BMW e46 Rough Idle - Video

ImDave

Hi Guys,

I just bought a BMW e46 (3 Series) 2004 1.8L petrol from a dealer on Monday evening. Only 49k on the clock, car in excellent condition etc. Been running great since Monday.

However - tonight I have noticed it is running rough when idle. The rev counter needle will bounce up and down within a small range, sometimes quickly in a short period of time. It definately wasn't doing this before tonight as when test driving I left it at idle for a good while to see if the engine ticked over consistantly.

I have taken a short video and put on YouTube in the link below which explains better.

https://www.youtube.com/watch?v=zuGN-BD9-N0

From doing a bit of research, the MAF sensor or an air filter/flow issue seems the most likely culprit. I am really annoyed about the whole thing as I was really enjoying the car up to now, and even though it might be something small, it's still annoying. I have a three month engine warranty on the car, so will probably go back to the dealer over the weekend, but just wanted some opinions here in the first instance.

Thanks.

obezyana

As you said it could be MAF it could be throttle body, idle control valve, could be intake boot, damaged piping. Bring it straight back and have then fix it. Simples

ImDave

obezyana wrote: »

As you said it could be MAF it could be throttle body, idle control valve, could be intake boot, damaged piping. Bring it straight back and have then fix it. Simples

Cheers - I think that is the best thing to do, just wanted to have an idea of the problem in case they try to bluff.

I'd imagine the car is ok to drive for now presuming it is one of the above faults? Probably won't be able to get car back to them until Tuesday now with the bank holiday.

obezyana

To be honest I can't say if it's ok to drive as I don't know what's wrong nor do you so I'd avoid driving it if you can. Plus driving it like that is not good for fuel consumption.

pandaflop

lookup how to clean the maf, easiest job on a bmw, other culprit not mentioned for a rough idle could be the coil pack, this would also result in a kind of hesitation in acceleration, the bimmer forums have a lot more info as its a common problem

Alfagtamini

i had the same issue with my old e46 318i last year.

the oil filler cap was not fully tight, removed and refitted and it solved the issue.

ImDave

Cheers guys, I rang the dealer the other day and he was very accommodating in saying to bring it back into him and he'll get it sorted. I haven't had a chance to do so yet however.

The oil filler cap sounds like a possibility actually - the car was serviced just before I collected it and I the issue wasn't present before then when test driving.

I will check this out tonight, and if it's not the oil cap I'll just return to garage next week. I watched the video on cleaning the MAF which looks really easy too, but I will probably just leave back to the garage instead.

ImDave

Just to close off this issue - I brought the car out to the dealer this morning and his mechanic checked it out straight away. Within a couple of minutes the source of the problem was found, which was a cracked air hose/pipe which was messing up the fuel/air mixture, causing the erratic idling.

All sorted within about fifteen minutes and covered under the warranty. Very happy, can now really enjoy the car