Alberick

Since the garage where I bought my 99 Turbo back then closed itsdoors, I went to a quite renowned Subaru specialist (also an official ECUTEK dealer) and I was told that the MAF should be replaced as part of the regular maintenance schedule. I was told that the MAF should be replaced every 60000 km just to be "on the safe side". Is that true, since this is not what the manual says and also none of the numerous Impreza magazines I have from Japan.

I remember I had a MAF failure when the car had about 10000 km and it was replaced under warranty. The car has 90000 km now and I did not change it since then.

Ramon

pslewis

This will open a can of worms ...................

From what I have worked out, I have a MY00, the MAF tends to go if you foook about with the induction ........... leave well alone and it seems to be absolutely fine (although, as you would expect, you will get the odd failure to standard cars).

Its one of those 'scare stories' that get thrown up ................ like if you don't disconnect your camshaft sensor after an Oil change the Engine number 3 cylinder will let go! Yes, its true - some people swear by it!!

Change it if it makes you sleep safe at night, certainly I am enough in tune with my car to know when something is different or wrong (and I'll deal with it then) .... of course, you'll get those that say that the MAF Fault 'gradually' happens so it kind of 'sneaks' up on you and destroys your engine!! Make your own mind up!

Pete

Houghton

iTrader: (1)

The MAF Fault 'gradually' happens so it kind of 'sneaks' up on you and destroys your engine!!

Do a search on here to get others opinions but the MAF does seem less robust on MYs 99 & 2000 as you experienced 80000 km ago

Oh and disconnect your crank sensor after an oil change too

Bob Rawle

Pete you are on very dangerous ground, in ridiculing the oil change procedure we all had a laugh, this is not anything to take lightly and WHATEVER induction you have the original mafs fitted to cars between MY99 ans MY00 inclusive "fade" over time producing gradual lean running with due increase in cylinder temps and egt's. So if you have an original and its been on the car for 40k miles then I suggest that the only "**** behaviour" would be to leave it in place, otherwise those behaving sensibly would be well advised to change it.

Just my view based on my limited findings from remapping the b***dy things and the number of times I had to return to base to replace the maf for this reason. Treating it as a 40k servicable item is eminently sensible.

I do however join you in admonishing the "its yer maf mate" brigade who use it as a whipping post for any ill.

BTW as it gradually leans out the car will appear to improve in performance !!

all the best

bob

pslewis

Strange that, with LESS fuel you get better performance????

You wouldn't be applying the **** rule book to the laws of physics, would you now??

I am assuming that you mean the mpg improves, not the performance?? My 38mpg would indicate a lean running engine then? Or a light right boot?

This MAF thing makes me chuckle ........ it gradually drifts out of tolerance .... the ECU would then react by substituting a 'safe' value and illuminating the CEL!! ............... but, no!! the ***** come back with the comment that the ECU cannot detect the MAF value as false - come on!!

As I said ...... replace it and join the groupies if you feel safer.

I have a MY00, 58,500miles, original MAF, un-mapped ECU, and original brake pads ............... and I don't scare easy!!

Pete

ps. I would LOVE someone to actually explain how the MAF 'fades' over time?? How does it happen?? Why does it happen??

P.S leWiS

**** loves all, dad how are you?

ex-webby

Pete,

The leaner the mixture (as regards to getting closer to det & all things being equal), the better the power regarding better combustion. To map a car to it's utmost effectiveness and efficiently, you would map a car to actual det and then retard. At the point just before det or on the verge of det (with everything else being equal) the car will be at it's most efficient combustion wise. This of course would be even more evident in standard cars ..... these run as rich as you like, so running lean on fuel would release some performance.

Is that **** enough for you!!??

Regards,
Shaun.

pslewis

Thats a PERFECT **** answer, actually .... and illustrates my point rather well.

You use the words, all else being equal, which of course - never is. You are talking theory rather than practise.

We have all experienced the feeling of more power just before the engine runs out of fuel ........ but that is for a few seconds of power surge.

I firmly believe that if you don't **** about with the Induction then you will be fine with the original MAF Sensor .................. how many people are out there running Imprezas from MY99 and MY00, not a member of SN, blissfully unaware of the scare stories and perfectly happy??

We MUST stop scaring people!

