Tossed OBDII Code: P0103 (MAF)

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Tossed OBDII Code: P0103 (MAF)

Postby Gordy » Sun Dec 26, 2010 1:59 am

I tossed this code today, just curious if anyone has experienced it as well, and possible things to look for.

2007 MX-5 w/ ~45k miles. CAI, full Goodwin exhaust/header (that's about it for "engine" parts)

What happened:
Merging onto highway for today's commute to work. Got on it a little, but not overly hard. Had just up-shifted to 4th, and still on the throttle a bit (I'd say 60-80% throttle, shifting around 5-6k), when the car lurched (loss of power) for a split second, and the code came up.

Was raining out (ahh, Seattle life), and a lot of moisture in the air (cars in front of me). My hunch was I sucked up some water and burped the MAF sensor. I haven't checked the sensor out yet (it's after midnight, bit late to make noise), but will check wiring and maybe remove the MAF and clean it with brake cleaner.

I did have my ScanguageII running at the time, and just happened to have my MAF gauge running on it. Thinking that maybe that could be a cause of a thrown code (for god knows what reason), I swapped the gauge to something else. I cleared the code prior to the return trip home.

No code tossed after that on the drive home (~35 miles).
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Re: Tossed OBDII Code: P0103 (MAF)

Postby jboemler » Sun Dec 26, 2010 12:40 pm

The SG connection won't cause a thrown code. SG (and any other OBDII monitor) merely requests info from the car, and displays the result. There has to BE a code in the car in order to get one back. It could be different if you were using some other tool to TUNE the car, but an OBDII monitor is quite safe.
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Re: Tossed OBDII Code: P0103 (MAF)

Postby ctompkins5 » Mon Jan 03, 2011 10:04 am

I get that on occasion when I have run the car through a jet wash at the gas station. (only in the winter when I just need to get the salt off the car). Anyhow, it is just from getting a bit too much moisture up the intake pipe. That sock on the AEM filter is not water proof, just water resistant. I find if I let it sit and dry just a bit before taking off from the car wash (long enough for me to shammy the car) it usually does not happen.
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Re: Tossed OBDII Code: P0103 (MAF)

Postby stimpyvan » Tue Jan 04, 2011 1:45 pm

I had this happen on my '99 at Pacific Raceways over the summer. The only difference was I would reset on the straight and it would be back on by the end of the lap. Mine turned out to be a pinched harness. Not sure how many G's you were pulling at the time, but mine was triggered by 1.25+ in a right hander (turn 3A). No other circumstances caused the code. Oh, and it was accompanied by a loss of power. I would assume that's the ECU cutting spark to prevent firing during a potentially lean condition (since it has no idea what the current mixture is).

Anyway, if it happens again, it is definitely worth checking the integrity of the harness.
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Re: Tossed OBDII Code: P0103 (MAF)

Postby rpmchris » Tue Jan 04, 2011 3:54 pm

Likely water on the MAF. My CAI is "SCCA Solo legal" and the filter resides right next to the right-side headlight, so no worries about water from road spray. But, mine did throw a code a couple of times when I parked "nose down" and rain drained off the hood, and right next to the filter. I'd start it up, and as soon as I accelerated at anything but a snails pace, it would bog and throw a code. I now park with my nose facing uphill when I think it will rain, and I take it easy when I first start it up, and it hasn't happened since.

Ahhh, the joys of life with a modded car.
'06 MX-5 Sport 6-speed
Autocross junkie!
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