Big trouble with Oxygen sensor 1

macmanCZ

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Hi, my English is not perfect, so I prefer to use an automatic translator.

I have a 2012 R1200GS motorcycle with DOHC engine... The bike rides well, but has a higher consumption when riding quietly... I found out by diagnostics that the bike reports a fault in the O2 sensor on the right side...

I swapped the two sensors between them and the fault is the same... On the graphs I could see how the second cylinder cycles between rich mixture and lean, while the first cylinder cycles irregularly... After warming up it eventually stops cycling altogether and shows the same voltage.

After synchronizing the cylinders, it no longer cycles at all, only randomly appears to change...

I found a wiring diagram on this site and checked the cables from the ECM to the probe. It's fine.

I swapped both injectors, the 1st cylinder still doesn't cycle, the second has strange readings..

I really don't know how to proceed... I understand the engines, the electrics too, I have the diagnostics.. but I'm still stumped..

Before injectors swap, cold engine, idle RPM: https://photos.app.goo.gl/ofuhPZH398z1hKUA8
Warm, idle RPM: https://photos.app.goo.gl/Ussow5mvhXrriVpC8

Final values after injectors swap with increased rpm: https://photos.app.goo.gl/DSBwst5Exv3cSQ3B7
Idle rpm: https://photos.app.goo.gl/BV1GDFbFj1DvZGEh6

Macman
 
we had one a while back... everyone thought it was wiring between a functioning CAT sensor and the ECU - but in the end the fault was inside his ECU.

there are video's on youtube of people opening them up and finding corrosion or pins to resolder and getting rid of strange bugs

you can of course just disconnect both CAT sensors and ride the bike - in fact, it may ride better (depends how muddled your adaptions have become / and or if you regularly have massive altitude change etc.)
and if you buy 2 x 61137702398 you can leave it looking like its all BMW and connected and waterproof but they are NOT connected - they are 1 dollar each
 
In less than a month I'm going on a trip through Romania to Albania. We expect to drive 5000km. I'm afraid to ride a bike that's not 100%...

I've read the whole thread... I'm looking for other options... ECU is the last option.

Is there a normal 4V difference on the knock sensor voltage? 25V vs 21V???
 
I think the problem lies elsewhere... I noticed that the left cylinder is warmer than the right... I have an IR thermometer and the exhaust temperature is 250 degrees on the left cylinder and 60 degrees on the right...
 
not sure I have followed the point you originally made.... as what I took from your first was entirely an electrical issue

why not start with a good old fashioned cylinder compression test and understand if the mechanical health is looking good.

vehicle mileage and service history is also helpful, one pot usually drops a valve around the 90 to 100k mile mark
 
All this time I'm convinced I'm solving an electrical problem... It didn't occur to me that the problem with the Lambda probe wouldn't be the cause, but the effect.

During testing, I noticed that the right cylinder was cold.

I have a compression tester, both cylinders have the same 15Atm. I switched all 4 coils and still the right cylinder cold..

I'll swap the idle valves tomorrow, but I had them out and they both move the same.
 
I don't know the service history, the bike is imported from the UK.. I've had it a year and I've already done the clutch, broken alternator, tps sensor.

It currently has 140,000km.
 
Today I continue testing.. Swapped all 4 plugs, swapped idle valves. no change.

Before I synchronized the throttles, the lambda on the right cylinder had strange readings, after synchronization only a straight line..

I loosened the cable on the right cylinder, the readings on the vacuum gauges are out of tolerance, but the cylinder runs better..

Left cylinder 200 degrees, right 130 degrees...

There must be a problem with the air at idle.
 
I think temperature issues will lead you up another path - you jumped in straight in to complex solutions

is it actually running on BOTH cylinders?
re throttle's check both fully open and close
did you check valve clearances
whilst the plugs are out, did they all look OK (the same...)
did you do a hot and cold cylinder compression test... 15Atm ? (atmospheres?) 220psi ???
plugs out both sides, good battery, 6 to 10 seconds cranking, anything under 150psi would be miserable hot or cold - but its the balance that the most critical
 
I'm coming to believe the problem is the left throttle. I loosen both cables, the engine idles on both cylinders, but the left one does most of the pulling..

at idle, the vacuum of one cylinder is -0.3Atm and the other is -0.5Atm.

If I disconnect the left injector, the idle goes to the right cylinder steadily and the exhaust temperature is higher... I plug both, the left cylinder does most of the work...

When I have both throttles off, the right one is tighter than the left one... the left one has a squeeze groove from the throttle.

Valve clearances checked, plugs look the same, yes 220PSI with cold engine and the readings are just the same on both cylinders.
 
Is it possible that someone has adjusted the throttle stop screws controlling the stop on the throttle butterfly's. These are factory set and should not be touched.
I have seen it where someone has adjusted these instead of the throttle cables to balance the throttle bodies. A very bad move.
 
Yes, it looks like that... Through the diagnostics, I put a lock on the idle valves and set the stop screw on the left body so that both cylinders have the same vacuum..
Now the bike has the right sound at idle, and the same exhaust temperature..

When the heat stops, I'll try synchronizing and see..
 
yes also read world ends if they tamper with throttle stops - don't believe it

what's there to go wrong ? not much (maybe idle stepper motor complains - or not and or needs resetting and or can't... but I think its rubbish).

You could pop off the air intake and or the actual whole throttle body and clean the crud and visibly check the position. I just bought two spares and the clearance isn't identical its close (but so poorly manufactured, vac set up at idle during throttle body build probably the right starting point (but would they really ? NOPE). The drilling for idle air looks like it was done with a blunt bradle !

So check them out and if its looking truly wrong set up the same - I didn't measure but 1.5 thou feeler is about what I saw - I forget but there used to be a base set up on Jags (might have been 2 thou of a good old fashioned inch not this metric rubbish) if its WAY OUT for idle it'll run like a dog and whilst throttle body balance comes after valve clearances and at operating temps, with throttle cables just lifting off idle I wouldn't be happy if when closed it was a disaster...

the idea is to ride safely and enjoy it not wobble like a fool and get taken out by other road users.. coz BMW like selling spares
 
The problem is that the idle actuators do not operate individually and there is no feed back or result circuit, this is why they need resetting.
The idle actuators do not no where they are , just relying on input info from TPS, rpm, etc.
It would have been nice if BMW had included a couple of MAP sensors and controlled the idle actuators individually.
We have to make the best out of what we are given.:)
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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