E86 - Strange sound when blipping throttle and sluggish revs

M

Maddysup

Member
Hi all,

Currently experiencing some strange symptoms with my 2006 3.0 coupe (N52 engine) and was wondering if anybody has experienced anything similar or has any advice on what it could be?

Symptoms are:

A very short sucking/blowing sound from the engine bay when the throttle is initially blipped/ tapped.

Sluggish, slow rising and falling revs when revved from idle and in neutral.

Slightly rough sounding engine.

Under gentle acceleration there's no sucking/blowing noise but still have the slow rising and falling revs.

The symptoms are intermittent and only occur on about 5% of journeys.

Symptoms go away when the ignition is cycled.

No change in performance, no misfiring, EML, smoke etc.

I've recently changed from a 30 mile commute to short runaround driving

I've added a video of the symptoms here ...

http://m.youtube.com/watch?v=MGuSQ3T38nA


Any input would be greatly appreciated! Apologies in advance if I've missed any newbie etiquette, I'm pretty new to forums. Cheers, Tom
 
I've not watched the video - on a bus - but it sounds like it could be a split in one of the rubber intake pipes. Reasonably common problem, and a cheap fix. Have a look at the hoses down behind the intake / sound generator. Could be completely wrong of course, but worth a poke around.
 
As Bing has said, check for split hoses as it has happened to me on my previous zed
 
Thanks chaps,

I've had a quick look for split hoses but couldn't see anything obvious. I thought something like that might be more likely to cause a constant noise rather than just a short burst, definitely worth a more in depth look though.

Could this also explain the sluggish revs and rough idle? Brian, is this something you encountered when you had the split hose on your previous zed?

What about the crankcase breather, could that also be a possibility?

Cheers
 
Update: with the weather warming up the symptoms have dropped away. I'm planning an engine flush and oil/ filter change as well as looking into oil separator issues. Will have the valve cover off withing the next couple of weeks and will post any updates pics and findings/ conclusions once complete.

In the meantime, if anyone has had oil separator/ crankcase ventilation problems, I'd be very interested to hear about the symptoms that you experienced.

Thanks, Tom
 
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