GS12 only firing on one cylinder

Demongroover

Well-known member
UKGSer Subscriber
Joined
Jan 23, 2006
Messages
577
Reaction score
3
Location
Derby
My '04 GS12 was fine last time I took it out, it has been stood over xmas on the optimate and when I fired it up to go for a ride it would only fire on one cylinder. Under load it sporadically goes back to two but is eratic.
It feels electrical but at this point I'm just guessing.
I recently serviced it (I have always serviced my bikes for many years), and replaced all 4 plugs, air and oil filters, alternator belt etc etc.

Before I start tearing it apart are there any known common causes?
 
Mine did the same once when stood for a long while, I shut it down and did a TPS reset and all was well when restarted. I think the ECU running the engine forgot itself and the TPS reset gave it an electronic nudge in the right direction.

I'd try the TPS reset first because its free.

You might well find you have a faulty stick coil, both my lower ones were split due to internal rusting. Could also be moisture around the spark plugs.
 
Sounds simular to the way my 1150 was runnig a week or so ago. Turned out to be a faulty injector. Don't know if the 1200 are he same though.
 
its not...

a dislodged throttle cable on one of the injectors by chance.

i know its a comon problem on the R1150GS.
 
I don't think the 1200 have that problem. Aren't their throttle electronic. Could be wrong. As I said only learning about my 1150 never mind the newer 1200.
 
i would swop parts over left to right to see if i can move the fault over if everything else looks ok.
Have had a bad plug before just because it's new don't rule it out
 
Had this problem

Can almost 100% guarantee you it is the small coil connection very close to the spark plug connector under the main black plastic spark plug cover, if one isn't quite clicked on properly you lose that cylinder, this is what happened to me, after I had driven 50Kms! unfortuanately I had to drive back that 50Kms to BMW to get it fixed and then so on!
 
Pukmeister said:
Mine did the same once when stood for a long while, I shut it down and did a TPS reset and all was well when restarted. I think the ECU running the engine forgot itself and the TPS reset gave it an electronic nudge in the right direction.

I'd try the TPS reset first because its free.

You might well find you have a faulty stick coil, both my lower ones were split due to internal rusting. Could also be moisture around the spark plugs.
Click to expand...



Sounds good, I take it TPS is Throttle Position Sensor, but how do I reset it with the ECU? :nenau

Thanks guys for all the ideas, all sounds pretty likely, I meant to go and have a fiddle in the garage today but been too busy.

Any thing else I should check?
 
TPS reset routine:

1) Disconnect battery for about 30 seconds then reconnect (causes ECU to lose it's memory of Throttle Position Sensor).
2) Turn ignition to on but DO NOT start the engine.
3) Slowly wind the throttle fully open to fully shut, repeat this three times.
4) Turn off ignition. (ECU now stores TPS position data in memory).
5) Wait 5 seconds.
6) Turn on ignition again and start bike.

Before doing this, I would check that the wiring to the TPS itself hasn't been kicked or disturbed, its the electrical unit on the air intake in front of your Left foot.
 
Right, finally managed to get a look at the BMW.

Tried the TPS reset to no avail, still the same.

Started up, right cylinder cold, left cylinder hot.
White spark on right cylinder, so decided to swap coils over from left to right.
Found left lower coil plug and the socket snapped on left coil itself!
Parts now on order but confused as to why left cylinder would be the one firing when that's where I found a definite fault? :nenau
Or do I have two problems?

Collecting parts today, will update when fitted. :confused:
 
The HT leads break down, specifically the insulator causing it to ground to cylinder head. Common fault on the 1150 and time wise the 1200 is due it as well.
 
Snoopy said:
The HT leads break down, specifically the insulator causing it to ground to cylinder head. Common fault on the 1150 and time wise the 1200 is due it as well.
Click to expand...

What HT leads on the 1200 snoopy?

There aren't any they are both Stick coils

Demongroover :- BVe very careful with the little plastic locking tab on the coil connector but remove the connector THEN remove the stick coil look at them and check for obvious corrosion if there is a lot order the appropriate coil

Take the plugs out and if they are really black and yeugh stick new plugs in
 
Demongroover said:
My '04 GS12 was fine last time I took it out, it has been stood over xmas on the optimate and when I fired it up to go for a ride it would only fire on one cylinder. Under load it sporadically goes back to two but is eratic.
It feels electrical but at this point I'm just guessing.
I recently serviced it (I have always serviced my bikes for many years), and replaced all 4 plugs, air and oil filters, alternator belt etc etc.

Before I start tearing it apart are there any known common causes?
Click to expand...

Definatly check your getting a good spark at the plug, the stick coils are prone to failing, replaced 3 (2 main, 1 secondary coil) on my '04 so far! (63K miles)
 
Jonnie Boy said:
Definatly check your getting a good spark at the plug, the stick coils are prone to failing, replaced 3 (2 main, 1 secondary coil) on my '04 so far! (63K miles)
Click to expand...

Will do, parts not arrived, coming Thursday.
The plug that connects the left secondary coil has snapped, must've been hit by something. Replacement repair kit (plug and the three wires is £15 + VAT).
I ordered the coil as the sleeve where the plug goes in is missing (snapped off).

Also, ordered the gear indicator device for the back of the gearbox. I've tried drying it out and sealing it with grease but it's gone faulty again :(
 
Jaythro said:
What HT leads on the 1200 snoopy?

There aren't any they are both Stick coils

Demongroover :- BVe very careful with the little plastic locking tab on the coil connector but remove the connector THEN remove the stick coil look at them and check for obvious corrosion if there is a lot order the appropriate coil

Take the plugs out and if they are really black and yeugh stick new plugs in
Click to expand...

Apologies my error, I was referring to the 1150 (they went on mine). Ignore me. :thumb2
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
You must log in or register to reply here.

Similar threads

1150 gsa only firing on one cylinder after fuel drain down.
Replies
5
Views
219
Paul Young
Paul Young
ferguscawley
A puzzler - 08 GSA on one cylinder only
Replies
12
Views
1,105
EVskiy
EVskiy
Howard J
Removed tank...now running on one cylinder
2
Replies
20
Views
4,136
Howard J
Howard J
mspenz
Running rich but only on one cylinder.
2 3
Replies
46
Views
17,013
Mzokk
Mzokk
GS1100 1998 running on one cylinder
Replies
10
Views
3,186
theoneandonly
theoneandonly


Back
Top Bottom