I've noticed in the last few days that in 4th and 5th the boost seems a little unsteady. I've not noticed it so much on the gauge but rather in my back. Its particularly bad at high speed, high load on WOT (i.e 120mph at still accelerating).

The idle is solid as a rock but I'm led to believe this shudder could be first sign of a dying MAF. How can I check this? Will an error code be showing up or will the ECU have no clue that the sensor is on the way out?

Could it be the Lamda sensor? Over the 3 weeks I was on holiday I was running 1/2 a bottle of NF per tank (it was hot!) and I once heard that booster can coat the lamda sensor!

Any advice welcome, especially if its before the engine blows up

 

Had a similar experience (although not at thoses speeds )when my Maf was on its way out.
I used to get a shudder / loss of power at various rev ranges, but the idle was bang on. CEL never showed anything.
I borrowed a mates spare sensor for the day and the difference was instant - bought a new MAF (£60 + Vat) the day after.
Chris.
P.s. I've heard some "good" dealers will let you try b4 you buy- just to make sure thats whats causing the problem.

 

I first noticed it at 70ish but needed to 'test' - as expected it was worse at those higher speeds

 

Mine use to do it around 4 K revs then again at 5k.
Its a weird feeling and hard to describe, but it was down to the ECU thinking there was less air flowing over the sensor than actually was flowing, and therefore cutting the amount of fuel being injected.
Hope you get it sorted.
Chris

 

thats a lot of booster!

 

Any other opinions/thoughts?

 

Do the fabled ECU reset. It will then forget how to compensate for the MAF problem (if there is one) and it will stop idling correctly etc. Did on mine anyway!!! I had the same symptoms as you!


Andy

 

Oh, good thinking - I'll have the car in Nobles to get the sidelight repaired soon (tw@t in car park!!) so I could get them to reset it

 

Fuel Surge? (well it had to be said ).

Seriously, how old is it? If it's the original then it's quite likely it's time is up. Have you had it on DeltaDash/Select Monitor to see if it's reading correctly?

If in doubt, best to replace it!

Good luck,

Matt

 

The car was an early T-plate so that's about 90 in MAF years I'll have the dealer reset it and offer an opinion after that. I might see if I can get them to do a quick swap (assuming its possible to quickly swap it!)

 

It is

 

How to reset the ECU yourself
Try the above - may save you a trip to the dealers.

Chris

 

Where do you get the special allen-type keys to unscrew the MAF from its housing.

Simon

 

Simon,
There called Tarox screws.
You need a Tarox bit to remove them. Most hardware shops sell single ones or a full set for around £5 - £10.
Maplins were selling sets for around £5 a few weeks ago.

Chris

 

Mikey

 

Torx screws ST, except these are the security type of torx screws on the MAF i.e. they have that little nipple type thing on them, you can either buy the security type or just snap the little nipple off with a screwdriver and use the normal type

 

I stand corrected

 

Simon

 

Hi
Im begining to wonder if my MAF is dying too(ouch), I reset my ECU and the car would idle badly and cutout at junctions etc(is ok now though).
I also have an AFR meter which Im having trouble interpreting the results, when i rev car and let off throttle (idle) the meter reads rich (green) for a few seconds and then goes back to the disco situation (up and down), when on full boost WOT it doesnt appear to read anything but goes green again when u let off for a few seconds. Also when off boost cruising at 70 ish it doesnt read at all, when I first start car from cold it reads OK (yellow) for about a minute I guess this is as the sensor (lambda) warms up and is closed loop?

any help would be greatfully recieved as i dont want to blow my engine up, its the first scoob ive had (MY00 turbo) and i was toying with buying a MAF anyway just to be sure but could it also be the LAMBDA as I know they wear out pretty often.

Many Thanks
Cheese......

 

AFR should be green under WOT then go discotastic in between and as you have a MY00 I would expect 'green to amber' at idle with nothing appearing only when you lift off.

Off-boost is a bit irrelevant here but if you have your foot on the accelarator then I would expect to see lights

I would get yours checked out cheesy puff ASAP

Cheers
Si

 

Thanks for the help I think a trip to shop for a MAF tomorro morning, could also be lambda sensor itself as it looks kinda original. Will buy MAF anyways as a precaution as its bound to go sometime, funny thing is I fitted the AFR meter after trauling for info so i fetted it right and then figured out that I dont actually know what sort of readings to expect. Doh

Thanks
Cheese....

 

Im back LOL

right ive just been to my localish dealer in sevenoaks in kent and they dont have a MAF sensor in stock and say that there is no problem with MAFs on these models (my99-00) that they know of and have never sold one hence why no stock, now the man i spoke to was helpfull and did check my idle etc and said was perfect and had seen far worse. He said th MAF will either break or be ok (no deterioration) but from what i can make out on here thats not the case and while i dont have money to chuck about 70 quid to save engine sounds ok to me.
Is there anywhere i can order online?
As i said before when u rev the engine the AFR goes into green but will not hold this setting under WOT could it be the Lambda is at fault? eitherway ill buy both to be sure but now it would seem im having problems getting them to let me have one lol.

Any thoughts anyone...

Cheese....

 

CP,

The MAF on the MY99-00 is the weakest in the whole model range and are very well known for being very fragile. A friend of mine had 3 in 18 months and 5000 miles on his MY00. It may well be that your MAF is fine but unless it has been checked and found to be fine, I would suspect it. Lancasters (I assume it's them as they are the only Subaru dealer in Sevenoaks I think) are frankly wrong - plenty of people have had MAF failures on here which were not all or nothing. Often, the sensor starts by reading just a little lean but will otherwise appear to be working fine. This can lead to a total engine failure if left long enough. I would consult a different dealer if I were you!

Good luck,

Matt

 

Hi Matt

Yes you guessed the dealer and they were helpfull but as I suspected totally wrong, its just the fact that I dont get consistant readings from the AFR meter that worries me and that when i reset ECU it runs badly (but ive been led to believe that even a new MAF may do this at first after a reset)for a while.
Could be a faulty Lambda I suppose?

Many thanks for your help and does anyone know of a better dealer in my area? (bexleyheath)

Cheers

Cheesy....

 

I have a Dawes AFR meter on my MY99 and got the same symtom. First 2 or 3 times I do a WOT, reading from AFR is OK ( Green) then the lamda heat up and gradely the reading go lean. When car is hot I can only get yellow reading. I'm sure this is normal and it's only the Lamda that heat up and give wrong reading. Remember the ECU only use the lamda up to around 3000rpm thaen it change to adjust AFR based on MAF etc.
My car has done this since it was new and it has now done 100.000 km sorry around 60K miles and still going fine
Lars

 

i've had similar symptoms went to main dealer to be checked they said it was maf even thogh no fault codes showing ordered a new one £186.00+vat ouch! my94 wrx wagon (why are later ones so cheap? perhaps that's why they go wrong more often)

Matt