[Markyh5]

Hi All!

I just picked up my 2015 focus st Diesel last week. I want to change the air filter do you have any recommendations on what one to get?

I've seen some things about the RS lid as well? I've seen this one on eBay pretty much the same just without the RS logo?

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thank you in advance for your help and advice

 

[Phill P]

There's a thread on here somewhere recently where the diesel was fussy about airfilters and kept going into limp mode (K&N).
Unsure what he/she/they/them ended up with though.

New ST3 Diesel Air Filter Upgrade

Hi, Just picked up my brand new 2018 Focus ST Diesel and decided to stick in a K&N filter that I had in the garage. I have an ST petrol and bought two K&N's for it last year, one with the sealed end and the other with the open end and bung! Have fitted open ended one to my black ST3 petrol...

www.focusstoc.com

 

[Markyh5]

i have seen mixed reviews about the limp mode... think I'm just going to stick with the lid and wack and st badge on it to make it look a bit more pleasing under the bonnet for now. as knowing my luck my car will be the one that plays up with a new filter

 

[Markyh5]

There's a thread on here somewhere recently where the diesel was fussy about airfilters and kept going into limp mode (K&N).
Unsure what he/she/they/them ended up with though.

New ST3 Diesel Air Filter Upgrade

Hi, Just picked up my brand new 2018 Focus ST Diesel and decided to stick in a K&N filter that I had in the garage. I have an ST petrol and bought two K&N's for it last year, one with the sealed end and the other with the open end and bung! Have fitted open ended one to my black ST3 petrol...

www.focusstoc.com

thank you! by the looks its just a standard air filter with the rs lid to increase air flow thank you for your help

 

[WayneST-2]

I’ve got a K&N Filter and RS Lid on my 2015 ST Diesel, no issues with limp mode. Much deeper sound with the RS Lid.
I’m sure you’ve read plenty on here already about how fussy the diesel is when changing filters and the lid, seems to vary from one to another, not really sure why.
It’s just a case of trial and error, maybe try the lid first with the standard paper filter, if all ok, then maybe try the lid with a K&N or Pipercross filter.

You may also get differing results depending on whether you’re running the factory map vs Stage 1/2 map.
I believe mine is running the factory map but never had it confirmed or run on a Dyno.

 

[Markyh5]

I’ve got a K&N Filter and RS Lid on my 2015 ST Diesel, no issues with limp mode. Much deeper sound with the RS Lid.
I’m sure you’ve read plenty on here already about how fussy the diesel is when changing filters and the lid, seems to vary from one to another, not really sure why.
It’s just a case of trial and error, maybe try the lid first with the standard paper filter, if all ok, then maybe try the lid with a K&N or Pipercross filter.

You may also get differing results depending on whether you’re running the factory map vs Stage 1/2 map.
I believe mine is running the factory map but never had it confirmed or run on a Dyno.

I've ordered one off eBay looks like the RS one but don't have the branding but as you say it depends on the car so think taking it one change at a time is the best way to go to see what my car do/don't like.

by the end of the year, i want to stage 1 map it as even though the car is quick standard I do feel ford could have got more from the engine

 

[sttwoton]

Stock air filter with the RS type lid works fine, after all, that’s how the RS comes from the factory.

 

[Markyh5]

Stock air filter with the RS type lid works fine, after all, that’s how the RS comes from the factory.

That’s true I know it won’t sound as good as an RS or Petrol ST but hopefully it will sound better

 

[gbgaz]

Performance air filter in a diesel?? it's literally this lol.....

As Wayne has said.. some will take them some wont and go straight into limp as soon as you put your foot down... switch off it clears, then comes back as soon as you put your foot down again! A lot of standard cars run fine on a performance filter for ages... then get mapped and go straight into limp... it's all just so random!

 

[Markyh5]

Hopefully it will only take one try 🙏🏼 But yeah all about trial and error