So. Did a search. Most recent info I found was from 04, and didn't help much so I thought I would ask again. I installed a buschur filter kit about a week ago. I only have the MAF adapter and filter, not the pipe as I hear the thing can wreak havoc without the right setup. Thing looks great, sounds awesome, and the car ran fine up until about 2 days ago.
Now, when I hit WOT, I will randomly hit about half boost (.5-.6 bar), to upwards of about 1 bar, with some erratic taper/spikes. The car will do it mostly in second gear, but has done so in first and third also. Again, it only does it some of the time. The rest of the time I will hit full boost, and the car runs just like it should. Is this normal? I know I need a tune, but I've never heard of having these kind of boost issues after installing an open filter. If the car was leaking boost would it ever be possible to hit full boost as I am doing? Or am I just being paranoid and this is something that a tune will fix?

 

It does sound like you are leaking boost. Are you on the stock BOV? Have you done a BLT?

 

Yes BOV is stock. Car is stock except for filter. Haven't done a test yet. I was throwing around the idea of putting the stock air box back in and seeing if that fixed the problem. Then I'd reinstall the filter and do a boost leak test.

 

So you only changed the filter, not the pipe? That will most likely not make a difference, as the filter can't 'leak' since it's job is to "leak" air through. Be sure to check all vacuum lines, clamps etc, and then do a boost leak test.

 

yep. only the filter. I didn't touch anything else though in the car, and I wasn't leaking boost before.

 

strange. I guess try and swap back to the stock box and see if that changes. the only other thing I can think of is that your maf doesn't like the new flow of air.

 

That's what I was thinking. Is it possible that under certain circumstances the car is leaning out too much with the new air flow and the ECU is turning down the boost as a precaution so things don't start breaking?

 

quite possible. which means that it is a "boost leak" but one caused on purpose by the ecu. if its corrected by reinstalling the stock air box, I would guess you just need a tune with the filter (seems odd tho) maybe clean the MAF?

 

i'm going to double check everything on the filter, and make sure everything is installed correctly. If it is, i'm swapping the stock air box back in and seeing if that takes care of things. If that fixes the problem, is it safe to say I just need a tune?

 

If switching back takes care of it, a tune should solve it.

 

ok. thanks for the help. Prob wont be able to do it til friday with work and all, but i'll let you know how it goes.

 

Ok cool just check back and update.

 

so I put the stock air box back in today. Did a few pulls. The improvement over the filter was negligible. It seemed like boost was more consistent and more in line with what I was expecting it to be, but still didnt convince me that there isn't a leak somewhere. SO, now i will be doing a boost leak test. Seems wierd though, it really only has the boost problems in the lower gears. I can throw it in 6th, stomp on the gas, and hold a steady 1.2 bar all day long... anybody else got any ideas?