Audi A5 Forum & Audi S5 Forum banner
1 - 16 of 16 Posts

·
Registered
Joined
·
436 Posts
Discussion Starter · #1 · (Edited)
All,

This weekend I received my BMC filter from BMC and performed the install.

The package was shipped pretty fast and it was cool to see the made in Italy all over the box since I haven't had much aftermarket parts or really anything where I have noticed it was "italiano." :D

Took the filter our of the box and its a K&N style cone with a red surround, metal cap at the end that says +20 HP... Its incredible.. It feels like it!!

haha Made you look..


Actually, after unscrewing the air box 4-6 screws (Torx), and gently manuvering the cover off, I pull the stock paper filter out of its zone and removed it.. Nothing rocket science here..

When you do reinstall the BMC, note that you will most likely have to use a little bit of WD40 or water around the ring of the filter on the inside OR the outside of the air duct because it is a tight fit when its totally dry.. Spray a tiny bit of WD40 and let it run all the way around the filter inner ring and it will pop on the connecting air duct to the air intake..

Don't forget to clean the inside of the air box while you are at it a wet rag.. Soap and water will do if its really dirty.. Mine was very clean but of course, I only have 3000 mi on my S5 and I'm in a pretty dirt free environment..


Performance:


According to accounts and reports, the BMC is supposed to provide 2 HP increase over stock....(????) I don't know about this, but you definitely will not notice any increase of power.. It won't be substantial. I think in the the long run it will provide more flow for my AWE + downpipes and it will definitely perform better..

After installing the filter, when I started my S5, it actually started to chug and almost lose some idle and then it reset itself and resumed the idle at a more regular pace.. I must admit it got me a little concerned because in my mind I was going, "oh man, here we go with the whole leaning out the mixture, too rich, too lean... on and on, forever etc.."

I'm thinking that because of the MAF detecting a higher intake flow, the engine hasn't had time to adjust to the possibly leaner (??) mixture due to the intake?? I drove to work but that is only 2 miles from my house so still, I can't tell if the S5 has adjusted to this yet... I'll post up any new comments on this.

Anybody else notice a slight drop in throttle response after the BMC and then notice it pick back up once the car "learned" it? :cool:
 

·
Registered
Joined
·
821 Posts
I am thinking of changing mine... so will be following this one :)
 

·
Registered
Joined
·
1,730 Posts
I mistakenly ordered the K&N filter - mistakenly because theirs are shipped pre-oiled. Before fitting, all the oil had to be thoroughly removed with de-greasant as apparently over time, particles of it become detached and fly onto the MAF sensor, gradually clogging it and causing lean running.

That done, it was a fairly straightforward fitting process as you say. Can't claim to have noticed any flatering on start-up tho' - in fact I'd be surprised if there were sufficient airflow at idle for the MAF sensor to detect any difference?

In general driving, can't claim to really notice any difference at all - I think it's more placebo effect, emphasised by the rather nice K&N stickers on my airbox cover!
 

·
Registered
Joined
·
436 Posts
Discussion Starter · #4 · (Edited)
I mistakenly ordered the K&N filter - mistakenly because theirs are shipped pre-oiled. Before fitting, all the oil had to be thoroughly removed with de-greasant as apparently over time, particles of it become detached and fly onto the MAF sensor, gradually clogging it and causing lean running.

That done, it was a fairly straightforward fitting process as you say. Can't claim to have noticed any flatering on start-up tho' - in fact I'd be surprised if there were sufficient airflow at idle for the MAF sensor to detect any difference?

In general driving, can't claim to really notice any difference at all - I think it's more placebo effect, emphasised by the rather nice K&N stickers on my airbox cover!
HAHA Indeed.. Call it.... "Placebo Effect 2009"

Indeed, it must be noted to be very careful with oil on the filter..

ESS, do you know if the S5 has to relearn fuel mix ratios if you disconnect the battery? Doesn't make sense i know but that is the only thing that I did other than just swap out the filter... On startup it kinda chugged a little but I think now after analyzing this that I had inadvertantly hit the accelerate pedal and maybe all i experienced was a slightly flooding since i depressed it accidentally..

Also, I have a ECU remap and that may play a part... I'm thinking that if anything, after 20 or so miles it will have a chance to readjust for the fuel/air ratio that has changed due to the BMC.... After my ECU was remaped, it did take about 20 to 25 miles before the S5 had learned the new settings (and I noticed a substantial difference.. hence, the remap.)
 

