grahamdance

I've read through some of the previous MAF threads on here with increasing dread, I think mine is fubared:

Occasional lumpy idle
Occasionally juddery on boost
Slightly increased MPG

Sound about right?

Will try and read the fault codes this week, I understand its easy to change, how much will it lighten my wallet?

ozzy

Sounds right. Cost will depend on which model of car you have. If you search you'll find part codes, cost (approx £70 for a MY99/00 car) and fitting instructions.

dowser

Make sure new one has the green dot on it, and reset the ecu after fitting. If you're really unlucky, the ECU reset will highlight a knackered lambda sensor too. If you're really. really unlucky you may suffer a bad idle even after changing lambda and MAF. If so, strip and clean idle stepper motor (on top of throttle body, 2 x-head screws and it comes out).

Richard

grahamdance

Its a '99 turbo wagon, as you can see I'm a newbie so I dont understand this "MY" stuff!

Will take it easy until I can get hold of another unit.....thanks for your help people

ozzy

MY=Model/Year. £70 for a 99 UK wagon. Any new bought from a Dealer should have a green dot on it. That's the more resilliant one.

grahamdance

Fantastic, thanks ozzy.

I went out in the car today, felt like there was very little boost, sounded like the wastegate was permanently open. Would this be related to a faulty MAF sensor?

ozzy

Usually if the MAF is misbehaving it'll hesitate badly accelerating. If it fails completely it should throw a CEL (Check Engine Light) and go into Limp-home mode. That restricts boost and would feel VERY slow.

TimWRX01

iTrader: (1)

My CEL has come on and I have taken my MY01 bugeye WRX into a garage. they don't know whether it's the lambda sensor or not. What is a MAF?
The car idles really badly and although it's still driveable it doesn't feel as good as it should do.
I've only had it just over a week though and because they are paying for the parts they won't replace the lambda until they know it's definitely that. They are trying to get another car and use the parts of that to check!

ozzy

MAF - Mass Air Flow sensor

Both can show symptoms of hunting on idle. The CEL should tell them which sensor has thrown up the error. If both, then it's possible both are needing replacing.

The Lambda would be easy to diagnose if they have the right equipment. Tell them to replace both and they can worry about the costs themselves.

TimWRX01

iTrader: (1)

They won't replace both. They reckon the lambda will cost £250 and the MAF £300 so they want to find out which one it is. Considering I only had the car 3 days before the CEL came on it's a joke.

Andy.F

On the 01 WRX

Unplug the maf and reset the ecu, if it runs sweet it's the maf at fault. If still rough, unplug the O2 sensor and do the same test, if it runs fine then its the O2 sensor at fault.

Note - both these actions will cause a CEL but it will reset when plugged back in.

Andy

TimWRX01

iTrader: (1)

Cheers Mate! How come they don't know this at the garage though? I've already had it in twice and am still driving round like a prat with the CEL glaring at me.

grahamdance

I've just tried to get the fault codes, but I can't find the male black connector - both of the 2-pin green ones are there, as well as the female black one. Not my day today!

No sign of a CEL either - but this could mean the MAF is faulty, rather than completely failed?

Mark_S

Those prices dont sound right, MAF cartridges (classic or new age) can be had for <<£100.

5tuart

Where can I buy a MAF for less than £100, I looked on the net and couldn't find one anywhere?

I'm up in Aberdeen and scoobies are 10 a penny, you would think it'd be easy to find on at a decent price.

Scooby555Chris

sorry to come in late and ask questions..

my98....i did the bottom end over 7 months ago...bearing spun...etc

runs ok..or so i think it does...did the maf problem ever affect earlier models..

and when the maf really dies and its driven it can kill the lump can it not?

cheers in advance..

ozzy

A MAF fault can affect any car regardless of age. It's just that on the MY99/00 cars the MAF has been shown to be a little delicate and prone to failing.

If a car was driven hard with a faulty MAF, then it can cause serious damage. If it were faulty and the car was driven very gently (i.e. not put under any load) then it should be fine.

ozzy

It depends on the model and year of car. Any MY99/00 cars use MAF part no. 22794AA010 (CP Airflow) and cost about £75 from ANY SUBARU DEALER.

With earlier cars the MAF comes with a new bit of air hosing and costs around £300. No idea about the later cars. What you need to ask is whether the part is just the MAF sensor itself (should be cheap'ish for any car) or is supplied with a whole lot of other plastic cr@p you may not need.