M135i injector failure after service

[RR50]

My M135i has done 10K faultless miles and has just gone in to BMW for an annual service. The car does a very low mileage so an inspection service was due because of age rather and miles. They have changed filters, oil and spark plugs. I picked up the car and immediately noticed a misfire driving when down the road. I turned around and returned it to them. They said it was probably a loose spark plug. The misfire was on cylinder 5 and they ended up putting another new spark plug and coil in to try and solve the issue without success. After waiting a couple of hours they told me they did not know what was wrong and kept it in over the weekend to wait for a senior tech to look at it today. The result being that they think it is a faulty injector and is unrelated to the service work.

It seems rather odd that a 10k mile car which is perfect in every way goes in for a service and comes back undriveable and it is supposed to be just a coincidence and not related to the service work.

Any thoughts on what could of happened here?

[Smuler]

RR50 said:

My M135i has done 10K faultless miles and has just gone in to BMW for an annual service. The car does a very low mileage so an inspection service was due because of age rather and miles. They have changed filters, oil and spark plugs. I picked up the car and immediately noticed a misfire driving when down the road. I turned around and returned it to them. They said it was probably a loose spark plug. The misfire was on cylinder 5 and they ended up putting another new spark plug and coil in to try and solve the issue without success. After waiting a couple of hours they told me they did not know what was wrong and kept it in over the weekend to wait for a senior tech to look at it today. The result being that they think it is a faulty injector and is unrelated to the service work.

It seems rather odd that a 10k mile car which is perfect in every way goes in for a service and comes back undriveable and it is supposed to be just a coincidence and not related to the service work.

Any thoughts on what could of happened here?

Probably stating the obvious, but how on earth couldn't they tell it was an injector issue, right away, when you first brought it back.
Whenever mine have failed, even the most general mechanic (recovery agent) figured it out, yet alone a BMW tech. Yet alone a Senior Tech. Even I had a good idea, in my case.

That makes me, cynically think something's a bit odd. Or they damaged it by accident.

Shouldn't likely fail at that age mileage unless faulty, surely? They don't cost much, why aren't they replacing?
Can you speak to the Senior Tech? That's what I'd do, I'd want to know what went on. Thinking they didn't fit a spark plug (i.e. it was loose) sounded a shambolic answer to me. Coincidences do happen, but it's a pretty massive one in this case if they're correct.

[RR50]

If it is an injector would it not at least have given some indication beforehand that it was on its way out (e.g. occasional misfire in the days before)? Coincidences do happen but to drive a car to a service with zero problems and then have a misfire occur immediately on collection is difficult to believe it is not related to the service work. Also how come the tech did not notice on the 4 mile test drive they did when it was serviced? It is just too much to swallow that the car was running perfectly up to the point I happened to pick it up and set off down the road.

I will try and get to speak to the senior tech working on it tomorrow. So far I have only spoken to the after sales manager.

[Smuler]

Just to add when 2 of my M3s injectors failed it was immediate, in every other instance as you suggest some warning.
That said , like you suggest it doesn’t feel right that’s it’s a big coincidence.
Might be worth seeking assurances all other injectors are okay.

[RR50]

Turns out that it wasn't the injector. Diagnostics said it was and they replaced it but it made no difference to the misfire.

In the end it was the spark plug in 5 which had already been replaced twice that was still at fault (2 new spark plugs put in which were both faulty). They concluded it must have been a bad box so replaced all 6 again to be on the safe side.

[anonymous-user]

anonymous said:

[redacted]

Idiot.

Unfortunately you won’t be able to do anything, a 4 mile test drive is not excessive, I’d expect the car to be warmed up and take at least to a NSL post any work.

[stevemcs]

anonymous said:

[redacted]

It’s the quickest way to get them up to temp so you can check the oil level after a service

[bearman68]

anonymous said:

[redacted]

Suitable user name.

[335dTot]

Service it yourself then.

[NicheMonkey]

anonymous said:

[redacted]

I don't have a problem with the young tech driving my FK2 at Honda I even said to him don't be shy with it, great guys they gave me a free MOT free wiper blades and replace cheap stuff on the car for free like the washer bottle cap that keeps falling off. I reckon if I went in with your attitude I would get nowt and they wouldn't be able to "fit me in" at my convenience or deliver the car to me for no extra charge.

We get a similar excellent service at BMW too! When ordering our second car we got a really good discount on the options, Try not being a tt and you might get the same!

[Zener]

anonymous said:

[redacted]

What a statement Really... so how are you supposed to confirm any other issues the car may have creaks/rattles running problems? they dont all appear by magic as stored fault codes you know , lets say the manual gearbox whines in 3rd or the auto trans slips between shifts etc dont expect your average Joe to notice faults with their own vehicles

[anonymous-user]

anonymous said:

[redacted]

You are* or you’re, apt username.

Well, when I’ve had work done on my car I expect it to be checked over, ran up to temp, ensure things have been replaced, torqued up correctly, etc, I’d rather a wheel fall off whilst the mechanic is driving it at 80mph rather than me.

Also any other potential issues and correct diagnostic can only be prevalent during use.