·
Registered
Joined
·
1,730 Posts
Hmmmm (rubs chin thoughtfully, mainly to hide the fact that he hasn't a clue.....).

Mine too was remapped, albeit some time before the filter was fitted. I can remember post remap simply leaping into the car, roaring off and beaming all the way home - again, I wasn't conscious of any 'learning' period whislt the ECU perfected it's behaviour in its new environment, but it makes sense and I think I recall some similar discussions around this elsewhere on the forum.

Honestly with the filter, I think that the airflow improvement is likely so marginal that any difference would be accommodated within the 'normal' envelope of the data the MAF sends the ECU, which would be akin to other variances you may get in high/low heat/humidity, i.e., heavy traffic or thick smoke.

I'm sure Ian will be along shortly to give me a stern lesson in air/fuel equations........
 

·
Registered
Joined
·
2,046 Posts
Ian here!

...14.7:1 that's all you need to know!

...Regarding the 'stutter' after installation, like Ess, I doubt it's down to differences in airflow, at idle, there will be no difference at all. I expect it's more likely to be a little moisture from when you cleaned the airbox and possibly some WD40!! ;)

The BMC filter I have found just helps the engine rev more freely and respond better. No one will notice 2% power increase anyhow, but the overall feel of the car is a willingness to provide power right up the rev range, and since installing, I have hit the limiter a few times, which I rarely did before, because the engine always 'felt' like it wanted you to change gear by about 6,000RPM.

In short, high-flow airfilters come into their own when the car is gobbling up air at high-revs like a fat football fan at the pie stall.

My view, an engine is only as good as it's weakest component... so like buying expensive guitar leads, why not invest a little bit more in making sure that this part is not hindering performance?
 

·
Registered
Joined
·
198 Posts

·
Registered
Joined
·
436 Posts
Discussion Starter · #8 ·
All,


Can you recommend an over the counter autoparts solution for cleaning the MAF sensor? Somebody recommended regular rubbing alcohol (isopropyl alcohol) but I wondered if there was stuff I can buy at Autozone or Pep Boys etc.. ?
 

·
Registered
Joined
·
436 Posts
Discussion Starter · #9 ·
All,


Can you recommend an over the counter autoparts solution for cleaning the MAF sensor? Somebody recommended regular rubbing alcohol (isopropyl alcohol) but I wondered if there was stuff I can buy at Autozone or Pep Boys etc.. ?

Nevermind, I remember that CRC electrical parts cleaner at Autozone/Pep Boys is one of the best to use for a MAF sensor..
 

·
Registered
Joined
·
1,413 Posts
Just to add; Be very careful spraying WD40 anywhere near the airfilter box. Use some other form of lubricant such as a slightly soapy finger (i dont know). The oil will contaminate the MAF and kill it. The same applies to the oil on K&N filters too.
Green Panel filters are the best ones to use in this case as they are not oiled.
 

·
Registered
Joined
·
436 Posts
Discussion Starter · #12 ·
Just to add; Be very careful spraying WD40 anywhere near the airfilter box. Use some other form of lubricant such as a slightly soapy finger (i dont know). The oil will contaminate the MAF and kill it. The same applies to the oil on K&N filters too.
Green Panel filters are the best ones to use in this case as they are not oiled.
Vouch for this 100%.... On my BMC filter, be extremely careful, I barely used some WD40 on the rim of the filter and somehow the vapor of it, or something floated in the air and onto the MAF... It chocked the MAF out a little bit and while it did burn it off it took a couple of days to dry and it was driving a lot slower.. Just be careful when you do this.. I didn't un-oil the filter.. The purpose of this filter is partly to trap particulates of dirt and dust that pass through normal paper filters.. The oil purformes this function.. Take the oil away and yes it does block sand and dirt but it doesn't block dust as well..
 

·
Registered
Joined
·
2,046 Posts
I would also encourage those who choose the K&N over the BMC... DO NOT remove the oil! The filter is oiled to trap the dust, rather than trap it in paper like the std... this is how they achieve better flow. BMC on the otherhand use a larger surface are by presenting both sides of the cone to increase airflow.

The K&N oil and the MAF sensor really depends on the airbox design and mounting position of the sensor... some cars suffer, most don't. I guess only time will tell with the S5... unless the posts above referring to issues are refering to the S5/A5?
 

·
Registered
Joined
·
436 Posts
Discussion Starter · #15 ·
Is this a cone filter? If so, does it install inside the airbox?
It is indeed a cone filter and its easily installed INSIDE the airbox with the lid on of course :)
 
1 - 16 of 16 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top