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Steve
Steve, Vehicle technician
Category: BMW
Satisfied Customers: 1103
Experience:  Garage owner for thirty five years
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High 1 series 1.5cc with 37,000 on the clock, sorry 2016

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High 1 series 1.5cc with 37,000 on the clock
JA: What is the model/year of your BMW?
Customer: sorry 2016 118i has misfire code comes up with cylinder 3 so I put new plugs and switched the coils around and still misfire on 3
JA: Have you seen the misfire code before? Has the car been stalling?
Customer: Not stalling feels like car holds back when driving then the same code comes up
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: Yes so I’ve done the plugs and moved the coils around but always says cylinder 3 misfire but gave the car a good hard run and was fine for about 30 mins
JA: Anything else you want the Mechanic to know before I connect you?
Customer: I’m fitting new fuel filter tomorrow just to check that no water in fuel?

Hi thank you for your question, my name is ***** ***** I am a fully qualified vehicle technician with over thirty years in the trade, hopefully I can help.

There are a few reasons that may cause the problem and starting with the easiest first, I would check the connecting plug to the coil pack, these can cause problems, you should also carry out a compression test just to be sure the fault isn't a valve (but I wouldn't expect this).

If the connecting plugs look good, and as the fault did clear momentarily after a run, I suspect the injector may be at fault. First check the connecting plug to the injector.

There have been problems connected with the injectors and you may be lucky and a new filter and possibly an additive will solve the problem, but if not you may be looking at having the injectors serviced, I would if this is the case get all the injectors done, to be sure.

I hope this answers your question but do please feel free to ask any further details by replying to this thread.

Many Thanks

Steve

Customer: replied 1 year ago.
Steve would I not get different code if was injector fault???

Hi

No an injector will cause a misfire, what is the code you are getting?

Steve

Customer: replied 1 year ago.
Po303

Hi

Yes that is a cylinder 3 misfire and could be due to:

Engine mechanical fault ( valve)

Injector / fuel system

Or electronic control (ignition or ECM)

It is also listed as possibly being a MAF sensor but I am not convinced that would give a single cylinder misfire and would suspect a multiple misfire from a MAF

Steve

Customer: replied 1 year ago.
What about if I try switching around the injectors to see if the fault is moved to another cylinder?

Hi

You can try that, but the book time to remove the injectors is 1.75 hours so not a quick job. If you have the time this may help to narrow down the problem.

Steve

Customer: replied 1 year ago.
Ok job for weekend then but one more thing is when I first looked into the fault codes it did come up as po300 po302 and po303 but that was only the first time multiple misfires and missing on cylinder 3 and 2????

Hi

One of the problems with the BMW system is that it will make attempts to compensate for mixture differences in the cylinders, this means that the ECU will richen or weaken the mixture to each injector by changing the injection period according to the reading from the 02 sensor, this can cause a mis diagnosis sometimes due to the mixture on one cylinder being reduced or increased to compensate for the adjoining cylinder.

This would explain the multiple random misfire codes.

I hope this makes sense, but do please ask any further details.

Steve

Customer: replied 1 year ago.
Ok so if I switch the injectors around this will be ok to try?

The detail I have do not show the injectors on your BMW to be coded, so this should be ok to try.

Steve

Customer: replied 1 year ago.
Ok good thanks

Your welcome, I hope all goes well.

Steve

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