Pete

ex-webby

Pete,

**** or not by your interpretation, I have seen with my own eyes that just taking fuel out of a map increases power. You have to use caveats to stop people from taking what you say literally in all cases. It's not always that black and white.

Regards,
Shaun.

pslewis

In that case, I am amazed that Subaru - with its reputation for heavy fuel consumption - wouldn't jump on that map and instal it immediately. It would make the owners happy, less fuel in exchange for more power .................. I wonder why Subaru have missed that one then with their $Billion research funds??

Confusing?? But then again, the petrolheads on here probably know MUCH more than Subaru does about Subaru Cars??

I am honoured to be amongst such emminent *****

You cannot beat the fact that Subaru WOULD have done it had it been the best thing to do.

Pete

dj219957

Surely,
Subaru, in fact all OEMs run a rich map becuase its far safer to run a rich map than a lean map which is allways on "the edge". Specially since not all cars will run exsactly the same from the box. Yeh... your real "in tune" with your car. You dont even know where the dip stick is.

ex-webby

Pete,
Remember tolerances on cars and setups from the factory differ, that coupled with varying levels of car use, conditions and of course driver makes perfect sense for a standard production line map to run rich.... as already stated it adds a level of safety, but by no means is it running at its best efficiency and thats a fact regardless of whether you have spent billions of dollars to find out that conclusion or switched your brain on and achieved it for zilch. Subaru have not got it wrong, they just do what all other car manufacturers do...... but that does not mean that it's giving you the best for your requirements does it. Anyone that thought what you get out of the box is the only way, surely is more **** than anything in the whole world.

Regards,
Shaun.

Alberick

Apparently, I really openend a can there...?
Anyway, wasn't there a thread somewhere stating that the later MAF's are more robust than the earlier ones and that they could be identified by a coloured dot?

ALi-B

iTrader: (1)

I thought it was the other way round..the pre MY99 MAFs were more reliable.

Anyhoo. Pete, I guess you've never worked out the physics of less fuel+more air = bigger and much hotter bang (until you reach the point where there isn't enough fuel to mix evenly in the combustion chamber to ignite = missfire) , thus the invention of lean burn engines (refer to the May "fireball" combustion chamber as a nice well documented example). More power, but runs much hotter, and more likely to det. Seize a few 2stroke engines because the jets are too small and you'll learn alot more quickly an even better and explosive way to learn is to fit nitrous oxide to your car and not bother increasing the fueling map

ex-webby

Alberick,
Not at all... just healthy debate.

Ali-B,
Dont state facts as Pete thinks that is too ****..... although "****" physics have allowed us to create the combustion engine!

Pete likes to wind people up........ either that or he is thick beyond all recognition. It's a toss up at the moment to decide on which one!

Regards,
Shaun.

jonny gav

iTrader: (1)

i go for thick beyond all recognition after reading that little lot!

SiHethers

Alberick

Get your car checked out with a SM or deltadash, then you'll know whether you need a MAF replacement. And if you do, do it yourself rather than paying, it's dead easy.

Is Pete for real, I reckon it's got to be a wind-up?

And for general info, it's often the ignition advances that come with the fuel leaning that results in engine loss, as the ignition map is MAF based as well as the fuelling.

Cheers

Simon

PS the replacement MAFs do appear more robust as I've done 40,000 miles on my current one, WITH an induction kit, which isn't firmly secured and must vibrate a lot.

pslewis

I give up ..... the ***** have populated ScoobyNet!!

You're all foookin' mad I tell ye!!!

Barking Bonkers ..... **** Oil Changes, 'sensitive' MAF's, lost ECU's that need a new map, 'cocklink' fairy lights needed on dash to save engine, please say you are all winding me up??

I surely to god cannot be the only voice of reason on this BBS???

Pete

p1mark

the sad thing about this is that some one will actually come on here for genuine advice, look at pslewis's post count and think he must know what he is talking about, go away and potentially damage his engine.

i find it quite disturbing you sitting there smugly thinking up smart *** / wind up comments that could lead to some poor lads pride and joy being damaged.

pslewis

What???

Damage their engine by NOT carrying out the **** Oil Change Procedure??

Do me a favour, ring up your local Subaru Main Dealer and ask them if they fart about like a poxy old woman or just get on and change the oil like a friggin MAN!!?? They'll **** themselves laughing at you if you tell them they should disconnect the camsensor!!

Have a day off, FFS!!

