I have not. I don’t know how! I’m knew to this work-on-car stuff. I can learn it though. So far I’ve remained zeroed in on things specific to this misfire-on-one-and-only-one-cylinder situation. Fuel pressure seems like it wouldn’t manifest as just this one cylinder having issues would it? Sent from my iPhone using Tapatalk
I’m not a mechanic but I am curious on how fuel pressure would only affect one cylinder all the time.
It would not effect only one but its a good idea to rule every thing out. Low fuel pressure and a weak injector tighter could cause a it to miss. The main problem with this is its an electric pump so RPM won’t change fuel pressure. It could be that at higher RPM you can’t tell it is missing. It could be a bad fuel regulator causing the problem. But agin it is odd that it is one cylinder. It is more than licked a electrical problem. Don’t rule out bad new parts. When I worked on cars more than once I put on a new part that was bad. here is what I would do. I would pull all 4 plug wires off the plugs, take the number 2 plug out, put it on the plugs wire and hold it on a metal part of the motor and have someone spin it over and look and see if you get spar. Be carful not to touch the plug, you don’t want to get shocked. If you see it sparking you have a fuel problem if no spark it’s electrical back to the basics
This is the plan for tomorrow - fingers crossed that a few more hours of diagnosis and swapping parts around will reveal the problem and solution! Thank you all for the help and advice, Lee especially has been awesome!! Sent from my iPhone using Tapatalk
I'm nearly out of bullets now. Here's what I've done today, but the spoiler alert is that nothing has changed - I still get trouble code 0302 for misfire cylinder 2 after doing the following: checked the codes again to be certain I knew where we were starting. Had two codes: '0302 Misfire Cylinder 2' and '0313 Misfire detected with low fuel' cleared those codes and confirmed they were gone from the computer tested the cylinder 2 spark plug for spark. Pulled all four plug wires, then removed the spark plug from #2, plugged it in to the wire boot, put the plug near a metal screw on the intercooler bracket and my son cranked the engine just two or three time, long enough for me to see the spark. Was a nice blue/white spark. I think I can finally rule out electrical problems and I'm good with my ignition coil and plug wires. pulled the fuel rail and swapped fuel injectors 2 and 4. We put it all back together, and could immediately hear the same rough idle and audible misfire, which I expected. My hopes were pinned on the code reader returning a 0304 Misfire Cylinder 4 but no luck - got the exact same code for Misfire Cylinder 2 even with the number 2 injector plugged in to cylinder 4 now. I've ruled out spark. I believe we have ruled out air, thanks to the valve job and the fact that while I keep trying to find a vacuum leak from a disconnected vacuum line, can't see anything amiss with any connection anywhere. I feel like I'm left with fuel as the problem, but swapping injectors did nothing, so I have to be missing something... which I just got an idea from Lee (getting some offline help now!) It could very well be the electrical signal to injector 2 itself. So, next up I will test that electrical connector to be sure it is actually sending electricity to the injector. As usual, I have to move on to other things today, so this is yet another To Be Continued. Hopefully I can check it tonight or one night this week and report back.
Did you switch number 2 cylinders spark plug with anyone of the other cylinders spark plug ?? Only reason I ask is that I read of a similar problem and it was the spark plugs resistance that was causing the problem.
I didn’t, and that is such an easy variable to test out I’ll do that as well. Truly at the point of willing to try just about anything. Sent from my iPhone using Tapatalk
It's interesting to watch this thread progress and the diagnostic process, but it's a bit of a guilty pleasure as I know that there is a MINI enthusiast out there suffering! Best of luck!
Maybe have some progress to report: I bought a noid light test kit and hooked up the test light to the electrical connector of the injector plug tonight. A working electrical connection will cause the test light to blink on and off continuously when the engine is started. I tested all four, and all of them blinked as they should when the engine was cranked and turned over. However, the plug for the injector on problem child cylinder 2 blinked for a brief time, but after the engine idled for maybe 4 or 5 seconds, the blinking light stopped. So my problem is electrical. Finally, I know something. But, what I don’t really know is what do I actually do next? I can’t see much of the wiring but what I can see of the two wires going into the connector appear to be visually fine. The big plug and socket under the cover on the right side visually appear okay too. But there’s a few feet of wire between those two ends where anything could be going on and it’s all covered up in a plastic tube. My first thought is to buy a new wiring harness and replace it. They’re about $360 but what I like even less than that cost is the fact that the entire wiring harness has to be replaced just to put in new fuel injector connectors. Looks like a bit of a job, but if I’ve come this far I’ll dive in and do it if that is the right thing to do. Am I missing other options to consider and try first? Sent from my iPhone using Tapatalk
Odd that the wiring harness/connections would work then not work. Could be a connector problem, hopefully not a wiring harness problem but might it be a ECU problem ?? Is it possible to read the signal straight off the ecu ?? If’n it is then that could save a bunch of time checking out wiring.
Good point. Now that think about it more, could it be that the light reads a signal at first and then doesn’t just because the ECU is doing it’s job and shutting down that injector because it has detected a misfire? If that’s the case then this isn’t caused by an electrical problem, probably, and is something mechanical since I’ve confirmed that I get a spark. The spark plug resistance idea is worth pursuing. I didn’t swap plugs last night after testing the injectors. I should just pull them and test the resistance of each to see. I’m also going to figure out how to check the pins in the ECU that correspond to the injectors. I saw a post on a different forum regarding that, didn’t fully understand it but I’ll find it again and see if I can figure it out. Sent from my iPhone using Tapatalk
OOMini had my same thought... If the problem were in the harness, I would have expected the light to either work or not work... not work perfectly until a certain state had been achieved and then not work (on a repeatable basis). That makes me think it's an ECU issue or, maybe more likely, a sensor issue. Is the car going into limp mode? Perhaps this is how limp mode is achieved (shutting down fuel injection to one of the cylinders).
Would be interesting to know if’n the ECU is programmed to shut one certain cylinder down if it receives bad signals from a sensor and not just random choice.
I would have to look in the Bentley manual but it may shut off fuel to a cylinder if the ECU thanks that cylinder is not getting spark to keep from washing out a cylinder and causing adverse wear. Does the trouble shooting section of the Bentley cover this?
I think before I start messing with the ECU, I would run the test agin and see if it acts the same way. Once the light stops blinking i would move the plug around and see if it starts blinking. if not I would wiggle the wires you can get to and see if it comes back on.