Pre-notes - car is 100% standard apart from a resonator delete, Forge BOV and the air filter I shall be talking about.

 

So, I have fitted an open air filter to my car and been monitoring it over the past few weeks using my OBD live information.

 

I have noticed over the past couple of days that the characteristics of the BOV have changed. And I'm wondering why, so any insight/ideas would be nice.

 

When I put my foot down at the moment, it dumps a tiny bit of air before starting to pull. You can hear it and its a very short 'tsch' noise.

 

It only seems to dump when I am at higher RPM or I pull really hard at low RPM. Previously, anytime you lift off the throttle, it dumps like a bus airbrake.

 

The amount of air being dumped sounds like its less than it was? Can only go off sound here, as I'm not truly sure.

 

Downshifting when high in rpm used to produce a small dump too, that has now gone away too. 

 

I'm going to put the standard airbox back on and see if these characteristics go away. I'm just puzzled because its been on for 2 weeks and its only just started to change. The performance of the car is still the same. 

I spoke to a guy I know who is a VAG fanboy and he told me that changes to the intake can take a while to make a difference since the ECU takes time to realise it's getting more/less air and adjust accordingly. Not sure how true that is, either.

 

Just looking for thoughts and potential reasons for the above scenario happening. If you've nothing constructive to write, runalong.

Edited 10 December, 20205 yr by AmusedMussel
Typo

The fanboy told you the partial truth, it takes about half an hour of mixed driving for the wideband lambda readings to alter the dynamic map if the ECU has been reset.

However changing the air filter isn't going to do anything at all unless the old one was very dirty and a noisey BOV is a purely cosmetic change, so...

Well, the old one was nearly new. Changed in August.

 

I'm not sure if I am just being paranoid, because its now making different sounds. Can you think of any reason it might be different all of a sudden? 

Perhaps I should be looking at the BOV, seeing if there's anything wrong with that?

Well, the silly BOV is designed to be noisey so it's entirely likely that you're hearing things you just couldn't hear before.

And regarding the feeling that its not ejecting as loudly as normal?

20 minutes ago, AmusedMussel said:

And regarding the feeling that its not ejecting as loudly as normal?

 

The BOV only has one simple job to do which is to vent excess pressure from the inlet plenum, if yours is adjustable you could try tightening it slightly otherwise there isn't much else you can do other than revert to the standard setup which recirculates that same excess pressure back to the airbox quietly.

I wondered if I had a vac or boost leak. Just took it out for some hard pulls from various speeds and got peak boost @1.3bar and peak intake manifold pressure @2.2bar. So they look ok to me.

 

i like the induction noises, but don't want to hamper performance. Been monitoring intake temps and found that an open air filter gets about 4-5°C higher than ambient temp outside. So, will do the same data logging on the standard airbox and see what the difference is.

Managed a 6.6 second run to 60mph yesterday, so, can't be anything wrong with it. Going to put it down to paranoia

Wasn't paranoia. Had a lose boost pipe from the BOV. After spending far too long in the rain with some ridiculously stiff jubilee clips, they're all on tighter now