with th engine off) could play into this as well.  Has anyone else experienced this before and have any thoughts on where to start?
I have a GS911 but am not completely familiar with all of the options.  I got it mainly for the Brake Bleeding, only to find out it is not really needed for that.  But it wil help me with this issue.

This is for a 2006 R1200RT with 68,000 miles on it.  Thanks

Update:  Yesterday I did the Remapping of the Throttle Position Sensor by turning on the ignition, then slowly opening and closing the throttle 3 times.  After shutting off the ignition, I started the engine and went for a ride. This improved gas mileage up to 43 MPG, but there is still an issue.  I plan on connecting the GS911 to the bike in the next few days.  Hoping someone can point me in the right direction as to which test or tests should be performed with the GS911 so I can get to the point and resolve this problem.  

Thanks

[Dave McDougall]

Hi,

 

Have you tried re-setting the adaptations?

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[adf]

Partially blocked exhaust system

Partiallly blocked intake

Low intake flow/MAF/intake temp.

fuel pressure

wheel bearing[s]

[seized brake caliper]

Transmission drag

Final drive drag

All of the above can produce this inc fuel consumption effect collectively but I suspect eng management fault [BMSK]

[Kiriakos Belekoukias]

Hi Roy,

As far as it concerns the oxygen sensor, plot "real time values"--> "oxygen sensor" and check if the oxygen sensor (aka lambda) works correctly (min/max values).

It has happened to me that an aged lambda didn't work as expected. GS-911 didn't saw it as malfunction so there was no error logged.

What i mean by "correct" is that the graph should bouncing up and down every second (mine did it every 10 seconds). Have in mind that bike's ECU considers the lambda in the fuel supply equation in closed loop mode. Just show us the plot.

Hope I helped!

Kiriakos

[Xavier Stainier]

HI from Belgium

I have a R1200RT from 2007 with approx 80,000 miles on it and my average MPG is 36, and that for about 30,000 miles (when I bought it).

In my humble Opinion, the less Gas the better, no ?!?

 

X.Stainier

R1200RT ‘07

K1100LT ‘96

R60/5 ‘71

 

De : gs-...@googlegroups.com [mailto:gs-...@googlegroups.com] De la part de Roy Bohnen
Envoyé : jeudi 27 mai 2021 16:31
À : GS-911 Field Diagnostic Tool for BMW motorcycles
Objet : [GS-911] Dramatic drop in fuel economy

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[Phil W2GE]

Have you tried asking on bmw sport touring forums?  There’s a guy on there, dirt rider,  If he can’t figure it out, no one can.

[Gerald Hodatsch]

Hi, 

a friend of mine had a similar problem but much worse. Reason was a small rupture in the fuel hose immediately after the pump IN (!!) the fuel tank. The mech said this is not uncommon for older bikes. I would generally start with checking the fuel pressure, working along the whole fuel supply system. Also check the filter (seeve) directly at the fuel intake in the tank. If there is a rupture, dirt may have been sucked in an can partially clog the pump or the fuel filter, regulator or even injection valves.

Another friend had a bad pressure regulator with similar crazy behavior. But this was on a K1200LT.

Br,

Gerald

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[Anton Venter]

Use your 911 maintenance functions and diagnostics and faultfinding. It is really great and effective. Idlea and stepper valve can be set and calibrated. The cylinder balance adjustments are also dine with the 911. Excellent tool. 

From where are you?

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[Jamie McCallister]

Hi, Since you took it apart to do the gearbox, it’ll be something simple as in something isn’t back together properly. Either there an air leak on the air box side so the engine is pumping in more fuel to compensate or there’s a fuel leak somewhere. J

[adf]

Correct or whatever should be measuring it isn't doing that accurately. Leak doubtful.? You smell it before you measure it. I assume the fuel consumption is being calcualted by  -  uplift in US gals divided into  mileage and not relaying on the consumptiometer? Average trip miles before refuel = 200 imperial. [US gals and imp gals differ]

[Roy Bohnen]

Thanks everyone.  I have taken the tupperware off of the bike several times since to visually verify that all connections - electrical and fuel - are intact.  Brakes / wheel bearings are not dragging, no smell of fuel leaking, which was there prior to replacing the quick connect fuel fittings with new connectors from Beemer Boneyard.  Jughead from the BMW MOA has suggested that I replace the plugs with new, then verify that the upper and lower coils work as expected, then plug in the GS911 to run the  "Engine" > "Service Functions", select "BMSK Adaptions" from the dropdown list on the right.  Below that, select "Reset Adaptations" from the dropdown list, and then click on "Run Function".

I plan on doing this later this week.  I rode it to work again today, averaging 44.5 MPG on country roads.  Way lower than normal for me.  

[Ray Laureano]

What does your spark plugs look like? That should give you some info on your air/fuel mixture. The injector spray pattern could be a factor. You mentioned sputtering at quick WOT which indicates a fuelling problem. Mechanical faults are not picked up by the GS911. 

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