General Category > Engine related issues

Why No Fault/Trouble Codes Set?

(1/2) > >>

AlaGS:
2005 R1200GS 51K mi. Bought new in April 2004. Bike is in perfect tune. New Air filter, plugs, valves just adjusted, Alway fresh fuel and lubricants. Ran like new until this problem. Problem: Cranks and idles fine. Runs fine until throttle is applied past ~30%. At that point engine misses and looses power. Once you back of the throttle back to the ~30% point it picks up and runs fine again. Can wind engine up to 6K+rpm
very smoothly as long as you keep the throttle under the ~30% point. NO Trouble/Fault codes/lights! Checked/replaced the following with no improvement: Fuel pump controller, TPS, and verified fuel pressure at 3.5 bar. After more troubleshooting, it looks like the secondary coil on the #1 cylinder (Right side) is the culprit. Currently waiting on new coil. I am reasonably certain that this will correct the problem but two questions:
1. Why no fault/trouble codes? I would think that with raw fuel being dumped in the cylinder and not being ignited the ECM would receive a rich O2 reading from that sensor or possibly get a knock signal as it backfires. Or why it doesn't register the misfiring. I know cars can…
2. Does anyone know if there is a book or white paper out there somewhere on how the BMW ECM/Can system works and a listing/definition of codes? This troubleshooting in the blind is not the best method. (PS  I have my own GS-911-wifi on the way now…been waiting for an excuse to get one!)

Any help is appreciated

Thanks

AlaGS

marchyman:
1) My guess: because BMW (and you) didn't pay for the design and manufacturing of sensors to measure spark output. A coil is composed of two loops of wire that are magnetically coupled.   Unless you add extra circuitry the bike can only tell of something is wrong with the primary circuit, the loop of wire connected to the bike.  The other loop is only connected to the spark plug.   No circuitry feeds back to engine management.    I'm sure it could be done, but to add sensors every place one would be nice to have would likely make the bike bigger, heavier, and costlier for little gain.

The bike also can't detect bad spark plugs.  A friend had a similar issue to yours.   Changing plugs resolved the issue.   Examining the old plugs with a magnifying glass after cleaning off the grunge found a crack in the porcelain.

2) Dunno.  However, you are not trouble shooting in the blind.  It still comes down to air, fuel, and spark, all at the right times.  Reading real time values can give you some insight as to what might be wrong.   Best to read and capture some real time values when the bike is working correctly so you've got something to compare when things go wrong.

WayneC:
The 05 model is a relatively old model and so the diags/fault codes included in the firmware will be more limited than the newer models

I would have expected some 02 sensor fault though. The problem does suggest a possibility of a throttle position sensor fault as well

AlaGS:
I know it's been a while since I've posted but I been waiting for a resolution by BMW. Since I had a ride coming up, I took it to a BMW dealer to have it repaired. Mistake.
They have had it for three weeks and it's been a disaster; I explained exactly what the symptoms were (original post) and after redoing everything that I had already done they started do silly stuff like changing plugs (it had brand new plugs in it), rebalancing the TBs, replacing TPS (already done). Then they called BMW Support and they wanted them to redo everything both of us had already done! Then they wanted to check the timing gear shaft key to see if it was bent…
(remember, this bike cranks and runs like crazy up to red line as long as you don't get it past the ~30% throttle point). There's more but I will not bore you with the sordid details. Needless to say, I am sorely disappointed in both my shop and BMW support. It seems they forget that this is just an internal combustion, spark ignited engine…  Anyway, I am now convinced that it's the Motronic engine controller. The controller is about $1100 US for a new one so my questions are:
1. Does anyone have any other ideas?
2  Is there a source for rebuilt units?
3. What confidence can one have in a used one or should I just spring for new? (I plan on keeping the bike)
4. What procedures/processes should be followed when replacing the CPU? (TPS calibration, TB sync, other?)

Thanks

AlaGS

schuppi:
it looks like the secondary coil on the #1 cylinder (Right side) is the culprit. Currently waiting on new coil.

Hello AlaGS,
so it is, youre right, misfire will not be detected by motor control unit.
But reading your explanations of engine surging, I think youre on the right way by changing the coil.
Please look for the main coils. It's well known that these coils cracks at the isolation. New ones with better performance are marked with a grey coloured top.

Navigation

[0] Message Index

[#] Next page