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2011 R1200 GS - Engine surging after synchronization - please help!!!

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David McDougall:
Hi,

My bike  (with 74,000 km on it) was working fine prior to doing a synchronization with the GS-911 today.

As part of routine maintenance, I thought I would check the synchronization, so I connected the GS-911 using my laptop and I believe I followed the directions as prompted by the GS-911.  I used two mercury columns from my mercury four column manometer for the balancer.

Before doing the synchronization I calibrated the exhaust flap successfully.

As it turned out, I actually didn't make any adjustments whatsoever to the bike's two throttle body cables as the differential pressures at idle, and at 1400 - 1800 rpm, were within specification, as per the BMW  Repair Manual DVD.

When I finished the calibration procedure, the laptop said the procedure was successful.  But in reality it was not successful, because when I finished the procedure the engine is now steadily surging back and forth between about 1500 to 2000 rpm, so the bike is not idling normally, and it is not driveable.

There were no fault codes before I started and there are no fault codes now.  An Auto Scan is attached (captured after the synchronization procedure).

When I attempted the synchronization procedure again, the engine runs normally when the idle actuators are locked during the procedure, but when they are unlocked, at the start of the procedure, and at the end of the procedure,  the engine surging starts.

After the problem arose, I did some other things with the GS_911, and the GS-911 says that it successfully performed the idle actuation calibration, as well as the idle actuator test 1 and test 2, as well as the electric fuel pump test, as well as the injector 1 and injector 2 tests.

During the synchronization procedure, I ran the bike at idle, and I also sped the engine up a bit with the twist grip to check the pressure differential between 1400 to 1800 rpm, as per the BMW Repair DVD...would my moving of the twist grip have screwed something up?  Is there a way of "re-calibrating the twist grip?

I have started the engine several times since, thinking it might "reset" itself, but the problem is still there.

Can anybody please help me out?

Thank you.

Dave McDougall
2011 R1200GS

Jughead:
Hi Dave

A few things to remember when doing the synchronization.

There is no sync adjustment for the 1200 at idle.  This is done automatically by the system monitoring various sensors like the O2 sensors on the exhaust, knock sensors, idle actuators,cylinder head temp etc,etc.  DO not ever attempt to adjust the butterfly stop screw on the throttle body.  These have been set in an airflow meter and locked, the 2 on your bike being a matched pair.

Trying to get a motor to idle correctly without first making sure everything mechanical is 100% is a waste of time.  Mechanical things like spark plug condition, valve clearances, gunk in the idle actuators etc all play a part in creating a rough idle.

Have you done the valve clearances?  In doing so, remember that TDC on cylinder 1 is NOT TDC on cylinder 2.  I have had a number of bikes coming into my shop not wanting to idle after the owners tried to do valve clearances themselves and forgot to turn the motor 360deg to get to TDC on cylinder 2.  While you are about it, just do the rocker shaft end float as well.  The motor runs much quieter.

Remove and clean the idle actuators.

Make sure that both lambda (O2) sensors are functioning correctly.  This can easily be seen by plotting the realtime values while the motor is running.  The graph should look something like this:


If one of the sensors is flat-lining it will create a rough idle.

Also make sure the temperatures of the two cylinder heads are within a degree or so of each other, or better yet, the same.

Make sure that there is about 1 - 1.5mm slack on the cables where the adjusters are located on the throttle bodies.  Once you are certain that there is slack, then proceed with the synchronization, following the prompts on the screen as you go along.  Only adjust the cable on the RH throttle body, the side closest to the throttle.  I normally do the adjustment within the normal riding rev range, at around 3-4k rpm. (With a huge fan cooling the motor)

Do not turn the motor off until the calibration screen instructs you to do so.

I normally find that the motor battles to idle once I have completed the sync, but once the GS911 releases the idle actuators, the idle immediately settles.

Turn the ignition off for at least 10 seconds after being instructed to do so.  This allows the new idle actuator positions etc to be written away to the ecu.

Hope this all makes sense and helps.

Regards
Guy

PS.  You may also benefit from downloading the latest version of the software.  I see you are still running  1303.3

David McDougall:
Hi Guy,

Thanks for responding.  I also posted my situation on the BMWMOA Forum and a couple of guys made a suggestion that fixed the problem perfectly.  What they said was to re-set the adaptations using the GS-911 and of course, re-learn the gear positions.  I did this, and the problem disappeared completely and immediately.  Don't ask me why it fixed the problem...because I don't enough about the bike's computers to know why.  But it fixed it.  One of the lads said a friend of his in Denver had the same problem about a week ago in Denver on a 2013 GS, and after much going around, re-set the adaptations and his problem was solved instantly too.  Maybe the good folk at Hexcode can understand the whys and the wherefores of why it worked since they probably understand the underlying computer designs on the expert level.  I would recommend though, that they maybe add a note to the synchronization screen on the next edition of their software to give folks a heads up on this possibility and to try re-setting the adaptations if they do encounter it.

Thanks again,

Best regards,

Dave McDougall

 :)

StephanT:
hi David,

this is a known issue on SOME of the TwinCams... see here:
 http://www.hexcode.co.za/products/gs-911/known-issues

best,
Stephan

StephanT:
Pls do me a favour and send us your AutoScan - we're gathering info to try and isolate exactly which TwinCams exhibit this behaviour...

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