Air Intake -40 Degrees
 

Hey Everyone,
I have a 99 Porsche Boxster with 64K miles. The performance has gotten pretty bad, and the check engine light came on, so I took her to a mechanic someone recommended. They said the mass airflow sensor is reading -40, the mechanic hooked up a new one (Bosch), and the temp was still -40. There was also a code that coil 3 misfired. I am guessing the two are related (maybe the low temperature reading is causing her to run rich). But if it is not the MAS, I am stumped.
I ran a search in here and on Google with no results. Anyone seen this before?
Thanks,
Jonny

i'll take a stab. there is an iat (intake air temperature) sensor that plugs in to the intake manifold. this is where the computer gets it's air temp info from. if it is unplugged, shorted to ground, covered in goo, or just failed, it might be sending a signal so far out of whack that the computer is just defaulting to a minimum value (-40). the iat sensor is #17 on the diagram below:

Intake Distributor

Hate to have to correct you, but that is the engine compartment temperature sensor; the intake air temp signal comes from the MAF.

my bad! thanks for the info. cheers.

A problem in the wiring ?

While were talking mafs mine threw a code a few days ago. P0102. I cleared it. Waiting to see if it returns. I have`nt cleaned it in the almost 3 yrs that I`ve had it. I started to source a new one did`nt know the price. Why is there such a swing in the price of them ? I know dealer is well. But online from $ 50 to $600. WTH ?:confused:

The mechanic hooked up a new Bosch MAF, and said the readout was still -40. I cleaned it and cleared it, and it just came right back. Anyone know where I would start for the wiring?
Thanks,
Jonny

Yea, I noticed the crazy price range online too. $250 from Bosche, $500 from Porsche, or $50 from China...
Let me know how it goes if you pop one in.
Thanks,
Jonny