Saturday, December 15, 2012 - 09:07 pm, by: Braden Tessier(Denemy)
My 92 TT has started making a strange noise when accelerating. It sounds like air being sucked in and a rattling noise. Had a look at the air filter, and there's no clasp thing holding it in place. Could this be the cause or is it something different? And what is the part called that clamps it on?
Tuesday, December 18, 2012 - 05:22 pm, by: Braden Tessier(Denemy)
There might be a hose missing, I'm not sure. I know very little about cars and the guy who had this before me was a total dropkick. The best way I can describe the sound is a slightly metallic rattle.
Thursday, December 20, 2012 - 06:03 pm, by: Kurt Atzmuller(Kurt)
Ok Mildura's a bit far for me to have a look! Are you getting any exhaust fumes while driving, if it was an axhaust leak around the turbos you'd be smelling fumes. Happenned to me not long ago. I didn't get any rattles though.
Thursday, December 20, 2012 - 08:00 pm, by: Braden Tessier(Denemy)
No nothing like that. I just got a roadworthy done about 3 weeks ago, so surely something like that would get picked up? I'm hoping it's nothing serious based on that anyway.
Thursday, December 20, 2012 - 08:21 pm, by: Chris Barclay(Chrisb)
Difficult to say if the BOV is connected correctly. Unless there's only the one blue vacuum hose under the hood. In which case the vacuum line of the BOV is connected to the plenum and this is correct. Whats been done with the original BOV, has that been removed and the connection blanked?
Thursday, December 20, 2012 - 11:17 pm, by: Chris Barclay(Chrisb)
Braden; where exactly is the other end of of the blue vacuum hose from the end of the BOV connected to? I thought earlier that it was on the plenum but I have identified both suspects (the two blue lines which appear to be coming from behind the PAS reservoir in the second picture) as the idle valve connection and the vacuum line to the FPR respectively. The kink in the red vent line could conceivably be causing pressure in the crankcase which can make the piston rings move in the grooves, in turn causing damage to the rings and overheating of the piston crown so you should get that fixed.
Friday, December 21, 2012 - 09:24 am, by: Braden Tessier(Denemy)
Chris, the blue vacuum hose from the BOV goes up to the turbos I think. In the very first photo I posted it is connected underneath what it shown in the photo. I'll get a new red hose hopefully tonight. Is there a specific type of hose I should get?
Friday, December 21, 2012 - 12:02 pm, by: Chris Barclay(Chrisb)
Braden; if the vacuum hose from the top of the BOV goes anywhere other than to the plenum (or to a tee in another hose which in it's turn connects to the plenum) then it's WRONG. The function of the BOV is to protect the compressor blades from the concusive pulse fed back through the intake pipework when the throttle closes. The way that it does this is to monitor (via the vacuum hose) the pressure in the plenum and when the plenum pressure drops (which it will when you close the throttle) the BOV opens to protect the turbos. There is also a spring in the BOV that works in parallel with the plenum pressure to hold the BOV closed. This spring compensates for the natural pressure drop through the intake pipework when the throttle is open and prevents the BOV leaking when you don't want it to. One of the most common mistakes in fitting a BOV (second only to putting it between the intercooler and the throttle body) is to connect the BOV vacuum line into the sensing port on the turbo which is used to control the wastegate. This results in the BOV always seeing turbo outlet pressure regardless of throttle position, the BOV never works properly and the turbo compressor is unprotected.
Almost any kind of hose is OK for the vent as it should be atmospheric pressure, you just have to look out for the temperature rating as the hose is right above the exhaust manifold and turbos. One of the best solutions I have seen is the one that's standard on the later model VVTi which is to use an elbow or banjo type connection on the cam cover and a straight hose to the intake pipework.
Friday, December 21, 2012 - 10:32 pm, by: Julian Mazur(Jules30)
It looks like the original BOV is in place and the vacuum pipe removed, the front mounted BOV may connect to the same place as the original one did, I remember when I changed mine, the vacuum line ran off a piece of metal pipe that came from the plenum. It's probably better to remove the BOV and blank both ends, it looks dodgy the way it is, as pressure will still be going to the original BOV but not releasing.
Just another thing, there's 2 schools of thoughts with pods. The first is they sound awesome and make loads more power, the second is they're cop bait, illegal and lose power.
It has nothing to do with your problem, however if you're planning on keeping the car, it's probably smart to change back to a factory airbox with a big mouth airbox mod, firstly, because you'll find vent to atmosphere BOV are illegal and if you're pulled for that, the pod will be next on the canary.
Sort out your bugs and fix the dipshit things the previous ower did and enjoy it.
Friday, December 21, 2012 - 10:52 pm, by: Braden Tessier(Denemy)
Thanks Chris and Julian for your replies. I'll take some better photos soon and follow the hoses and show exactly where they all start and finish, so hopefully someone can help me work out exactly what is going on.
I do want to change back to the factory airbox, it's just a little bit down on the list at the moment! Slowly getting there though.
Saturday, December 29, 2012 - 01:06 pm, by: Braden Tessier(Denemy)
Bit of an update here, the scraping/rattling noise has gotten a little worse. A few things I've noticed, the noise is only present when accelerating at an average speed. If I accelerate really slowly or put my foot down a bit the noise isn't there. Also it only seems to be present when the RPM gets to about 2000. It's also only there in the lower gears. Anybody have any idea what it could be?
Saturday, December 29, 2012 - 05:45 pm, by: Shane Haverkamp(Havabeer)
i used to have this noise, and so did a few other people, can't for the life of me remember what it was i don't think it was ever worked out.
but i do remember the noise your talking about at around the 2000rpm mark. there where a couple of other threads about it but i dont think anything conclusive was discovered. must just be a noise of the engine building up some revs in a higher gear