Funny noise from engine area

[philr]

Guys, any ideas on this one ? On my Chimp 500, when I accelerate hard I get a funny noise at about 5000 rpm. It sounds a bit like a sudden draw of air that occurs briefly when accelerating hard. IT ends up being 2nd and 3rd gear that I notice it in. I guess 5000 rpm in 4th and 5th would be some silly speed that I can't legally do on the roads. It seems to come from the passenger side of the engine bay (which happens to house the air intake pipe). I wondered whether the engine management system recognises the hard acceleration and decides that there is a need for more air for some reason (presumably legitimately). I don't think that it is a serious problem as I don't get any feedback from the wheel or pedals etc. I'm just curious. Cheers Phil

[fordy]

when was your air filter last changed??? Maybe the engine is sufforcating a bit at high revs.

[philr]

Don't know really as I have only had the car for 8 months. I presume that Fernies checked that when I bought the car. I'll have a look at the weekend. Its just a bit of a wierd noise really and I'd like to understand what/why. Cheers Phil

[Dr chuff]

Could it have been your passenger? Dr C

[GreenV8S]

Maybe an air leak somewhere between the air filter and the throttle. This duct is under a slight suction at high revs/full throttle, the rest of the time it is more or less at normal atmospheric pressure. If the filter was blocked that would increase the suction. Peter Humphries (and a green V8S)

quote:Guys, any ideas on this one ? On my Chimp 500, when I accelerate hard I get a funny noise at about 5000 rpm. It sounds a bit like a sudden draw of air that occurs briefly when accelerating hard. IT ends up being 2nd and 3rd gear that I notice it in. I guess 5000 rpm in 4th and 5th would be some silly speed that I can't legally do on the roads. It seems to come from the passenger side of the engine bay (which happens to house the air intake pipe). I wondered whether the engine management system recognises the hard acceleration and decides that there is a need for more air for some reason (presumably legitimately). I don't think that it is a serious problem as I don't get any feedback from the wheel or pedals etc. I'm just curious. Cheers Phil

[philr]

quote:Maybe an air leak somewhere between the air filter and the throttle. This duct is under a slight suction at high revs/full throttle, the rest of the time it is more or less at normal atmospheric pressure. If the filter was blocked that would increase the suction. Peter Humphries (and a green V8S)

This certainly sounds more like what the noise is. It is only at the top end of hard acceleration and is a bit like a suction noise. I didn't know whether there was a pump/suction unit in the air intake system, but it does make sense for times of hard acceleration. Do you think that this is just "standard" operating behavour or something that may need looking at ? cheers Phil

[GreenV8S]

It's only an air duct, there's nothing special about it. As long as the replacenment is about the same diameter and doesn't leak you should be fine. Peter Humphries (and a green V8S)

quote:on the same thread, does any one (or Peter Humphries) know if it would cause a problem by removing the pipe between the mass airflow meter and filter and fitting an aftermarket item. I know this will do bugger all for performance but mine gets a hammering from the bonnet stay and looks like it could be causing airflow probs.