Guys any suggestions on what a brief flapping sound on cold start might be. A little like when fanning a deck of cards! Doesn't happen every morning lasts no more than 5 seconds and is not loud. Wont happen after work ( when stationary for 10 hours ). Is not currently overdue for service and only done just past 100k and generally drives very well. Suggestions...???

Could be the cam belt hydraulic tensioner, has the cam belt been changed yet?

timing belt was done 2 years ago but not sure about hydraulic tensioner.... seem to recall being told it needn't be done until next belt change

I'm sure you have already but if not check all moving parts for anything that might be touching or wrapped around something you may have picked up a bit of plastic wrap or something like that
Flapping does not sound like tensioner noise or rather I have never heard it described like that and from my experience I wouldn't describe it as a flappy sound
Try to get someone else to start it for you when you think it is most likely to happen to pin point the sound or start with the bonnet up already and race round after start up

Thanks for suggestion so have checked and nothing appears loose in engine. Sounds like coming from deeper in engine if that makes sense and whilst not everyday on start up seems more likely to occur on colder mornings... but that might be coincidental? Will keep monitoring and advise if anything changes, Thanks

try to take a video clip of the sound when it occur that way someone might recognize what the sound is!!

Most of the time is the pre tensioner, if you get the noise, stop the motor, restart. If the noise is gone there is your issue

Dont muck around with it either as I have here in my showroom what is left of the swing arm when the bolt broke due to this very issue being ignored way too long

Yes was pre tensioner and have had it fixed ....no more flapping sound!

https://youtu.be/baCqYnKnAZI
Not too sure if this is classified as 'flapping' but could be the same thing??
Just had the timing belt and belt tensioner replaced and now this sound came with it on cold starts.

Gates have admitted fault (on a friend's car) to the timing belt AND tensioner combo causing slack in the timing system (replaced at 105ishK KM). Most dealers won't change the tensioner on the first 100k service to avoid the drama, even though the part is rated to 100k working life according to the people we spoke to from Mitsu, who also advised us to go against the service manual and not to change it (it was too late at this point, it was already in the old parts box, on it's side, with pin in possibly breathing air).

When the engine comes to rest at a certain point the front cam rolls back and the rear cam rolls forward (even with the new gates glass belts) causing a the slack in the middle where the tensioner sits. If the engine starts in this state it will cause a noise - or in the case of my friend's '05 VRX pulls a tooth or two and does all sorts of great things. Thank goodness there was no bent bits. The tensioner and belt were replaced and set to spec, again, and it works fine to this day - fingers crossed.

The noise can be heard on both of our '05 VRX's on start up when cold occasionally and at high revs. Both with the brand new belts and tensioners.

On a noises note; he has recently replaced his EGR valve, no more obnoxious, untimed/out of timed/speeds up and slows down, ticking. It's lovely and quiet - I'm a bit jelly, but I'm not overly happy to pay $125 for a replacement part right at the moment as I am poor :( haha.

Just for my two bobs worth. Hope this is of help to someone.

:)

Gates have admitted fault (on a friend's car) to the timing belt AND tensioner combo causing slack in the timing system (replaced at 105ishK KM). Most dealers won't change the tensioner on the first 100k service to avoid the drama, even though the part is rated to 100k working life according to the people we spoke to from Mitsu, who also advised us to go against the service manual and not to change it (it was too late at this point, it was already in the old parts box, on it's side, with pin in possibly breathing air).

When the engine comes to rest at a certain point the front cam rolls back and the rear cam rolls forward (even with the new gates glass belts) causing a the slack in the middle where the tensioner sits. If the engine starts in this state it will cause a noise - or in the case of my friend's '05 VRX pulls a tooth or two and does all sorts of great things. Thank goodness there was no bent bits. The tensioner and belt were replaced and set to spec, again, and it works fine to this day - fingers crossed.

The noise can be heard on both of our '05 VRX's on start up when cold occasionally and at high revs. Both with the brand new belts and tensioners.

On a noises note; he has recently replaced his EGR valve, no more obnoxious, untimed/out of timed/speeds up and slows down, ticking. It's lovely and quiet - I'm a bit jelly, but I'm not overly happy to pay $125 for a replacement part right at the moment as I am poor :( haha.

Just for my two bobs worth. Hope this is of help to someone.

:)

Now I'm worried I raised this same issue in an earlier post as to having slack in the belt I found this when I was poking around ( had the timing belt cover off just to make sure the mechanic did actually replace my belt ) the jury was out as to whether the timing belt should have slack in it when the car had stopped
problem is mine only does in now and then and of course when the mechanic looked at it it was tight
I might run for a few days without the front timing belt cover and get some video footage and take it back to the mechanic

Now I'm worried I raised this same issue in an earlier post as to having slack in the belt I found this when I was poking around ( had the timing belt cover off just to make sure the mechanic did actually replace my belt ) the jury was out as to whether the timing belt should have slack in it when the car had stopped
problem is mine only does in now and then and of course when the mechanic looked at it it was tight
I might run for a few days without the front timing belt cover and get some video footage and take it back to the mechanic

Mine still creates slack occasionally due to the glass "flexless" belt. Haven't had any dramas, yet, but if the flappy/crunchy/tappy noise stays, then turn the car off. Normally it will show an engine light due to the timing being out - however didn't in my mate's car didn't. But you could certainly hear it. And showed a loss of power.