Air filter clean - problems

[johnbkidd]

I cleaned my K&N filter and now I have no revs above 2,500.

I don't think it is the filter as I have replaced it with a new spare paper one - same low revs. 

Any ideas?

 

[Gabbo]

check around the air filter housing that you havent dislodged or disconnected any sensors connectors. (MAF sensor should be somewhere close to here).
Check the connection after the airbox to the intake to make sure it doesnt need retightening as some diagnostics can detect a leak after the air filter if there is no intake system deperession.

 

Do you have any indication of error codes, warning lights etc when the revs are limited?

 

 

In a diesel you shouldn't really need more than 2500rpm anyway...  

[Robbijay]

Oil on the MAF sensor from where you re-oiled the K&N, forcing it into limp mode?

[johnbkidd]

I will check further - but I don't think there are any odd air leaks.  And I will check the MAF for leaks...  No error codes indicated on the screen (don't have a proper tester for codes).

I have not done a road test - perhaps it has just run into 'safe mode, limp home' out of pique!  And usually I don't use high revs - but an auto halt at 2,500 is odd.

Thanks so far.

[johnbkidd]

2 minutes ago, Robbijay said:

Oil on the MAF sensor from where you re-oiled the K&N, forcing it into limp mode?

 

Hi - the filter seemed dry - no excess oil.  But it could be.

Will MAF auto clean I wonder?

John

[pist0nbr0ke]

My 2016 vRS TDI DSG won't rev over 2500rpm in park or neutral, never has done IIRC.

 

Have you driven it yet?

 

Don't think it will be in limp mode without the engine light coming on...

[cheezemonkhai]

Sounds like the MAF sensor.

Had similar on a mk2 after I had removed it to get to something and forgot to plug it back in.

 

plugged it in and it sorted it.

[johnbkidd]

2 hours ago, cheezemonkhai said:

Sounds like the MAF sensor.

Had similar on a mk2 after I had removed it to get to something and forgot to plug it back in.

 

plugged it in and it sorted it.

 

2 hours ago, cheezemonkhai said:

Sounds like the MAF sensor.

Had similar on a mk2 after I had removed it to get to something and forgot to plug it back in.

 

plugged it in and it sorted it.

 

[johnbkidd]

Hi all  - and thanks

My French neighbor who likes 'motors' and I played... we extracted the filter, decoupled the filter box, the housing for the MAF, took that off and found nothing untoward. I did not have an electric cleaner spray- so MAF remains uncleaned.

The hard plastic grid on engine side of MAF box was a slightly sooty, but not the onwards pipe into the engine.  The air-side side of MAF box was totally clean.

Rassembed, refitting all little pipes, using the new paper filter - turn-over OK but stationary still did not exceed 2,500 with foot flat to floor.

Uncoupled the Tunit device and reverted to standard VAG - still the 2,500 revs.  Recoupled the Tunit.

Took it for a short trip and returned though my village at up to 4,500 revs - all no problem at all.  So it works on the road!!!  But stationary again, it maxed out at 2,500.

 

BIG question.  What revs do the MOT testers need to check the exhaust- so many secs at xyz-revs?  And higher than 2,500 I guess.

I will ask VAG garage later in nearest big town.

Meanwhile thanks for all your answers.

 

 

 

 

[Robbijay]

3 hours ago, pist0nbr0ke said:

My 2016 vRS TDI DSG won't rev over 2500rpm in park or neutral, never has done IIRC.

 

Have you driven it yet?

 

Don't think it will be in limp mode without the engine light coming on...

Pist0nbr0ke mentioned this a while ago, think MOT test is over 2k for fast idle so you should be ok (unless you need to get it higher to pass!). I suspect VAG will have designed the engines with MOT in mind though, so don't worry about it.

[nickytheshaft]

I hope you soort it out. 

You should stick with stock air filter and change theme twice a year. 

I saw videos with dyno test of aftermarket oil filter, no gain at all.

Mann paper filter are cheap, I paid mine 18 euros. At least no maf issues.

[gregoir]

Iirc you can not rev a modern VW group diesel more than 2500 in neutral. My Mk2 Octavia was like that. It helps during emission testing , possibly.

[ords]

My 1.6 tdi won't rev above 2500 rpm in neutral

[cheezemonkhai]

Yeah there is a limit on the static idle, related to the MOT emissions test.

 

2500 sounds about right for this. 

 

If it revs fine when you’re moving, I would suggest your car is fine.

Edited 5 June, 2018 by cheezemonkhai