Just had a long discussion with the makers of heated film air mass sensors ( as used in the Z ). An issue that has been identified on production vehicles is that carry over of oil from oiled air filters can lead to drift problems in the flow sensor or even complete failure.

Most of the time we don't see the drift as the exhaust gas oxygen probes can trim out mixture errors - however in the longer term the sensor can drift so far as to produce errors.

The heated film is around one micron thick and so is very fragile and damages easily. Even moisture from poorly designed intakes "could" lead to a failure.

This could invalidate your warranty, i suppose if the dealer noticed the change.

I have NOT seen any doccumented failures and am simply passing on what the manufacturer said - make your own judgement.

 

you have to drench the filter in oil to experience such a problem, unless its a poorly made MAF (like in the 99 Subarus)

 

No, we arn't talking about drowning the filter - simply the normal oiling as fitted to the MAF sensor manufacturer. Problems are even occuring with the slight carry back of mixture and oil from a motor that isn't in perfect condition.

Apparantly the new generation of Diesels with electronically metered fuel injection are a particular issue as they don't have exhaust EGO probes to do any mixture correction caused by any oil or dirt disposition.

 

REDZED is correct. Many GTI's have had this issue. They have to lightly oil the filter and make sure that they clean up any excess. My friend with a GTI has already replaced the MAF twice with the stock airbox and filter. He just recently installed a CAI with my help and is watching it very carefully.

 

I too had problems when I installed an aftermarket pre-oiled filter (K&N). My car (Jetta VR6) would hesitate when accelerating. Among other things, they replaced the MAF once.

Someone on this forum suggested that it is because VW's suck, which may or may not be true, but it has scared me enough to avoid pre-oiled aftermarket filters on my Z.

However, it seems that many on this forum have used K&N filters, and have experienced no difficulties.

Cheers,
Sherman

 

Aren't most filters oiled so some extent? The stock paper ones feel oily to me....
Mika

 

Its amazing just how little oil it takes to produce a change in the MAF's output. On a MAF test bench you could see the sensor begin to drift when the standard paper/epoxy filter was changed to a brand new ( an correctly oiled ) aftermarket unit.
The reason why there are no short term effects on driveability is that the EGO system has substantial mixture correction capability, but this "could" be exceeded in the long run. Once again I saw the results of a filter change on the ECU fuel trim via a vehicles ODB2 diagnostics port ( not a Nissan ).

Once again - I havn't heard of a problem of this type on a Z, am just posting this so we can all make educated decissions, and perhaps avoid a warranty situation......

 

Just use a dry filter like Blitz... I've installed one in my Z and have no issues.

 

Have seen the Blitz filters in boxes, but not in real life. Are they "dry" and if so how are they cleaned etc.
Whats your opinion - worth any extra power ? ( and do you have a part number and source for a Z ?)

 

I had to replace the MAF once on my MR2 spyder due to my AEM intake w/ K&N filter. I cleaned the new one each time I changed my oil w/ brake cleaner, and never had another problem. My friends 99 impreza MAF would go bad if you farted while the hood was up.

 

The following quote was taken from another post where this issue was brought up and a poster asked if there was a safe was to clean the MAS without damaging it. My concerns and questions follow.

OK, I've got some questions regarding this that hopefully someone can help with. I'm a bit concerned now, as I run the Stillen intake which puts a very large oiled conical K&N filter directly in front of the MAS. I've cleaned and re-oiled it once using K&N cleaner and oil and following the directions closely. I made sure to wipe off any excess oil from the filter areas and even blot the surfaces of the filter lightly to take up any excess oil. I haven't had any problems, but I'm a little worried.

1. Can you give an example of a good non-residual contact cleaner?
2. Would denatured alcohol work?
3. Is it a good idea to periodically clean your MAS in this way if running an aftermarket oiled filter?
4. Will cleaning it over time damage the MAS?
5. How much is it to replace the MAS if you f@&! it up?

 

 

Uh, diesels don't have MAF sensors, they don't even have throttle bodies. They flow all the air the engine can pump, the injected fuel quantity determines the torque output.

 

Sorry but the current generation of common rail electronically metered diesel injection systems DO have MAF sensors - you are thinking of the old type truck diesel systems.

The current generation of automotive diesel systems are quite different from those of the past, using solenoid injectors fed from a common rail high pressure - continuous flow pump, and with an injection computer doing all the work. Bosch is very much at the cutting edge of this type of system. They also have throttle bodies - although this is not new on diesels

 

OK...so I've just swapped out my stock air fliter for drop in K&N (which I've used in most of my cars, trucks & suv's)...now what...or is the concern mainly with cone filters???

 

which is exactly why i would never put any of those AEM / INJEN CAI systems on my car... even a K&N Drop in filter!!!!

anything that "could" go wrong WILL GO WRONG!

the dealer ship near me has seen this happen a couple of times...

 

No - its with ANY form of oiled filter and heated film MAF sensors, but not doccumented as a problem with the Z. As I first indicated, other vehicles have had these types of problems but there does not ( yet ? ) seem to be a Z issue. No doubt IF it occurs someone will post. In the meantime I am going to put a Blitz filter on the tester to see what happens.....

 

when you re-oil the filter that is when this will happen...

how many on this board have re-oiled the filter?


the oil that comes on the filter is pretty well set in and probably not going to drip...

 

I replaced the air filter on my 911 with a K&N and ran into this issue. It is a known problem with the 911's Mass Air Sensor. The oil from the filter and damage it, and cause the check engine light to go off. Most of the people recommend that you open the plastic package that the air filter comes in and leave it out overnight (preferably on some news paper) before you install it.