Thirsty GSA

[bigmadstu]

Had this 2011 GSA for a few weeks now and it sure likes to drink petrol.
The last 3 fill ups have been at 220 ( ish ) miles and it's taken 31-32 liters. That's 32mpg

Only mod to bike is the exhaust flappy valve has been removed. Bike seems to run ok, idles smoothly and has plenty of go. I've looked at the air filter which is probably original ( 18000 miles ), little bit grubby but I've seen worse, blew it through with the air line and very little came out. Checked the plugs which offered a clue as the throttle side ones were black and sooty, the clutch side ones had brown deposits so look ok. I swapped them over and after a tank of fuel the throttle side ones have turned black and sooty. Clearly this pot is getting an excess of fuel.

I have a GS911 so I've did the idle calibration and engine sync, they were a little out but not much. The only fault code stored was the missing exhaust flap. I also reset and re-registered the adaptation values, very little change. Another tank of fuel confirmed 32mpg and black sooty plugs on the throttle side.

I had a look at the real time values on the GS911 and noticed that the lambda sensors are reading markedly different values, the throttle side pot much higher. Also the fuel trim for the throttle side is 3046% while the other is 0.6%. Bit of a difference there. After swapping the lambda sensors over both fuel trim values are now in the mid 3040's. I'm thinking bad lambda sensor and the throttle side pot has retained the old trim value.

All thoughts and opinions will be appreciated.

 

[diplomaticdanny]

No idea technically what's wrong but I used to get 50mpg out my Hexhead as an average and I'm not particularly slow!

 

[bigmadstu]

Aye, 50mpg was what I was expecting from this bike. It's 35 miles to my work along a busy A road and I'm pretty smooth and cruise at a legal ( ish ) speed while zipping past the odd convoy stuck behind a commercial. ( 40mph limit for HGV's on an A road in the backward part of the UK. ) It's a bit frustrating as I only swapped to the GSA so I wouldn't need to stop for petrol as often, lol

 

[Zx9man]

Do you regularly ride the bike hard it 30in first 60 in second ect

 

[bigmadstu]

I short shift on the GS tbh, usually around 4k

 

[Zx9man]

Bugger unless you are running rich then I have no other idea for me even running at 85 I still ave 49.5 so I am lost for ideas unless you Carrie 500kg on the back ???

 

[Deleted account 190920001]

You can disconnect the sensors. After that reset the adaptations and see how it goes. You either have a bad sensor or a leaking injector. Sensor would be my first though.

 

[bigmadstu]

Thanks for the feedback, it does look like a bad sensor. I'll unplug them, reset the adaptations and "see how it goes".

 

[roamer]

The fuel trim is likely to indicate the system adding fuel, it thinks it's running lean,
its possible the lambda sensor is faulty
generally an intake air leak is the cause,
Can you see the raw voltages of the sensors, ideally erase the fault and swap them over and check again,if the fault moves it confirms a bad o2 sensor,
As you say it's powerful and no starting trouble , a leaking injector is unlikely
Roamer

 

[bigmadstu]

Thanks roamer, forgot to mention that I've sprayed all the intake connections looking for a leak. Found nothing. I did swap the lambda sensors and the bike immediately trimmed the other pot to a high value. The raw voltages of the sensors are significantly different. I've seen similar before though and the odd lambda readings were caused by another issue. ( Failing coil previously which I doubt I have since the bike is smooth and powerful. )

 

[roamer]

You seem to be on the case with this, my gsa was 50 mpg,
The fuelling won't be significantly affected under acelleration only cruise and idle,
Your journey and riding description fits with the diagnosis,
If the oil is a bit dark it may be worth changing it as a precaution, as it is unknown how long it's been running rich,
Interesting you mention the misfires previously on another bike,
it's the unburnt mixture causing high oxygen in the exhaust with similar high fuel trim , but with a loss of power,
Let us know the final result bud,
Roamer

 

[Ted]

Try running some injector cleaner, RedX or similar with next fill up, then take for a good run. Not unknown for a sticking or dirty injector to give similar problems. Always try cheapest options first

 

[bigmadstu]

Thanks again for all the feedback guys. I unplugged the lambda's, reset the adaptations and took it for a 50 mile run today. Bike felt smoother than it's ever been and I noticed an absence of popping from the exhaust. Pulled the plugs on both sides when I returned home and they are a nice brown colour. I will run some injector cleaner through it this week but all looks well so far. I'll not know the mpg till later in the week as I'm grounded babysitting tomorrow and back to work on Tuesday.

Hoping to get 50mpg as I do 70 miles per day and the whole idea of the GSA was that I wouldn't need to stop for petrol as often. I'll update this thread when I know.

 

[Deleted account 190920001]

Sounds like it is an O2 sensor then. I suppose if mpg is your ultimate goal then you better replace the duff one. Give it a test and see, you might be happy with what you get and leave it alone.

 

[Greenman14]

Is injector cleaner ok for a Cat?

 

[bigmadstu]

Is injector cleaner ok for a Cat?

I think that's the least of the cat's problems, I suspect it will currently look like an unswept chimney, lol

 

[Deleted account 190920001]

I think that's the least of the cat's problems, I suspect it will currently look like an unswept chimney, lol

Possibly, if it has been over fueling badly enough the cat will be knackered. Que a monty python dead cat scene ;-)

 

[bigmadstu]

Possibly, if it has been over fueling badly enough the cat will be knackered. Que a monty python dead cat scene ;-)

Sounds like a good excuse to treat it to a set of decat headers.

 

[Bendy toy]

A failing coil will cause the the ECU to run the mixture weak.

Normal sparks burn all of the fuel so Lambda values adjust to the ECU map settings.

Failing plug(s) or failing coil(s) will cause some fuel to go down the pipe unburnt. The unused oxygen will affect Lambda values causing ECU to inject additional fuel.
Result is rich running.

Fix the faulty plugs or coils and its likely to sort itself out.

GS-911 cannot directly diagnose a faulty coil. It has to be done by diagnosing the problem from the readings you can get.

How do I know? I had the same problems with a failing coil coils making me believe a lambda had failed.

 

[bigmadstu]

A failing coil will cause the the ECU to run the mixture weak.

Normal sparks burn all of the fuel so Lambda values adjust to the ECU map settings.

Failing plug(s) or failing coil(s) will cause some fuel to go down the pipe unburnt. The unused oxygen will affect Lambda values causing ECU to inject additional fuel.
Result is rich running.

Fix the faulty plugs or coils and its likely to sort itself out.

GS-911 cannot directly diagnose a faulty coil. It has to be done by diagnosing the problem from the readings you can get.

How do I know? I had the same problems with a failing coil coils making me believe a lambda had failed.

Yes, in my experience also, odd lambda readings are usually a symptom rather than a cause. I think in this case though I do have a faulty lambda as swapping them over moved the issue to the other cylinder. I've done about 50 miles now since I unplugged the lambdas and reset the adaptations. The bike has gotten smoother with no exhaust popping on overrun and the plugs are no longer sooty.