• Welcome, Guest! We hope you enjoy the excellent technical knowledge, event information and discussions that the BMW MOA forum provides. Some forum content will be hidden from you if you remain logged out. If you want to view all content, please click the 'Log in' button above and enter your BMW MOA username and password.

    If you are not an MOA member, why not take the time to join the club, so you can enjoy posting on the forum, the BMW Owners News magazine, and all of the discounts and benefits the BMW MOA offers?

04 1150rt twin spark - No signal from Motronic to Stick Coil Right Side

T

tweedd23

Guest
All,
I have been working to solve a stuttering problem for some time and have isolated it to no spark signal from Motronic (ecu) to right side stick coil. Both stick coils are good, and spark well on the left primary side. The bike does run ok until you crank throttle down 2k-5krpm and you experience a hesitation at high rpm. I have closely inspected the stick coil connector and all 3 leads at connector (black tracer/green-ecu signal lead, green tracer/black-12VDC lead from ignition and brown-ground to cylinder head (re-installed to ensure ground). With gas tank removed traced ecu lead all the way to ecu plug, and performed continuity check on female plug to ecu (pin 32) also with male side (pin 32) of ecu. I did notice pin 32 and 33 on ecu show as a short on continuity test (0.002), this leads me to believe the ecu sending same signal to both stick coils at same time. After looking at used ECUs on ebay $145-$500 I decided to connect (splice) the right side stick coil lead (the one not receiving ecu signal) to left side. And now both stick coils are firing. Afterwards I did perform another TBS (still dosen't idle at 1150 with 1.5 BBS turns-only around 900) but it does run smoother and almost no hesitation during my short test ride. Does anyone out there know if this is a problem? I plan to ride to work all next week so I guess time will tell. Worst thing I could do is fry Motronic and then I will be back looking on ebay (same as yesterday).

By the way, I just went through an ABSmodulator replacement (found one one ebay). I do still have my original unit (servos seemed to stay on all the time) servo pumps are good, but I do not have a tool to remove the control module. Has anyone canniballized an ABS and replaced a contol module?

Any help on the Motronic (ECU) question would be greatly appreciated.

2004 1150RT 29K Miles.
 
Looking at the schematic, 1150RT Electrical, Z1 and Z2 are the drivers for the stick coils, Z3 for the secondary coil. Since they are on separate pins, I would bet they have separate drivers on the Motronic. As a result you now how a driver designed for one coil, driving two coils. Functionally it should work since they are fired at the same time. However, reliability might be an issue as you suspect.
 
decided to buy another motronic ma2.4 1150rt

Well, its been about 4 weeks now and overall runs good. Actually, around 4K Rpm really smooth, but whenever you demand quick acceleration (4k-6krpm passing in left hand lane) still sense a slight hesitation. If it was a faulty HES I don't believe the bike would run as well as it does. Also, I am only getting 40 mpg (drop from 45mpg). I found a motronic ma2.4 (ebay) from a 2004 1150RS with same mileage as mine approx 28K. Also, the motronic is the exact same part # 7 684 428. It will be shipped Tuesday and I will install shortly thereafter. I am curious if everything will be back to norm 1150 rpm idle (with BBS 1.5), RHS primary stick coil firing from its own driver, and 45 mpg over the same commute route (past 4 years). Additionally, I find myself spending lots of time researching Motronic failures, O2/HES issues, etc. So, I am going ahead and bite the bullet on a GS-911 so I can finally get everything back in perfect condition.

04 1150RT
Jim
 
You'll enjoy having a GS-911. It has lots of logging capability and gives good insight to the Motronic's operation. It can be addictive. Sent on a pm on your old Motronic.
 
All Back to Normal

I installed the motronic acquired from ebay (as stated above) and everything is back to normal. I am now back to 46mpg (normal commute 5th gear ~50mph) and idle is back at 1050rpm after TBS and BBS 1.5. I am not ready to let the original motronic go just yet. I plan to disassemble and attempt to determine why pin 33 driver provided no signal. Also, based on the way the bike ran when splicing pin 32 & 33 driver leads, there must be some slight timing differences between signals from drivers 33 and 32? That's all for now, eventually I will acquire a GS-911 but in no hurry with Christmas looming and must purchase other things at this time. Thanks for your advice and will let you know if I find anything or ready to let the ECU go.
 
Back
Top