As per the title, does anyone know the reason why MAF sensors fail in MY99/00 cars (especially when Induction Kits are fitted)???

Some people say it is due to the MAF getting 'clogged' with filter oil...
...and others say it's due to the vibration of an unsupported cone filter.

The reason that I ask, is because I have a Power Engineering K&N "Power Induction Kit" sat in a box at home.
http://www.powerengineering.co.uk/ac...R_FILTERS.html
I'd like to fit it back on the car to replace the K&N panel filter, as i like the induction noise it makes. However, I don't want this fitted if it's likely to cause another premature MAF failiure, and risk 'grenading' my engine.

PE said that they have never seen a 99/00 car with a failed MAF due to the fitting of their Induction Kit! - I find this a bit hard to believe!

 

As you've identified, either vibration from poor mounting or contamination from over-oiling cause the problems.

The newer MAF's (with a green spot) seem to be more resistant to vibration.

Richard

 

The K&N is actually very good (has a mouning bracket to keep it still) and I dont hink ive heard of one related to a MAF failure, although difficult to prove. Another reason for the MAF actually mis-reading is some cones alter the airflow to the extent that the MAF gets confused.... Hope you like the noise, I think they sound bloody horrible, esp when you lift off on boost. Wont do much for the power either, apart from a few BHP probably gained from leaning out the mixture slightly...

MB

 

My car has munched it's way through two MAFs... both showed signs of oil contamination.
MAF 1 was killed by a Pipercross Induction kit (sponge type which gets oiled),
MAF 2 was killed by a Blitz SUS induction kit... which is completely metal... NO OIL!!!!

I suspect that the oil is getting onto the MAF from air being passed back into the system from the dump valve. I also suspect that during the period when the dump valve dumps, that because induction kits allow a far better air flow, that the airflow over the MAF reverses and hence oil contaminated air can get to the MAF.
I've just changed my dump valve for a dump to atmosphere to see if it elliminates the problem - I have already noticed that the rush of air noise caused by dumped air is no longer comming from the air filter....

Anyone else have a view on this?

 

The Blitz is one of the worst MAF killers it would seem, and probably from vibration.

Oil from the DV is an issue, cant remember what the route the oil takes to get there, but it can be improved. If its just got oil on there, im sure it can be cleaned off, as long as its not completely caked. Im not sure the airflow is reversed, you need to have a look at what the angle of the DV pipe is, into the intake.

I would be wary of an atmos DV, most of the better tuners stay away from them... The ECU is expecting to see the air that would normally be dumped back to the box, and it gets confused, giving a rich mixture at that point (hence pops and bangs / flames at gear change) My MPG went in the wrong direction when I had one years ago... If its fitted properly, you shouldnt get any idle issues though.

MB

 

The Blitz SUS (no oil) also has coarse filtration, so you still contaminate it with dust, basically when a maf dies its through vibration or contamination of some sort.

As its K & N, as long as its mounted correctly should be ok but couldn't say if it would upset the maf scaling or not as I have never mapped a car with that specific one on that kept the maf. I know that the 57i kit normally does not cause any issues. PE should be able to advise though as they will have done a few I suspect, you say that they have told you it will be ok so what makes you doubt it ?

bob

 

The same thing I also noticed, itīs the oil coming out of the crankcase ventilation system which is blown onto the MAF sensor because of the air coming through the recirculating standard BOV. Iīve seen this happen with a few cars.

Mark.

 

Phoned dealer today.
ME; How much for a maf sensor for a version 5.
Dealer; A map sensor;
Me; No a maf sensor. M.A.F.
Dealer; Im not the usual parts man il ask the mechanic.
Me; O.K
Dealer; Mechanic said do you mean the airflow sensor?
Me; YES.
Dealer; parts person back tomorrow, can you call back then he knows what you want and when there comming in.

Bloody hell if maf failure is so comman surely they should of heard of one before.

 

You'll probably get a completely blank look if you ask a UK dealer for a MAF sensor for an STi5 (or indeed any import).

The airflow sensor is the same for all model year 99 and 2000 cars, so just phone them back up and ask for a price on part number 22794AA010.

 

That i could handle. But this dealer only deals in imports. Its where i bought the car in the first place.

 

Be prepared for another possible maf failure if you have fitted a vta bov, since the bov return is right next to the turbo intake then its not likely that would cause maf contamination however ... the head breathers do vent back very close. I fitted a pcv to my head breather return to stop it venting out but allow air to be drawn in.

 

BTW Mark been trying to mail you and always get bounced, think your isp has blacklisted one or more bt servers, can you/do you have an alternate ?

cheers

bob

 

PCV ?? erm... scuse my lack of intelligence.. but what is one of those????
Also excuse my lack of knowledge.. but where do the crank/head breathers come out???

Hoping to remove the whole MAF problem soon anyhow by fitting GEMS....

 

Hi Bob,

you can get me on my address in my profile, cheers. My work one is a bit fussy...

MB

 

Ritchie,

Id speak to Bob direct if you're going for an ECU change...

MB

 

STi7 previously running 4.36 volts MAF output at 1.1 bar dropped to 4.21 after fitting the Blitz..... -3.5 degrees at 5k2 on a previously clean car! If I'm going to be rescaling MAF, I will do it once with a sensible design - this one offered a brick wall, with ***** on (the bolts), to airflow

Bob - did you try a K&N set-up with standard sized MAF pipe yet? Be interested to know whether it required rescaling, and if the kit has a nice bell entry.

Richard

Edited to add: PS: PCV (valve) stands for positive crankcase ventilation, I believe. Basically it's an existing one way valve on your crank vent, I believe Bob used a second one for his purpose.

PPS: why is everyone so keen to remove the MAF?

 

PCV, also pressure control valve, yes its a one way valve as fitted to the inlet manifold below the throttle body.

Sorry meant trying to mail Mark V.

bob

 

Bob,

I received your last mail, I didnīt hear about any problems. Perhaps itīs due to the fact that I receive more virusses than E-mail at the moment.......

Mark.