E39 M54 2.5 Rough Idle

[Foxhole Norman]

So........my rough idle problem. I unplugged my MAF after I finished work at 11 on the off chance this was causing it, ran perfect from dead cold albeit with revs a little higher at around 900. Would this indicate it's faulty or dirty? There was no code for the MAF when the car was scanned with INPA a few weeks ago.

[rebel.ranter]

I'll scan it again for you this evening if you want. Just give me a text.

[Foxhole Norman]

I'll scan it again for you this evening if you want. Just give me a text.

That'd be great, I'll give you a shout after lunch when I'm out of college. I already have an intake boot for the MAF on the way to replace the old one, will see if this sorts it before I even think of changing the MAF.

[Foxhole Norman]

Big thanks to Mark for checking the car out again, it seems that the coil I put in a few weeks ago sorted the misfire. The only other codes is being caused by the light switch, which I have already and the other was a failed to burn, which we assume happened when I replaced the coil as there has only been one instance of it.

Looks like the idle is caused by an air leak after all.

[mac7]

I had a small split on.the boot, I fixed it with a puncture repair patch and some algimatination tape for a short term.fix worked a treat

[Jazz]

And there I was, thinking I'd have a rough idle buddy for a while :-D Air leak hunting for you so?

[Foxhole Norman]

I've had this problem since I got her, about time to be sorted :tounge:

I have a new intake boot ordered for the MAF as the current one has electrical tape covering cracks/cuts which must be the leak, if not, out with the Soapy water!

Jazz, check all the hoses leading from the MAF, that must be where yours is going wrong! Or maybe the MAF itself!

[mac7]

The only sure fire way to check is to remove the boot and squeeze all corrigations as that's usually where it let's go.

[Foxhole Norman]

The only sure fire way to check is to remove the boot and squeeze all corrigations as that's usually where it let's go.

New one should be here in 2/3 days anyway so will be going in regardless, I will check out the lower boot and some of the other more fragile pipes.

[rebel.ranter]

Definitely worth changing the intake boot & the switch for the brake pedal. The DME showed up loads of occurances of the brake switch plausibility error.
Error 240, Burning Fail showed one occurance on cylinder 6, the one you changed the coil on. Remember that's one occurance since last reset.

Discussion on the code here with mention of rough idle at cold start up:

http://www.bimmerforums.com/forum/showthread.php?2061018-M54-cylinder3-misfire-Asking-for-help-advice

Here's a similar "error 328 burning fail" issue on a different cylinder, replacing the coil seemed to solve it:
http://www.bimmerforums.com/forum/showthread.php?2061018-M54-cylinder3-misfire-Asking-for-help-advice



Here's another one with the same "error 328 burning fail", it looks like this was down to a leak on the intake:
http://forum.bmw5.co.uk/topic/84196-error-code-decipheringwhat-actually-is-the-fault/

Yours definitely needs replacing, it was well cracked, that tape on it is not air tight. We know that needs to be changed anyway, so that's what I'd change next.