[666S]

For reference:

P0103 - Mass Air Flow (MAF) Circuit High Input

Relevant Mods:

CP-E 3" cat-back
CP-E 3" CAI
HKS SSQV BOV
GReddy PRofec B-Spec II EBC

Story:

Ambients around 50 F, rain, night. EBC set to 39% / 13# gain, usually good for around 16.5 - 17# boost. Pulling hard away from a light, ran the engine up to about 6200 in 2nd gear. I hit fuel cut, which has happened several times, but it seemed to cut especially hard and threw the CEL, no flash. Immediately backed down to granny-mode driving and pulled off, killed the engine for about 2 minutes, refired. CEL persisted. Rinse and repeat, still it's on.

It's not flashing so I'm thinking it's ok to drive, took it about 20 - 25 miles to a friend's house and parked it for about an hour. Drove for about 2 miles, all low-speed residential neighborhood, light stays on. Parked for about an hour and a half, refired the engine, and the light was off.

Got my scan tool today and had 1 stored code, P0103 (link above). Code describes a MAF sensor high voltage. My limited experience with sensors is that they use very clever materials that generate signal voltages based on conditions, then a computer interprets those voltages (or currents, depends on the sensor) and compares against a pre-set calibration to derive values describing the conditions observed by the sensor. I suspect that the EBC running boost above the stock boost levels at high rev caused more air to be coming through the intake than the car expected. It's still trying to control boost via the stock WG solenoid, but it's disconnected, so there's a mismatch between the manifold air pressure observed and the amount of air transversing the MAF sensor. ECU says "where the hell is all this air going??" and throws the code.

I cleared the code (RPM ScanGauge II GB FTW) and expect no further problems (unless I drive like a jackass again).

Comments? Has anyone else specifically seen P0103? This is a generic OBDII code and should apply to all OBDII vehicles, not just turbos or the MS6 in particular.

 

[ryceboi]

while you are the first to get a P0103, another member has gotten a P2187 - system too lean at idle, while driving in the rain as well. while most people will agree that you will not waterlock your engine unless you drive through a lake, it is very possible that water or moisture can soak into or move through the filter and short the MAF sensor or cause the readings to go haywire. i suggest the next time you drive in the rain, whether you get this code or not, remove the filter after you're done driving and touch the inside of the cai pipe. if there is moisture, then maybe it's time to invest in a hydroshield.

 

[666S]

Thanks for the input. I'm not much inclined to suspect rain as the culprit, but obviously neither you nor I has much data either way. I've driven the car in much worse rain than what we got here in Northeastern Ohio last night with no issue.

Do you mean to say that CAI owners have had CELs just from rain?

 

[yomama69]

Thanks for the input. I'm not much inclined to suspect rain as the culprit, but obviously neither you nor I has much data either way. I've driven the car in much worse ran than what we got here in Northeastern Ohio last night with no issue.

[/b]

Lucky for you it was just rain. We're just a bit North of you and got almost 2 inches of snow dropped on us in less than 2 hours.

 

[PerfectXtreme]

He Means that water is bad for electric parts.. and the engine.. and CAI provides a much easier entrance for the water than stock intakes... I've driven through rain and such with no problems...

HOWEVER in high humidity or some heavy puddle driving... enough water could have splashed up onto the filter and been sucked in...

I need to get myself a scantool here pretty soon....

 

[666S]

This was a divided state highway though, definitely no puddles.

The ScanGauge II is nice for reading the codes, but the manual that comes with it is a little sparse. Fortunately most of it can be figured out with a little thought and focused guesswork (FWT?! WTF is an FWT sensor?? Oh, "water temperature" in Fahrenheit. Gotcha. Stuff like that).

Anyway I'm not worried about this code. It hasn't come back despite driving home in similar rain, and the few others I've found online with this code (a few of them from Mazdas, several not) nearly all say they cleared the code and it never came back.

Ah yeah, here's another interesting link:

P0103 specifically

"A more technical description would be that the MAF circuit had higher than expected voltage (air flow)."

That would be consistent with what I guessed originally, that there's more air passing the sensor than the ECU expects based on how it's trying to manage the WG. Of course it *can't* manage the WG and that's why there's more air than expected.

I'm satisfied.

 

[msumlin]

Call Shawn @ Park and have him give you more technical information. I am sure he will give you solutions as well.

 

[666S]

Call Shawn @ Park and have him give you more technical information. I am sure he will give you solutions as well.
[/b]

I may, if I'm bored enough this afternoon. At the moment, though, I feel as though it's no longer an issue. Any investigation at this point would be simply to satiate my own curiosity and provide no impact at all on a future course of action (unless, of course, the code returns, but I'll bet your tab tomorrow that it doesn't ).