Hi All,

I am a new member; however, I have been browsing these forums for years to help troubleshoot the many issues my wife's (now mine, she got the new car, go figure) R53. It is an '04 R53 6MT car. NOw has about 208K miles on it.

For the last 2 months or so, after performing a ton of maintenance (single mass clutch, seals, bearings, rod bolts, rings, etc) I experienced a 3-4 second long misfire upon start up about 50% of the time. I attributed it to a semi clogged fuel filter so replaced the filer. The problem did not go away. About a week ago while driving normally I got a sudden, consistent misfire on cyl 2. Upon arriving home, after limping it, i determined the cyl 2 injector was not firing. I got a set of used injectors from Way MW and installed them. Issue persisted and the same injector on cyl 2 did not fire. I then turned my attention to the harness. After inspection all 4 injectors received 12V when Key on engine off and the signal side had good continuity (0.3-0.4Ω) from the injector connector to the ECU associated pin (A20 for cyl 2 injector).

These facts obviously concerned me because it pointed to the fact that the ECU injector driver for cyl 2 may be damaged. This being a BMW designed car, anything electronic is a massive pain. Upon some research I learned the injector driver circuit is contained mostly in one chip. If the chip is at fault, I think I can replace it.

My main questions are:

(1) Any other ideas as to why injector 2 is not firing before I open the ECU case? I have the later "silver clamshell" ecu case with no fasteners.
(2) As far as replacement ECUs, what do y'all recommend? (unlocked/virginized, send in used to be reprogrammed, full EWS/key/ECU set from donor car)

Thank you so much for your help. This forum has been a great resource for me over the years.

 

How are you certain that injector # 2 is not firing? And, have you ruled out a bad coil pack, plug, or plug wire?

 

(2) In my opinion the best way is full EWS/key/ECU ,is not so expensive, around 140-180$.Worst case, must recode ECU for Cruise control, transmission type,aircon and traction control.
Unlocked ECU is also a good way but is little bit more expensive.If you decide for unlocked ECU pm me, I have a spare one.

 

The old screwdriver trick. You place the metal end on the injector body and the resin/wood end on your ear. If the injector is firing, you will hear an audible click.

 

Currently my plan is to get a EWS/Key/ECU matched set from a donor car this weekend. The car is a 2005 R53 6MT with cruise control, A/C, DSC, ABS. My car is a 2004 R53 with the same options. I think this means I will not need to perform further programming.

I do not have the EMS2000, I have the MS5150. So does the donor.

 

Swapped over the ECU, EWS, and key electronics from the donor car. Car started but still misfiring in the same way. It appears that the ECU is not the issue.

Any ideas?

Seems to be a wiring harness issue, I just need to find where. I have not checked the "ground side" from the injector driver in the ECU to GND. Anyone have a pinout or knows if the GND pinds from the injector driver are independent? When I looked at the board it seemed like all grounds went to the gnd base on the board and then to various gnd pins.

 

Check wire Brown Green from Injector 2 to pin 20 of ECU big socket.

 

Thank you AdrianCL. I have checked this connection, along with Injector 1,3,4 connector to the respective ECU pins (21,22,19) and got a reading of 0.1-0.2ohm. Also checked the "red wires". same 0.1-0.2ohm and 12.4V at the connector when key-on-engine-off.

Installed the new ECU, EWS, and BC1. No change. Car fires up and idles about 1200-1400 rpm with a distinct misfire. Checked spark again. Good on all cylinders. Used the screwdriver method to check injectors again after swapping known good cyl #1 injector. No matter which injector is on #2 cylinder, it will not fire. It seems obvious this is an electrical issue. All injectors are 12ohm +/- 0.1 ohm.

I tried to make a simulated injector test light using an LED and 330ohm resistor. I only tried this while cranking. Seems that injectors do not fire continuously while cranking. Will try to watch cyl 2 injector while engine is running with an oscilloscope and the test light tonight.

Could this be a cam or crank sensor issue?? Odd that only one injector would be commanded off. I am honestly at a loss. Any help appreciated.

Ryan

 

you did a compression test?

 

No I have not, but a boroscope has verified engine is mechanically intact. Plan is to compression test all cylinders tonight.

Even if cam was wiped, piston had a hole in it, or valves not sealing (very unlikely, motor refreshed recently) it would not explain the fact that the cylinder #2 injector is not firing.

 

Anyway, just for test try this on injectors 2.

 

Adriancl,

The fuel injectors are not clogged. I have tried 3 different injectors on cylinder #2. One set has been cleaned ultrasonically in solvent.

 

Compression test on cylinder 2?

 

Compression Test results:

#1: 128 psi
#2: 140 psi
#3: 155psi
#4: 155psi

 

Found the issue. It took getting the oscilloscope out. I did get an injector pulse on cylinder #2 upon initial start up of the engine. After about 8-10 seconds of the engine idling, an audible difference in the the sound of the engine was detectable and the injector pulse went away.

The ECU (MS5150) will turn off output to an injector if it detects a consistent misfire on that cylinder. Output shutoff occurs once the ECU decides to enter limp mode, which seems to coincide with about 8 seconds of misfire on any particular cylinder.

Upon further investigation I found that the #2 spark plug was bad. There was huge resistance between the electrode and the wire side contact. It appears the plug is internally damaged in some way. I have never seen this issue is a car before. New set of spark plugs fixed the issue.

Will continue to monitor this, but I hope it is all fixed. Anyone have quick recommendations on plug type and gap? I will also browse around the forum for suggestions.

Thank to all that helped. Pic of the injector pulse attached.

 

That's some good information...I'll tuck that one in the old memory bank.