DR

Hi Gang,

Just finished a phone call with a fellow 928 owner. He was complaining of black smoke and rich running conditions from his 95 GTS !! Had already replaced Temp II sensors, checked for vacuum leaks etc, etc.

My first question was are you running a K&N filter, the answer was yes. My answer was the platinum wire in your Air Mass Sensor has been pre-maturely fouled from the oil used on the K&N filter and will need to be replaced ($400++). He said "funny you mention that as I had noticed the platinum wire was black and BTW, how did you know that was the problem. I thought the Air Mass Sensor is self cleaning ".

I said "Easy, you are the 3rd person in just the last week to have the identical problem. The Air Mass Sensor was designed to burn off DUST, not oil ".

Those of you that know me well are aware of my feeling concerning K&N filters in a 928. I have always said they allowed much more fine dust particles in your engine and that they have been dyno proven to NOT increase HP (some have even seen less HP with K&Ns).

This newest reason is the strongest reason yet, especially for 928 owners with LH fuel Injection (84-86 Euro S and 85 and later US)

We have also never sold them, never will. We try to explain this to 928 owners calling to buy them on a daily basis. It seems that 90% of new 928 owners think the first think to replace is the factory filter with a K&N ... WRONG !!

Just an FYI, you have been warned (again) !!

Mike Schmidt

I took my K&N filter off soon after first installing it, because of a fine oily film I found it causing. The subject once came up with a Porsche mechanic I was talking to. He said that in his opinion K&N filters should be illegal to use on cars with hot wire airflow sensors.

John..

I have one on my 1981 928, but I don't have the hot wire on that car, it is the old flapper door AFM. Strange though, my 1993 Audi S4 has one and I have not had any problems....it has the hot wire sensor.

It may have to do with the location of the sensor in relationship to the filter. If I am correct, the sensor on the 928 is below the filter, so any oil coming through the filter will get there regardless. On my S4, the filter is below the hot wire sensor and I have had no problems. The previous owner had installed it on the S4.

Perhaps I should switch?

Max

DR, why couldn't a person simply remove the screen on the MAS and clean the wire with a swab and M.E.K. or Acetone (all found at Home Depot)?

Either one of these products would clean the heated wire and not leave a oily residue. Not knowing whether it would work, I think I would try it first before shelling out 400.00+ duckies!


Just a thought

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Max

DR

Hi Max,

[quote]Why couldn't a person simply remove the screen on the MAS and clean the wire with a swab and M.E.K. or Acetone (all found at Home Depot)?
Either one of these products would clean the heated wire and not leave a oily residue. Not knowing whether it would work, I think I would try it first before shelling out 400.00+ duckies! <hr></blockquote>

It is always worth a shot, but "many have tried... and many have died".

Seriously , that little wire is fragile and I do not know of anyone that has sucessfully and properly cleaned that wire with out damaging it to where the sensor did not work properly or at all.

This does not mean however that it can't or hasn't been done..

Mike Schmidt

The wire is heated to red hot when the sensor goes through it's burn off cycle, so the oil gets pretty well baked on. The platinum wire is less than .003 inches in diameter. It would probably break well before all the baked on residue could be removed with solvent and a swab.

Randy V

It may be like trying to clean a lightbulb filament Max. Success is highly unlikely.

Max

It was "Just a thought"

<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Max

John Struthers

Hmmm... we have been here before.
After my initial questions on this issue some time ago I was determined to see if I was suffering from the the dreaded oil film problem.
With the stock filter, related or not, I was running rich. Tapped it and used compressed air to blow it out from the reverse ( back )side.
Still rich. Put on the K&N, still rich. After the debate, pulled the K&N, Oil filming!
Put the K&N in a black plastic trash bag and left it in the sun. Then took the gooey filter out and thumped it on a soft old bath towel, wiped it down and no problems with vacuum induced oil stripping/misting since. Nor dust, nor bug parts, leaves, weeds, nails, BurgerKing wrappers, old refridgerators, nothing! To each their own...IMO
I do think there is WAY TO MUCH filter oil being used here. The guy with the big C.I. turbo diesel truck -ancient post- WILL ALWAYS pull more vacuum and in his case I would have some reservations.
As to the hot wire, you are the guru, I don't even have one so I shall defer to yuor opinion.
But, if you have one of those fouled wires - is it mounted in a bracket of some sort - send it to me and I will try to find a way to clean it without causing further damage. Not a solution to the PROBLEM, but if it saves a sHARk owner a couple hundred bucks , let's give it a shot!
John S. <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" /> <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />

Greg86andahalf

If I were to clean a thin wire, I would try and soak or saturate it with solvent without rubbing or wiping. I had a copier with the thin wire which came with a tool which looked like plastic jaws with felt on each side. You were supposed to clamp the wire and rub back and forth across the it. It always felt like the wire was going to break. I switched to a method of spraying the wire with solvent and letting it dry. Just semed safer.

Just a thought.

DR

Update :
Just received a call from the GTS owner that prompted my original post.

He reports his GTS is now running perfect and feels stronger than it ever has after replacing the Air Mass Sensor and throwing the K&N in the DUMPSTER !!!

Normy

Good lord!

I've been running the K&N for the three years I've owned the car, and have had an on-again/off again rough running condition...

I've looked at my MAF wire extensively, and indeed it appears to be black [I have very good eyes]. I can even see what looks like a fried bug wing [hot sauce needed?] hanging off of it. Yes, the screens are in place.

My rough running situation disappeared temporarily when I refit the car with Nology wires...only to be replaced with a sudden complete miss...which has disappeared as of late. In its place, the partial miss at high power/ low RPM is back...and when I look in the rear view at night [car headlights behind me], I can see quite a bit of black smoke when the car is missing.

What do you think? Does this add up to a fouled MAF sensor on my '85 Euro S2?

Normy~

'85 S2 5 speed

LastV8

Ran a K & N in my 88 928S4 for 2 1/2 years without any problems.

DR

Norm,
[quote] What do you think? Does this add up to a fouled MAF sensor on my '85 Euro S2? <hr></blockquote>

Sounds like it is very possible, I would try to find a local 928 owner(w/LH injection) that would let you try his first to be sure.

LastV8,
[quote] Ran a K & N in my 88 928S4 for 2 1/2 years without any problems <hr></blockquote>

"Ran" sort of sounds like past tense. Out of curiousity how many miles did you put on it during this period and do you still own that 88?

Have great 928 weekend,

Thom1

Hi Dave,

Thanks for the informative post. It is good that you are posting more often now. I see your input about products as beneficial to the 928 community. This should not be construed at all as spam. For the 5 years that I have owned this car, you have supplied excellent advice and solutions on many occasions. Jeannie has gone beyond any normal expectations to help out. Wally has provided great technical assistance.

I had never heard the mass air sensor contamination issue before. I like your Dune reference. I too have tried and died. I read in, if memory serves, the shop manuals that the wire should be cleaned periodically. I was foolish enough to try it. The wire is an extremely thin filament. It will break if you put practically any pressure on it.

Maybe it is time to get rid of the K&N. It has been on the car for about 5 years with no problems. The instructions specify light infrequent oiling. It could be easy to over oil that thing.

Keep up the good posts!

Thom Ross
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