P0102 CEL Code won't go away.
 

So I bought this 2002 Boxster S about 4 months ago now. It developed an idle hunt and CEL about a month and a half after I bought it.

Originally I didn't mind, until it slowly got worse.
The idle hunt got extremely consistent so I finally decided it was time to fix it.

I do work for a specialized German Shop and therefor have great access to tools and parts!

I first checked the codes. The only one was:

P0102- Mass or Volume Air Flow Circuit, Low Input.

My other scan tool read the same code as "Hot Film MAF Sensor"... No idea wtf that means...

However; I proceeded to smoke test the intake, coming up with a leaking oil filler tube. Replaced that and seemed to remedy the problem for a day. When the idle hunt returned the next morning, I smoke tested it again, and found no more leaks.

Through the last few months I've smoke tested the intake a total of 4 times after fixing the leak, hoping another leak would develop which it never has.

I have also:
-Replaced the MAF sensor with an new OEM Unit
-Mapped all the Oxygen Sensors which map out perfectly.
-Replaced Spark Plugs (Due to mileage and desperation lol)

Maybe some one else has found this problem? Help :(

I kept getting the usual codes for the SAS (left and right bank) and it finally went away when I replaced the vehicles battery. It was bad and also the wrong type for the car. PO installed a 48R in place of the required 94R.

I installed the 94R (optional battery) which is what it must have for the Tip. Most of the Boxsters use the 48R which is marginal for our cars. Others have stated that 94R is the correct one to use as 2005MY and up use this as a standard. The two codes I used to get said it was to lean or low which dawned on me that the reference voltage was too low. This may seem to be your issue with a too low of a reference voltage. Either battery voltage or bad connection/ poor ground. Just a thought.

p0102 can also be for open circuit or short to ground, uncertain what you have for scan tools, but if you hook up a durametric to can view the actual signal coming from the maf. see if there is any signal at all, or a signal too low (as per definition of p0102). rev the car and see if the maf signal swings. you might have a bad wire someplace (no maf signal) or your replacement maf was bad also (low signal). good luck.

Hmm... most cases involving P0102 are a direct result of a bad MAF sensor . And, the situation is usually remedied by replacing it with a new one. As TRK mentioned, it may be that you have a defective sensor .

Tried yet another MAF Sensor, and the light still won't go away.

I can read sensor voltage from my scan tool and of course it spikes from about 4% to 10% upon the idle surge, but I assume that is only because something is telling the car to adjust throttle position, as throttle position, and demanded load also change by about this much.

Are there any other common problems that cause an idle hunt in boxsters?

Possibly Oil Separator?

Air leaks... From my experience they're horrible to diagnose:(

Yeah I thought so too, but I've never had one hide from me when using a smoke tester. Great little tool.

Are there common vacuum leaks that I should know about?