torment

Can any of you guys please tell me how to tell a maf sensor`s failing please...?.

Mark_S

For me the car was behaving erratically. Strong acceleration followed by hesitation in 4000-5000 rpm range, no problems on tickover though. Finally got CEL which I'd never had before. MAF was changed this weekend and all is well again. If in doubt change it, the part was only £73 incl VAT and dealer didnt charge for fitting (its a 10 min job max).

nom

If 'symptoms' are a bit vague, reset the ECU (a search can show you how to do that - or just disconnect the battery overnight). The ECU can learn how to get round dodgy MAF output (eg at idle) hence the problem doesn't show up until it's really bad.
What MY do you have? Makes quite a difference!

torment

Thanks guys its a MY 1995 Sti,It had a irregular tickover whilst getting warm,I removed the maf and gently cleaned the fragile wire with petrol and the compressor parafin gun,Then blew dry,And it ran ok afterwards,But to date not yet tried it again cold.....?.

erinyes

MAF's are 73 quid :O i thought these were 400 pounds odd?!?!?! i have a similar problem, fine on idle, but eractic performance, one day rocket ike, next day feels like im being held back almost. no CEL though...........is the '94 UK MAF the same as a '93 WRX?

nom

Should be OK at that MY, or at least it's not a 'known' dodgy sensor...
There are a fair few things that can cause a bad idle. Idler's a good thing to clean too - can get gunked up over time. I'm afriad I'm not too sure where it is on your manifold, though

Mark_S

James, the complete part including housing is 300 quid or so but the cartridge alone is as I mentioned only £73.51. The part no. for my car (MY00) is 22794AA010. Do a search on MAF's to see if this part no. is correct for you're model year I cant advise on this. But if you dont want a damaged engine I would suggest you sort it asap.

stanmo

iTrader: (1)

Error code 23 ?

Mine failed after 3 years, to an unmodded car; no symptoms of erratic idling. PSI Secs monitor did record an error 23 though.

I'm going to get it changed every 2 years from now on just in case.

akshay67

Be VERY VERY careful.

What year is your car? The MY99 MAFs are rubbish and Subaru did a recall on them in the USA.

My MAF was failing and I couldn't tell until I did an ECU reset. The problem is that slowly failing MAF symptoms are corrected by the learning-ECU and therefore are not noticeable.

Your car may also feel as though its getting faster and this will be because it's running lean...leaner...leaner...BANG!

drb5

iTrader: (4)

how do i clean the idler?

Cheesy Puff

Hi

Im very worrie aout the MAF on my MY00 Turbo as im getting the hesitaton beween 4-5000 rpm mentioned before, my AFR meter is also not reading any constant readings except when i lift off after booting it then i returns to the up and down disco thing.

What really concerns me is that I have been to two dealers who both have denied a problem and have both said MAFs just work or dont work and dont have anything inbetween, alsoIve tried to buy a MAF just incase and am almost getting refused the sale of one.

I am now in the position of having to phone my local dealer to and have to convince them to sell me one, Ive also asked the same question on the SIDC Forums and get conflicting arguements aswell.

What should I do im only trying to save myself a blown engine in the long run.

Help me please

Cheese....

akshay67

Cheese,

Do an ECU reset and see what happens to the idling soon after starting the car.

Stand behind the exhaust and see if the cylce drops in power at the end of cylce.

Then, stop the car, disconnect MAF, and start car and observe idling - is it any better?

The all or nothing MAF failure is non-sense, as I know from first hand last week. Its the MY99/00 ECU's that mask the problem.

My advice would be spend £70 on the new MAFs that Subaru have produced to replace the crappy ones (they did a recall in the USA - says it all), that way you can rest assured (although doesn't make you immune to MAF failure).

Cheesy Puff

Cheers for the help as this is driving me bonkers, when I reset the ECU the car runs like a bag bolts until the ECU relearns.

What I cant seem to get any clear answer on is wheather that is normal even with a perfectly functioning MAF?, My AFR meter will read a constant slightly rich indication when you let off the throttle but not when actualy on the gas so to speak then it drops back to the up and down again.

some times when driving it can go off alltogether then come back on up and down again.

Why are the dealers so ignorant/in denial of the problem and why is it like pulling teeth to get them to take my money.

Cheers
Cheese...

akshay67

after the ECU reset, disconnect the MAF and how does the idle sound?

perhaps you should stick a new MAF in and see if its any different (either buy or borrow one)

Cheesy Puff

Thanks for your help Ive actually ordered one now to collect at the weekend (could of had sooner if they had listened to me before), more or less had to convince the salesman that I was correct and that they do go "iffy".
If my old ones ok Ill keep as a spare as they sound a bit fragile anyway, heard you can tell if its a new or old one by the number of pins in the plug the new ones have a pin missing.
My car has all the pins so assume its an old type and as my car has done 106,000 miles probably due a change anyway, I may even treat her to a new Lambda sensor too (Halford £25 jobbie).

