anyone know how easy it is, or not???

(Im asking here because there seems to be quite a few folk who work with cars or have owned a scoob)

 

Piece of piss to change, 4 bolts to the airbox, jubilee for the inlet pipe and unplug it

 

cool, think even i could manage that!

 

It's dead easy You might need to remove the battery overnight to reset the ECU though but that's only removing a terminal.

 

thank you.

i thought it was the maf sensor but now im wondering lambda.

Its basically holding back when you put your foot down, juddery.

 

Easy to do...as above... It maybe the lamda... Is there 2 tho on classics like newer blob eye/ bug eye..?

 

After a bit more digging for info i think its the lambda. not sure how many, think only one.

 

If its running rough it'll be the pre-cat lambda, the post cat just provides info to the ecu to tell it if the cat is working or not.

 

It runs sweet as a nut until u drop it down and boot it (overtaking basically), then it hesitates and judders but pulls through.
Its also running heavy on fuel. 100miles (motorway) to £30

 

No exhaust leaks? That can also cause excessive fuel usage.

 

not that i know of

 

inlet hose where it joins to turbo probebly perished at the bottom where oil pools and rots the rubber, one that runs under manifold

 

Sounds more like lambda to me and they are also easy to change, it's in the downpipe and you'll just need a 22mm spanner. The lambda is also gone on mine but luckily I'm on an aftermarket ecu so I've switched it off until I sort out a replacement.

 

just read it again, wont be lambda, wont be inlet hose as once your on full throttle, WOT map takes over on GC8`s and dont use lambda.

i take it cars had plugs recently, if not atleast gapped?

 

serviced and plugs changed last year. due another service really.

mot due in feb so ill have it put on diagnostic.

 

You can read for faults by connecting the the green /black plugs together under the drivers side of the dash near the steering column. the check engine light will flash and give the code. Long flash for 10's and short flash for 1's.

As for the Maf, id change anyway. They are one of the prime causes of melted pistons on Subarus. Their easy to change on post 1998-1999 cars as the sensor is seperate from the housing. Its removed by unscrewing the two torx head screaws and it just pulls out. Around 80 quid from subaru i think. the earlier ones were all one and bolted to the airbox.

As said by others the front lambda is for the ecu/fueling, the rear is just to show failure of the cat. IMO if it was the lambda sensor, it would like be throwing loads of check engine lights as the ecu has various sensors and would show and 'out of range' signal. The MAF sensor on the other hand usually only throws a light when it well and truley knackered. But can cause engine damage long before that happens.

I used to change the MAF sensor every second service on my 2000 impreza.

 

Heres a link which shows you how to read it manually, with pictures. It will also cycle all the cars solenoids so you can check/hear if they are working or not.

http://www.scoobypedia.co.uk/index.p...eadingECUCodes

 

aaarrgghhh maf...lambda.....maf!!!!

thank you.

I know the maf is a common problem on this model.

Will connecteing the green plugs tell me if its the maf??

edited to add that ive found that answer!

 

ill have a go at it tomorrow

 

Or try 2 bolts to remove the sensor from its housing.


Whilst she hasnt stated, her pic shows a classic. They only have one lambda sensor.


No it wont. It would only alert of a total failure. Total failures arent what cause engines to blow up though. Partials failures are and will not throw fault codes.

How about stating what the symptoms are for the problem you think you're having ?

 

Thought i did.

Its running heavy on petrol and hesitates and judders when you out your foot down quickly, overtaking for example. Itll pull through it eventually.

Other than that runs sweet.

whats happens if the maf totally fails?

 

Looking at that, id start with the plugs and make sure they are gapped. Im assuming its using a single coilpack and not the coil on plug setup?

See if that helps. Gap them to 0.7mm, think they come a little wider than that, but thats what I used to gap mine at. And good luck, cause taking them out is a pain in the ass, more so on the passenger side.

I would still recommend changing the MAF if it hasnt had one for a while!

 

yep i remember doing the plugs and theyre a bastard.

tbh it was doing it before that set of plugs and still doing it after (obviously)

 

Will struggle to start and driving will be virtually impossible.

Another good upgrade depending on what year your car is, is to swap the ecu for a 1999 spec. The early 1999 spec ecu AE801 has a much better fueling / boost mapping. The later 1999/2000 AE802 was mapped for better consumption and safety. Mine was a 2000 and had the AE802 and had a lot of flat spots in the rev range. Bought an AE801 and straight swap, and it was like a different car. More BHP too.

 

If totally fails the CEL light will come on and car go into limp mode which should be relatively safe.

As it's failing, with no warning the car can run lean under load which will result in a blown engine.
Wouldnt say it would generally make it heavy on petrol though.

A malfunctioning lambda sensor would generally cause high fuel consumption, but will have no impact on performance under load. Idle, part throttle maybe, but not full load.
And again, this will not throw a fault code.

If the car has never had a MAF or you dont know it's history, you would be doing no wrong by replacing it.

 

It will still start and drive with the MAF unplugged. Same as with a totally failed MAF.

 

If your happy the plugs are gapped ok, (and it could be that the last set were not gapped properly either, it only takes a small amount to cause a misfire), then try the manual code reading, just to see if theres anything sensor problems.

Stick a question up on scoobynet for advice, its been 4-5 years since I had my impreza, you will get some helpful peeps that may be in your area

 

Think im getting my wires crossed now If they are working the car should cut out when unplugged. if knackered it will just run on ??

 

Modern cars have many limp home strategies in the event of component failure to get you home.

The car will start and run without the MAF plugged in. It will of course not drive as normal, but it will drive.

 

thanks guys. lots of useful info there.

ive put a post up on scoobynet but tbh theres been more info on here. one guy has said his was doing the same and it was lambda.

chrisa-its a 1999 so could be either ecu

 

Ellie have you tried cleaning the old MAF with a cotton bud and some brake disk cleaner, sometimes these thing get covered in crap and might need a clean.

Its a cheap and easy.

 

when my 99 scooby did this a new coil pack sorted it

 

If your planning on keeping the car long term, it would be worth investing in a diagnostic cable. The regular VW OBD2 cable from Gendan for around £25 is compatible with subarus from 1998 onwards. You can download for free a copy of ECUExplorer which is an open source subaru diagnostic software.
EcuExploer displays realtime sensor information and fault codes, allows you to clear codes and reset ecu on the fly.

Its also easier to diagnose problems with lambdas and MAF sensors etc as you can see the voltage outputs from the sensors in real time. It also displays the maximum and minimum readings since starting the software. Once upto temp the lambda should see a peak voltage of around 5v and a minimum value of around 0.1v.

Its a good piece of kit to have, especially with Subarus, diagnosing issues with them is just a nightmare and can be expensive if your having to take it to a garage.

 

Best bit of info yet!

 

Except the lambda sensor on a Subaru is narrowband and gives the same 0-1v output as every other narrowband sensor.

 

Yes i stand corrected, its max value will read 1v

 

The only problem with inexperienced people reading these scanners is often they misinterpret stuff

Just because for example the lambda sensor may indicate rich ( ie higher voltage ) certainly doesnt mean the lambda sensor is at fault.
The only correct way to test a lambda sensor is with an oscilloscope to see how fast it's responding.

 

If you haven't changed the maf since owning it I'd say it's the maf. There really poor on the my99-00.
Induction kits will kill them even quicker.

 

oh i dont know what to do!!!!!

Ive had the car 2years and not replaced the maf.

If i just take it in somewhere for a diagnostic will they be able to tell whats at fault?

 

Yes. Maf's are around £90 quid for a new genuine part.
But you'd be better off getting it plugged into see the fault first.