FAO tfb - flutter noise
 

hi. I hope this message finds you well

Just a quick one after reading your replies to other peoples posts you seemed to most knowledgeable and best to ask. I have a GV 2.8 CRD 2005 model. Ever since I have owned the vehicle... About three years now it has made a fluttering, spitting like noise when accelerating under load then when the auto box changes down a gear it vanishes. The noise usually is audible at 2k revs but soon as the box changes down a gear it stops. Also this only happens of I accelerate slowly and labour the engine. If I floor it it doesn't happen. I thought initially it was a leak somewhere but the car runs perfectly... No loss of power.... No hesitation.... No exhaust smells etc. it runs like a dream. I have noticed it seems to be associated with the position of the accelerator pedal. During the times when the noise is audible if you either release the pedal or push it down a bit more the noise stops. if I press and release the pedal continuously in one motion over and over the fluttering noise comes and goes at the same position of the accelerator pedal. I hope this makes sense. As I have said it has done this since I have owned the car about three years and in no way affects performance. Just curious as to what it may be or if this is a common noise. Also the noise is not loud at all. You have to listen to hear it. Thanks in advance for any info you may have or anyone else who might know anything.

hmm...not something I have come across. Don't suppose you could record the sound with your phone? It's very hard to describe a sound :)

Regards
Richard

Obviously not the engine. Sounds like you have the engine chattering on something like engine mounts or exhaust. Front mount aft of radiator comes to mind which is more a rebound mound on engine power take up.

I also hear this noise and think I know what it is. As the air filter is on the drivers side, when you accelerate you can hear the air being sucked in but when you slow down or momentarily take your foot off of the throttle after accelerating that excess air isn't needed so you get the flutter noise you mention. Next time you drive try and listen and pinpoint it and I could bet it's coming from the air filter.

http://www.trak-life.com/wp-content/...h-1024x682.jpg

- not good for the turbo [cavitation] the back pressure forces the air back through the turbine blades

Yes that's correct QinteQ. A quick amendment to my post is that it comes from the air filter area and also that it only happens at very low speeds for myself. Still pulling well for a 200,000 mile car but I imagine what ever type of blow off valve this system has might be getting past it.

Chrysler along with all domestic vehicle makers will have installed a relief valve, how good after 200k miles it still functions may need to be investigated. A BOV is essential for the [high & low/slow boost application] long term protection. Its usually only higher order petrol heads that get involved with BOV's, I would not want to deviate from a stock Chrysler fitted spec.

compressor bypass valve [CBV]
air by-pass valve, bypass valve [BPV]
blow off valve [BOV]