Thanks for all you help, this is the first scoob ive had so taking a bit of time to get used to the bits and bobs of it all (im used to citroen 16valve lumps and knew them inside out).

Cheers
Cheese.......

parso_rex

Cheesy puff,
Mine just recently passed away. Symptoms in my case were very rich idle you could actually smell & see it (thought it was time to get the unichip retuned to suit a few additions). We then had club dyno day which showed the AFR around 13:1 at full noise i.e not good at all and obviously the AFM. Two days later after not running full boost in preparation for its replacement it completley died and would not idle. In this case if you are stuck you have to disconnect the AFM to restore a usable idle and limp home.
I was lucky as I'd been running 1.2 bar at the time and only the dyno's AFR meter showed up the true problem up top.
Your is a 95 model aren't they the hot wire type as against the hot film crap one ? might be different altogether
Regards

Mark
Aus........

Franko

Akshay67

If you disconnect the MAF does the engine not stall?
On my Sti MY98 the engine stalls.. maybe diferent ecu or sumat?

akshay67

disconnect maf when engine is off! then start engine - no problems on my uk99. i did disconnet it when the car was running and it wasn;t happy!

cheese,
make sure you inspect the MAF to make sure it is a newer one. You existing one has 5 pins. new one has four.

new one also has some white numbers printed on it. I took my old MAF with me and compared the two. Also, if you can get a good angle in the light you will see that the metal film is different too - it seems like a solid chunk on the new ones and one the old ones there is a big gap in the middle...well mine did anyway!

messiah

new MAF on order from dealer to collect next week. Will take battery off overnight to clear ECU also - is there anything to be aware of when doing this? just curious cos on previous cars when disconnecting battery, the alarm would sound (a lot) when it was reconnected.

Should I deactivate alarm prior ro disconnecting battery?

wigan wayne

Hi lads
Just to jump on your thread, I have a problem that could be related to yours.

Parso rex you speak of over fueling on tickover, smell etc.
Well I'm am experiencing a knd of miss on tickover light throttle, could
overfuelling 'drown' the plugs as when she gets going she flies and
only experience slight hesitation sometimes.

Would the failing maff think there is to much are therfore put more fuel in?
then as I accelerate 'use' up the fuel?

Any ideas?

cheers

WW

jonmyers

Sorry to barge in on this thread...

Had problems recently similar to those described above on my MY99 and a new MAF (the new 4 pin variety) has cured the erratic idling and hesitation.

However, I never reset the ecu after replacing the MAF. Driven some 1,000 miles since but should I reset now?

Thanks, Jon


[Edited by jonmyers - 11/13/2003 2:47:15 PM]

akshay67

the 99 ecu is of the learning type, so it should have learnt anyway...

Franko

If i disconect the MAF and then start the car it wont start.. think its to do with the ecu as its an import

I have problem of losing power at 4k revs n above car just seems to stay at the power its at and not go much stronger whereas it would pull like crazy before. MAF arrives on tuesday so i'll see if it makes a difference

Dark Blue Mark

Would be interested in the restult Franko. My STi 4 has an idle problem and replacing both the MAF and Lambda didn't fix it.

MB

Franko

Will be posting up my finding mate
I hope it does cure it...

have you tried reseting your ecu?

torment

Looks like the MAF is integral with its housing,i have been quoted £250+vat for one on my 1995 wrx sti(Hell fire...i said i did`nt want the exhaust system with the maf)I know the later ones,You can just buy the maf without the housing(and half the engine)So you can get yours for a fraction i can.....(S..t)..Kev.

Dark Blue Mark

Franko,

No, not yet, but I will give it a try.

MB

Cheesy Puff

Well after all the problems I had Ive finally replaced my MAF with a new one and its like owning a new car, My AFR meter now actually shows a consistant reading when revving the engine before it would just read nothing as you booted it.
This does prove that you should be very wary of that sensor as my car idled perfectly at all times, also two dealers told me the car was fine but I think I have saved myself a blown engine.

Only thing is ive been driving it like this for about 3 months what damage could i have done, luckily ive only been going to/from work (2 miles) and not canning it because of the suspicion that the MAF was iffy.

Goes to show that the knowledge of the enthusiast owners is more valuable than the dealers, first time that ive almost had to force money in their hands to sell me a part.

Cheese.......

gravelexpress

db Mark,
tell me how you get on. I am looking at buying a STI 4 and it has idle problems like yours see my thread.

Dark Blue Mark

Will do. Saw the thread but can't comment as yet.

MB