Losing power

[west coast traveller]

On my way to the Dragon rally today. 1150 gs twin spark. All seemed fine at up to 3500 revs but started losing power at around 4000 revs in 6th gear under load.Needing to drop a couple of gears to maintain 70mph on gradient. Motor feels like it is missing and not pulling. I changed stick coils with a spare but no difference. Throttle Cables are seated. I changed main plugs for new in case plug was breaking down but no different. Old plugs had light brown electrodes so ok. Bike feels fine when travelling at 30-50mph and revs freely in neutral-no popping or backfiring. I took the bike out for a good run a couple of weeks ago and all was well and not used till today. My gut feeling is a fuelling problem but I would be grateful if anyone has any other ideas I should check out.

 

[kirky1298]

Hall sensor

 

[west coast traveller]

Hall sensor

Possible, but HES replaced not too many miles ago....did cross my mind though
Thanks for the reply.

 

[Ian J Hartley]

Long shot, but you haven't got a wet air filter which might be freezing up.

 

[west coast traveller]

Long shot, but you haven't got a wet air filter which might be freezing up.

Thanks. I'll check this out tomorrow.Bikes garaged to tonight so should be able to confirm or otherwise.

 

[davegs]

Gutless

How long since you changed the fuel filter? have you checked fuel tank breather is not blocked?, try running with the fuel cap undone see if it has an effect if ok obviously breather probs. Or could be crap Welsh petrol!!.

 

[west coast traveller]

How long since you changed the fuel filter? have you checked fuel tank breather is not blocked?, try running with the fuel cap undone see if it has an effect if ok obviously breather probs. Or could be crap Welsh petrol!!.

All boxes ticked-spent 5 hours yesterday checking above and valves, injectors, plugs and fuel pump. There seems to be a definate misfire but can't islolate to a particular cylinder. Can't blame Welsh petrol as still in Manchester area!

 

[ghiribizzo]

Can I ask how you checked the injectors?

 

[The Grey One]

You said you replaced stick coils with a spare, was that just one?
My 1150 (also twin spark) did exactly the same thing at the end of summer 2011. Needed both stick coils replaced before it ran properly again.


John

 

[davegs]

You said you replaced stick coils with a spare, was that just one?
My 1150 (also twin spark) did exactly the same thing at the end of summer 2011. Needed both stick coils replaced before it ran properly again.


John

How did you know the spare coil was good?

 

[west coast traveller]

update......

Sorry for delay in getting back to your replies.
Managed to get to Dragon rally in back of a van and rode last 10 miles. (don't think this counts as cheating as I'd already ridden 430 miles to get to Manchester).
Any road up, by the time I got back to the van to get back to Manc, bike running on one cylinder only (offside). Nearside flooded but both primary and secondary plugs giving a good spark when dried. Bike then runs rough and goes back to firing on one. Garaged over Sunday night and AA called. Relayed back to Ullapool yesterday thanks to Colin,Tam and Hughie who drove the 3 legs of the journey.
I had changed coils with a known good one. Now I know which cylinder is misfiring I swapped coils again and no improvement. From memory, the bike should still run on the secondary plug.
Next step compression test?

 

[west coast traveller]

Since last post I have been steadily working through testing systems.
1. Checked Hall sensors with testing rig (led and 12v battery) all seems well. Timing spot on.
2. Replaced lambda sensor and reset motronic .
3. Resistance check on injectors -16ohms so ok
4.Purchased new stick coil so now has 2 virtually new coils. But sparks seem weak.
5. Checked TPS. This was rather interesting as it registered 0.7v. I adjusted it to 0.36
and gave it run. OK for first 100 yards then lost power and needed to slip clutch to keep engine running in gear. Checked TPS again and showing 0.1v. Reset and now constant 0.36 v with throttle closed.
6. Throttle bodies balenced.

Currently bike will start when cold but runs rough. When warmed up to ticks over smoothly but only revs to 6-7000 revs before cutting out. It will set of from standing in gear no problem then loses power at around 4000 revs. with misfire and backfire evident.

