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Hello all,

I have a several questions about the Mass Air flow sensor. I have a MY 99 C2. I also removed the the MAF and this is the part#

996 606 123 00, I had Porsche pull the records for my car and it turns out it was replaced late 2003.

1. How do I know if my MAF is starting to go out?

2. How do I know if my car has egas and this is the correct part#?

3. what is the average life span of the MAF ?



Edited by SlvrSurfer
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1. Usually the car will run very rough and likely throw a CEL.

2. For a MY99 C2 (no egas) that is the correct part number. (Current retail price is $433.38).

3. Without excess oil from over-oiled aftermarket or other debris damaging it. Most likely 5-10 years minimum.

When my car was under warranty the dealer replaced the MAF when they didn't need to. Problem was actually something else - so it can be mis-diagnosed.

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You car does not have Egas. Get yourself a scanner. You should not be without one if you drive any newer car. You will be able to read the air flow that the MAF is registering. The MAF can last a long long time, or it can go bad in a short amount of time. Elements in the air that pass over the sensor can sometimes make it dirty and it will not function propery.

I am a believer that too many MAF's are replaced unnecessarily. You can clean the sensor by spraying it with an electrical cleaner and letting dry. I personally have cleaned mine in the Porsche and other cars by simply pouring rubbing alcohol over it and letting it air dry. I have 45,000 miles on my car and still have the orginal MAF.

If your MAF goes bad, you should get a check engine light. Your scanner will be able to determine if the fault is caused by the MAF.

You can get the exact Bosche MAF sensor ffrom several auto supply outlets and on the internet for less than $300.

Edited by 1999Porsche911
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Thanks Loren and 1999Porsche911 for all your insight and advice, but this is just one variable that I am trying to eliminate that stems from a hunting/rough idle problem that I have been having for quite some time now. I've tried a few things with no changes, cleaned throttle body for carbon build up, ran fuel injector cleaner, and cleaned MAF. Any other suggestions would be appreciated.

Thank You Again


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Hello PTEC,

Yes, last week I was at the Porsche Dealership Michael Stead in Walnut Creek and they hooked the PST2 with me watching and checked out fine. Is this what you mean by faults stored on DME? I have had no CEL go on. Also I seem to notice lower than normal oil pressure reading when the engine is fully warm-half of the time registering at 1.4 or 1.5 at a stop- with outside temp averaging at 45-50 degrees(Walnut Creek, California).



Edited by SlvrSurfer
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As I tell everyone who owns a newer vehicle BUY A SCANNER.

As far as the idle hunting...have you carefully checked every vacuum hose? If so, do it again. Make sure the air tube to the throttle body is on properly and secure. I would try resetting the computer to start from a clean slate. Get your radio code out because you will need to enter it after you reset. Disconnect the negative cable from the battery for 5 minutes. Then reconnect. Start your car and let idle for a few minutes and then go out for a drive. The car will run a little rough at first as the computer learns the proper settings. After the car warms up, your idle will probably stay high (around 1100) until you go through a few drive cycles, but it should not be hunting.

Also look at the Idle Control Valve that is attached by 2 screws to the left side of the throttle body. This unit controls the amount of air that passing into the intake when the throttle is closed. There is a little window in this device that can sometimes be cleaned (I use carb cleaner) which will flush out any grit that has found its way into it.

One other thing I have seen cause a hunting idle, not just in the P-cars but in other cars as well, is a bad water temperature sending unit. This sensor tells the computer what the engine temp is and sets the idle accordingly. This is located directly below the air filter housing and is a 4 conductor sensor that is screwed into the water pump housing. You might try simply removing the connector from it and then putting it back on to insure a clean fit.

The scanner you will be buying should be one that will not just reset any fault codes, but also display the following readings:

Fuel Trim, Engine Temp, Engine Compartment Temp, Timing, MAF, all 4 O2 Sensors and Engine Load.

Keep us posted.

With your oil level at FULL, it is normal for the pressure to be as low as 1.5 at idle on a fully warmed engine. It should be above 4.5 when above 3,000 rpm's tho. Remember that these water cooled engines don't care what the temperature is outside. Your oil pressure should be the same on hot days and on cold days.

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I had a hunting problem and a number of things were said to me by an OPC & specialist :

1) Maf (mentioned)

2) Faulty o2 sensors

3) A split hose (mentioned)

4) Check the oil filler cap (?) apparantly if its loose or the rubber seal has perished or cracked on the inside of the cap, then this can cause hunting.


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I use an old one that is not available anymore. Just make sure it can show you real time readings for the following: Engine Load, MAF, O2 sensors, Fuel trim (short and long), timing, engine temp and engine compartment temp, It should also report a freeze frame of the engine condition when a CEL is set. You can get one for about $150 or less.

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