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Legacy 2001 MAF sensor


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13 replies to this topic

#1 Wazzowacho

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Posted 14 March 2013 - 12:13 AM

My vehicle after a long drive recently started cutting out/stalling at idle. It was a very hot day. After much research it seemed to be an electrical problem. The MAF sensor?? However diagnosing the actual faulty sensor is what I'm up against. I watched a video on a guy disconnecting the MAF sensor as his vehicle was also stalling and on disconnecting the sensor the vehicle idled fine. I tried this on the legacy and it didn't idle fine - it stalled immediately.

Any advice would be very welcome.

I will say this that I've naughtily manually increased the accelerator revs so that the vehicle won't stall. I also drove for 6 hours of rough roads yesterday as I needed transport - all with the check engine light on. The vehicle went perfectly without fault.

I did for the record connect the green plugs under the steering and do the manual fault check and count blinks on the check engine icon - there we around 5 faults - 19/21/49/51/53 and 55. Some of which don't exist.
I love my car and any help would be great. Thanks

#2 Legacy777

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Posted 14 March 2013 - 08:14 PM

Welcome to the USMB.

 

If you have a check engine light on, you're on the right track to try and figure out what codes are stored.  I am pretty sure that your car should be OBD2 compliant, and if it is you should be able to read the codes with a standard code reader.  Here in the states, local autoparts stores will read the codes for free.  You could try this and see what codes come up.  I'd then suggest pulling the battery for an hour or so to clear the codes, drive the car and then pull the codes again to see what comes back.  That should eliminate any false or old codes.



#3 johnceggleston

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Posted 14 March 2013 - 09:11 PM

in the US, 00 - 01 (maybe more years) ej25s do not have a MAF, they are MAP only.



#4 Wazzowacho

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Posted 15 March 2013 - 01:30 AM

Hi thanks, unfortunately I'm located in east Africa where Subaru help is limited... The device we plugged in seem to be impressive and obd2 compliant and spat out a little receipt informing us of an error p1141 mass air flow status/ value 0.00.
However to confirm those results is what I'm dealing with... On the one hand the blinking check engine suggests the above faults and then this machine tested MAF to be faulty. Where to from now? Do I take a gamble and replace the MAF sensor believing that to be the cause of stalling engine? It will take a week or so to get the part
down from Kenya and at a cost I would imagine so I understandably am trying to be sure. I did for the record take out the sensor and give it a gentle clean like expressed in other forums and on the web, yet it didn't seem to help. Any further thought would be greatly appreciated!

#5 Fairtax4me

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Posted 16 March 2013 - 08:24 AM

I'm not aware of any way to make the CEL blink the codes on an OBD2 vehicle, so I can't say what those two digit codes mean. Its hard to find info about foreign market vehicles here in the USA.
But with the p1141 displayed, there's a good chance the MAF sensor is bad.
Make sure all of the hoses that connect to the intake tubing are tight and not split or broken. And make sure the intake tubing is not split and it clamped tightly at both ends as well.

#6 Wazzowacho

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Posted 16 March 2013 - 01:12 PM

Thanks, will def take a look at all hosing tomorrow . I guess the question I'm asking is that if the MAF sensor is disconnected at the plug switch should the vehicle behave any differently ? Could it idle correctly should the MAF sensor be faulty and disconnected?

#7 Wazzowacho

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Posted 16 March 2013 - 10:18 PM

Thanks, will def take a look at all hosing tomorrow . I guess the question I'm asking is that if the MAF sensor is disconnected at the plug switch should the vehicle behave any differently ? Could it idle correctly should the MAF sensor be faulty and disconnected?

#8 Fairtax4me

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Posted 17 March 2013 - 01:28 AM

Depends on the type of failure, but yes generally the idle will be different with the MAF sensor unplugged.
With normal operation of the MAF sensor, if the ECU loses the MAF signal (it gets unplugged) while the engine is running the ECU will freak and cause the engine to stall immediately. If the engine does NOT stall immediately upon unplugging the MAF sensor, the ECU is already in a failsafe mode which would indicate that the MAF is bad.
If you unplug the MAF, then start the engine; the engine should run, though idle may be rough. It may lope or hunt for proper idle speed and there will be a noticeable decrease in power if trying to drive.

#9 Wazzowacho

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Posted 17 March 2013 - 01:51 AM

Thanks , re the idle problem I'm having and I have just checked all the pipes and hosing to make sure that all is good and it seems to be!
What else could be the problem when my vehicle which runs beautifully just won't idle and the check engine light glares at me constantly? I've as previously mentioned up'ed the revs manually so that stalling isn't as frequent... It is an automatic vehicle so I'm having to drive engaging neutral often to allow acceleration to prevent stalling.

#10 Wazzowacho

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Posted 17 March 2013 - 01:56 AM

In a previous post by John - in the US, 00 - 01 (maybe more years) ej25s do not have a MAF, they are MAP only.
Excuse my ignorance - my vehicle is an ej25 and is a 2001 legacy - could this sensor actually not be the MAF?
I will google the difference now! As I'm all a little lost over this matter

#11 torxxx

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Posted 17 March 2013 - 03:50 PM

MAP = Mass air pressure.  it measures the barometric pressure of the atomosphere and tells the computer air density.  MAF is mass air flow.  it meters the amount of air coming past a sensor.  

 

Subaru used one or the other but not both from what I remember.  the EJ25D (dohc engine) was a MAF engine, the EJ251 (sohc) is a MAP engine.  The EJ253 went back to MAF for some reason.  

 

If you have an airbox with a square sensor bolted to the airbox its a MAF motor.   If your airbox is bolted directed to the intake and has a filter right there at the throttle body thats a MAP motor



#12 Fairtax4me

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Posted 17 March 2013 - 10:20 PM

MAP: Manifold Absolute Pressure.
It measures and compares atmospheric pressure and intake manifold vacuum and alters a voltage signal based on the amount of difference between the two.

Foreign market vehicles could have had different air metering systems during those time periods. They certainly had plenty of other things that we didnt get here on the US market.

Also some 95-97 cars have both MAF and MAP sensors. My 96 has both.

#13 rick3114

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Posted 05 August 2013 - 08:40 AM

I have a 2000 Subaru outback and have been having brief stalling problems once in a while. When I add fuel injector cleaner, it seems to clear up the problem. I believe the MAP sensor may need to be cleaned, but I can't find it between the air filter and the intake. Where is it? Inside the air filter box perhaps?

#14 Fairtax4me

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Posted 05 August 2013 - 08:49 AM

You can not clean a MAP sensor. There is no element like a MAF sensor has.

You may have a vacuum leak. When was the last tune up? Plugs, wires, filters, PCV valve?




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