Not really sure what to check next other than go back to fuel system.
Does any one know whether it is possible to check voltage at input to the stick coils in view of poor spark? I'm beginning g to wonder whether ecu is faulty. Maybe a visit to the not so local BMW dealer required.......


Sent from my MID using Tapatalk 2

 

[Ian J Hartley]

You might want to revisit your TPS. It's a variable resister and could be giving the wrong voltage value higher up. Leading your motronic to think that the throttle is not as far open as it is in reality.

When you do a voltage set up measure the voltage over the complete range. You should get a smooth linear voltage change with no jumps. Mine goes from 0.36v to 4.69v.

 

[west coast traveller]

You might want to revisit your TPS. It's a variable resister and could be giving the wrong voltage value higher up. Leading your motronic to think that the throttle is not as far open as it is in reality.

When you do a voltage set up measure the voltage over the complete range. You should get a smooth linear voltage change with no jumps. Mine goes from 0.36v to 4.69v.

I'll have a closer look. I had definatly set it up correctly at 0.36v so seems strange that it should then give a low reading of 0.1ish after being ridden for a couple of hundred yards. Thanks for the reply.

Sent from my B92 using Tapatalk 2

 

[Ian J Hartley]

TPS nominal values

These values are taken from my bike 2003 R1150GS twin spark, to give you an idea.

Disconnect the electrical plug at the TPS and measure the TPS Resistances.
As you look at it from the left side of your bike pin 1 is on the left and pin 4 on the right.*

Pins 2 to 4
Fixed resistance should be close to 741 ohms

Pins 3 to 4
with throttle closed = 928 ohms
with throttle open = 1837ohms

Pins 1 to 4
with throttle closed = 1119 ohms
with throttle open = 1632 ohms

Pins 2 to 3
with throttle closed =1685 ohms
with throttle open = 1320 ohms

Pins 1 to 2
with throttle closed = 1693 ohms
with throttle open = 933 ohms

Your values should be relatively close to these. Assuming my bike is OK.

The motronic also uses the position voltage from pin 3 so it might be worth checking that this voltage is also smooth and linear from throttle closed to throttle open. Also measure the reference voltage at pin 2. This should be 5v.

 

[Ian J Hartley]

Slight correction to my last:-

As you look at it the TPS from the left side of your bike pin 4 is on the left and pin 1 on the right.

Sorry about that

 

[west coast traveller]

Slight correction to my last:-

As you look at it the TPS from the left side of your bike pin 4 is on the left and pin 1 on the right.

Sorry about that

Just checked all values (in red) against yours:


Pins 2 to 4
Fixed resistance should be close to 741 ohms 728

Pins 3 to 4
with throttle closed = 928 ohms 844
with throttle open = 1837ohms 1757

Pins 1 to 4
with throttle closed = 1119 ohms 917
with throttle open = 1632 ohms 1543

Pins 2 to 3
with throttle closed =1685 ohms 1575
with throttle open = 1320 ohms 1240

Pins 1 to 2
with throttle closed = 1693 ohms 1537
with throttle open = 933 ohms 858


Voltage at Pin 3 .01>4.13

Voltage ref at Pin 2 4.8 volts


The Pin 4+1 voltage is 0.36 with a smooth progression to 4.65 at half throttle then no further increase when opening from half to full throttle.

I would guess that the resistance values are probably within range and my test meter is more "budget" end so that might also account for some of the discrepancies.

 

[Ian J Hartley]

Mine also only gives TPS voltage to half throttle position.

Ok from those values I would expect the TPS to be OK, and your troubles are else where.

Good hunting

 

[west coast traveller]

Thanks for the help. I think injectors/fuel pressure and spark next on list.

Sent from my B92 using Tapatalk 2

 

[Ian J Hartley]

Does any one know whether it is possible to check voltage at input to the stick coils in view of poor spark? I'm beginning g to wonder whether ecu is faulty.

The low tension voltage at the stick coil are:-

Pin 1 black/green or violet switched negative pulse from motronic.
Pin 3 green 12 v dc from ignition switch.
Pin 2 brown earth.

I doubt it's your motronic.