[byd02]

Hello, so this is my first post here so go easy

I have a BMW F30 328i 2012 model, it has 183,000 Kms on it (almost 114,000 miles). I had the car for 14 months with zero issues. However, last week, as I started it I noticed the check engine light on and the car was shaking and shivering like crazy. Drivetrain malfunction in the dash as well. I took it to the mechanic and we started troubleshooting. Misfire was on cylinders 1 and 2 so we did the old swap trick, we switched the injectors of 1 and 2 to 3 and 4 and vice versa. The misfire moved to cylinders 3 and 4. Easy right? well not so much. I replaced all 4 injectors (with the exact same new parts) and all 4 spark plugs (just in case) and reset the adaptations and drove it around. No issues and no check engine light. The next morning, I turned it on, again nothing wrong problem seems fixed. Today, I turn it on in the morning and the issue is back. Check engine and misfire. If I drive it for a few minutes, then park, stop it, start it again, the drivetrain malfunction goes away and the car seems "normal" again.

I have already bought new ignition coils and I think I will try these next. But what drove me crazy is how the fault moved to the other cylinders when we swapped the injectors! It seemed logical to conclude it was faulty injectors!

Also, when I make the drivetrain malfunction error go away the car seems very normal and does not lack power upon throttle. I drove it at very high speeds (124 mph / 200 kph) and there are no issues there. It seems the problem is upon starting it only (when it is cold). I don't know for sure.

Please assist me.

[CarlosC]

Can you run a scan on it to figure out what (if any) error codes might be coming up?

[byd02]

Hello,
I ran a scan yesterday, and now the misfire is on cylinders 1 and 4. The errors are:
"Misfire on cylinder, fuel injector switched off" --> For 1 and 4
"Fuel air mixture too lean"

[IraHayes]

What is the reading on your downstream O2 sensor? Actually, on both sensors for that matter.

[Blemus2061]

Which injectors did you get eu5 or eu6 piezo injectors. From what I remember parts catalog on etk at the dealers was in correct. Need to run a test module to see which style injector you need looks the same when you compare them to each other. After replacement need to register injector numbers to DME to calibrate then clear adaptation values. Keep in mind that when you are installing the piezo injectors you should avoid tapping them in as it can damage them they are pretty sensitive.

[byd02]

I just took out the injectors that were in the car (that were running with no issue for 14 months) and swapped them with the same exact part but NEW.

[Uriavita]

hope someone can help you to solve your problem.

[sspade]

Originally Posted by byd02

I just took out the injectors that were in the car (that were running with no issue for 14 months) and swapped them with the same exact part but NEW.

Can you share part number?

[IraHayes]

Originally Posted by byd02

I just took out the injectors that were in the car (that were running with no issue for 14 months) and swapped them with the same exact part but NEW.

Did this resolve your problem?

[byd02]

So for those who will find this thread in the future:

The reason for the misfire was a bad O-ring on the injector. This was allowing air to leak into the cylinder and consequently causing a misfire. When replacing injectors, make sure to replace the O-rings surrounding them as well (In my case, they were sold separately). Car is running fine now, no more misfires at cold starts and at all. Thanks all for your help!