Misfires in N20 Engine

D

DaytonZ4

Member
 Dayton O, USA
I have a 2015 28i with the N20 and 8 speed DCT.

Had misfire about a year ago. Quick scan showed cylinder 3 misfire. There were several: codes a general code for misfire, code for cylinder 3, general code for fuel injection deactivation, and fuel injection deactivation for cylinder 3. I assume the fuel injection deactivation is to protect the engine and catalytic converter.

Swapped coil 3 for coil 1 and misfire moved to cylinder 1 so, I replaced all 4 coils AND spark plugs. Had slight rough idle before misfire but not bad - just noticeable. Otherwise, car has been running fine for past year.

Got misfire this morning on cylinder 1. Same four codes: 2EFE - misfires several cylinders, 2EFF - misfire cylinder 1, 2EE0 - misfires several cylinders fuel injection deactivation, 2EE4 - misfire cylinder 1 fuel injector deactivation. As stated before, I believe the fuel injection deactivation codes 2EE0 and 2EE4 are to protect cylinder and converter.

I have noticed over past year or so (even before the cylinder 3 misfire last year) sometimes odor from exhaust, like a sulfur smell which tells me fuel/air mixture is not right and the catalytic converter is causing the smell.

Only maintenance on the engine since replacing all coils/plugs was oil pan and valve cover gasket replacement a month ago.

I do not want to believe ignition coils fail this much and I am starting to suspect it was not the coils to begin with, even though that appeared to be the case. Before I try swapping them around, what else could this be and why did replacing coils before fix the problem the first time?


Kind regards,
Carl
 
If it’s the sames codes as before and that fixed the issue, don’t rule out coincidence. Were they good quality parts?

Start with what you do know. Then work out what you don’t know.

That would be my approach.
 
Thanks for replying, Reamesy. I got the parts from FCPEuro, so I assume they are decent parts. I can try to check if the ignition module is bad by probing for control voltage to the coils. Given there has been a strange odor before the first time this happened, I was leaning towards clogged fuel injectors, or a fuel delivery problem. But that doesn't make a lot of sense since the problem appeared resolved for over a year - it doesn't mean that's not the problem, but I feel like I'm missing something (or over-thinking it).



Kind regards,
Carl
 
Get a decent scan tool that can plot multiple PIDs. Look at the readings. A good scanner will show a normal range of if it’s out of spec you should see it.

It’s not going to tell you what’s wrong but will help you focus your efforts which should allow you to target the culprit otherwise you can waste money throwing parts at it.
 
The scan tool I have should be able to do that, but will have to wait until tonight when I get off work. I'll post an update once I figure it out. I've never used the function so, I might have to fiddle with it for a bit.


kr/Carl
 
When does the misfire occur ?

Idle

Any time

Hard acceleration
 
@B21: Took a day off; but to answer your question, it initially happened upon acceleration onto the highway, but thereafter, as soon as the car was started. However, after taking the day to simmer down, I went out to troubleshoot. Here's what I found:

I first changed the coil with a known good one (I saved them from last year). Cleared codes and car ran fine. Checked fuel pressure and it was erratic but averaged around 13.5 MPa (around 1990 PSI for us Yanks). That seemed way too high for idle speed.

Anyway, went under the hood and listened to each of the injectors. Number 1 sounded louder than the rest, but all were in rhythm and ticking along just fine. Then I accidentally touched the connector/wires for the Number 1 injector and car immediately started misfiring. So, I shut it down, and checked the connector - it was not fully seated. Reseated it and checked the rest. Cleared codes again and restarted. Car ran fine. Fuel pressure still erratic but much smoother graph. Overall running pressure was down to 10.6 MPa (1545 PSI). I feel like this is still too high for idle speed.

Took the car out and opened her up without incident. So, I believe the misfire issue is fixed. As I mentioned in the OP, the valve cover gasket had been replaced and I'm wondering if the tech that did the work just didn't fit the connector back on properly.

We're going to take it easy over the next couple of days before trekking out on longer drives just to make sure all's good. But now I have another question: Is the fuel pressure at idle too high? I feel like it is since I believe it should be closer to 4.7 - 5.0 MPa (680 - 725 PSI) at idle and upwards toward 13.5 - 20.5 MPa (2000 - 3000 PSI) under load/driving - I didn't check this. Considering there's 116K on the clock, it probably means the injectors are choking up might need to be replaced. What do you fellas think? Could my scan tool be reading it wrong (or doubling the reading for some reason)? Or maybe the pressure sensor is being wonky. I'll have to go get a mechanical gage and tap into the fuel rail to know for sure, I guess.

Thanks for your replies and suggestions.


Kind regards,
Carl
 
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