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How do you know when your MAF is dead?

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Old 11 March 2005 | 02:22 PM
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From: Over 500ft/lbs of torque @ just 1.1bar
Question How do you know when your MAF is dead?

On the fragile MY99/00?

Mines done around 60k miles. Is unable to boost anything above 0.9bar without significant KL activity (still has some amber activity @0.9bar). Std AE800 ecu. It had been in the same state of tune for over 2 years and never missed a beat...put a KL on it was lighting up like a Christmas tree.

Should I just change the MAF and see what happens?
or could it be something like spark-plugs and coil-packs?

Your views appreciated.
Old 11 March 2005 | 02:56 PM
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Bob,
You will find your car will be hunting for idle with a failed maff.
Old 11 March 2005 | 03:12 PM
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no probs with idle.
Old 11 March 2005 | 03:16 PM
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can be lean without failing. Know anyone with deltadash ?

I have a 'spare' maf you can try if you want. (pm me if reqd)

Steve
Old 11 March 2005 | 03:24 PM
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From: Over 500ft/lbs of torque @ just 1.1bar
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Originally Posted by stevem2k
can be lean without failing. Know anyone with deltadash ?

I have a 'spare' maf you can try if you want. (pm me if reqd)

Steve

I have a secs data monitor but havent really used it yet.

Thanks for the offer for the MAF but I will likely replace it as a matter of service anyway.

Just trying to establish what is causing the KL to light up with such low boost.

I think the SECS does AFR so I might plug it in and have a look.

Bob
Old 11 March 2005 | 03:32 PM
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Just had to change mine. It only hunted when cold then was fine. Did an ECU reset and up came the error codes for MAF sensor. Also noticed on my Blitz R-Vit the AFR was all over the place when accelerating now it is steady on 0% under acceleration, I presume this is how it should be?

Also if you do change it just get the sensor, should be about £85 from Subaru.
Old 11 March 2005 | 03:44 PM
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Originally Posted by sillysi
Just had to change mine. It only hunted when cold then was fine. Did an ECU reset and up came the error codes for MAF sensor. Also noticed on my Blitz R-Vit the AFR was all over the place when accelerating now it is steady on 0% under acceleration, I presume this is how it should be?

Also if you do change it just get the sensor, should be about £85 from Subaru.
Could you describe this 'hunting' when cold?

How did you read your error codes?

Bob
Old 11 March 2005 | 03:56 PM
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When cold she idled OK until I slowed for say a junction, when I pressed the clutch down the revs dropped almost to stall then picked up. After 5 mins or so she idled fine.

I had it checked on a Subaru Select thingy but there was a recent thread giving the details from I think the MRT website? This showed the sequence of CEL flashes after a reset which indicated MAF problems.

Last edited by sillysi; 11 March 2005 at 04:17 PM.
Old 11 March 2005 | 03:58 PM
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From: Over 500ft/lbs of torque @ just 1.1bar
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Originally Posted by sillysi
When cold she idled OK until I slowed for say a junction, when I pressed the clutch down the revs dropped almost to stall then picked up. After 5 mins or so she idled fine.

I had it checked on a Subaru Select thingy but there was a recent thread giving the details from I think the MTR website. This showed the sequence of CEL flashes after a reset which indicated MAF problems.
So if after a ECU reset there is no CEL flashes....all is clear?

Bob
Old 11 March 2005 | 04:07 PM
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I gather it may take a few resets of the ECU to get a CEL if there is a problem, it did with mine.

http://www.saxonfields.freeserve.co....iag%20Page.htm

Last edited by sillysi; 11 March 2005 at 04:18 PM.
Old 11 March 2005 | 04:53 PM
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My MY99 had no discernable problems at all (It really did drive perfectly) until I swapped the ECU for a PPP one. Then every time I came off the throttle to pull up at a junction etc. the revs would drop to 400/500RPM before recovering. New MAF sorted the problem instantly... I don't know how long my MAF was dead/failing for before, but I will change it reguarly from now on...
Old 11 March 2005 | 05:10 PM
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In my MY99 STiV the idle was perfect, but the hesitation and lumpiness in most gears around 4K rpm gradually got worse over a period of weeks. O2 sensor was changed at first (as idle was good) but no difference - a change of MAF sorted the problem.

Incidentally, an ECU reset prior to the new MAF temporarily solved the problem and car went *really* fast!
Old 11 March 2005 | 05:43 PM
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From: Over 500ft/lbs of torque @ just 1.1bar
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Just been out in the car with secs running. No fault codes. Reset ecu anyway.

Not getting any knock correct as far I could see either...(one eye on the road). WIll take somebody out later in the car and get them to keep an eye on it.

Peak boost was 0.95bar.

Bob
Old 11 March 2005 | 05:53 PM
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When I suspected that mine was failing I took it to a dealer and they offered to put a new one in to see if it made any difference. It did so in it stayed.

It's a 2 minute job mate - go smile sweetly at your local Subaru shop.
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