Pete

p1mark

as already mentioned to you earlier in another thread, its the crank sensor. this thread happens to be about something different.

pslewis

Cam Sensor - Crank Sensor, whatever .............. it shouldn't be touched after an Oil Change!!

OFFICIAL Subaru line!!

So, if you claim I am misleading - then you also claim that Subaru are giving out wrong info???

Like I said, have a day off!!

Pete

Alberick

Uhhmmm, looks like a real sensitive issue and I'm not sure who to believe.

On one point it's sure that one should be on the safe side but then again I agree with pslewis that any "regular" Subaru dealer would probably laugh at you if you would ask them to disconnect whatever sensor before changing the oil as most of them just go ahead and do an oil change as they would on any other car. Do not misunderstand, I'm not taking sides here, I think this is just a fact. On my car, oil change was always done without any special procedure and I had no problems so far.

Coming back to the MAF sensor, the very first one went quite early whan the car was still new, this was with the original, unmodified Airbox and filter (with snorkel, resonator and everything that comes with it). Shortly after getting a new MAF under warranty I fitted an Apex'i induction kit that sits in an AVO Carbon box and the car did about 75000 km with this setup now without any MAF failure.
When the first MAF went, there was no "creeping upon me"; on the motorway I tried to pass a truck and suddendly the car lost power, no more boost, CEL light came on, and anything over 60 km/h would shut the engine off.
Maybe I'll just go "****" and fit one of those SECS, would that show me eventual failure codes to see if my MAF is on its way out?

Don't worry I know how to replace the MAF, already took it out once to fit it into a new housing (the old one had 2 screw "ears" broken off), but no matter if the garage does it or yourself, the damn thing still costs 120 Euro.

Ramon

Houghton

iTrader: (1)

Briefly, the idea of disconnecting the crank sensor is for priming the the oil system after it's been emptied. With the sensor disconnected, the ecu won't fuel or fire the plugs. Once the clean oil and filter are in place, the idea is to crank the engine on the key untill either the oil warning light goes out or pressure is indicated on an oil pressure guage, if you have one fitted. This ensures that the system sees some oil, i.e. the pick up is flooded and the pump primed ready for when the crank sensor is re-connected and the engine fires up.

The other '****' thing is to pre-fill the new oil filter with fresh oil. This takes quite a few minutes before all the air is out and the filter is fully wetted. I fill it the day before and leave it in the box to prevent dirt/dust getting in, but then I must be ****

If you have an oil pressure guage fitted, the time difference in registering pressure is quite considerable between cranking from the first fill to cranking after fill.

The MAF apparently isn't a black/white work/fail thing, it's progressive over a period of time. It's a hot wire with thermister (or some other temp reading device). Hot wire generates heat which is then read. The cooler the reading, the more air flowing. Presumably, over time, the temp reading part may get a coating of fine particles from smoke drawn in or whatever so doesn't see the true temp from the hot wire. This causes low readings to the ecu, which, because it's getting a reading thinks MAF is OK and fuels accordingly, i.e. low. therefore, lean running, and det.

The ecu reads the det and adjusts accordingly but it has finite limits of adjustment. When the limit is exceded, pop goes the engine.

That's my understanding, but do a search for MY 99 & 00 MAFs and oil change procedures.

Gerry.

pslewis

Could you please specify 'quite considerable'??

0.5 second?

1 second?

2 seconds?

'quite considerable' means absolutely nothing .....

Pete

pslewis

Please, NO - tell me you ARE joking!!!

FFS seek help FAST!!

Dear god, that is the saddest waste of life I have ever had the misfortune to read You must be a bundle of fun down the pub!

Pete

ps. I will allow myself the **** operation of prefilling the filter ........ as for leaving it overnight all wrapped up all cosy like - well, that is for the Premier League of the **** Practioner!! That has seriously worried me!! people like this are actually walking our streets!!

pslewis

What you fail to mention is that the Oil can ONLY drain the SAME as it does when you stop the car!!

NO MORE OIL COMES OUT THE ENGINE AT OIL CHANGE!!!!!

I will repeat that ................

THE ENGINE OIL STATE AFTER DRAINING THE OIL FOR A CHANGE IS THE SAME AS THE STATE THE ENGINE IS IN AFTER THE ENGINE HAS BEEN STOOD FOR A FEW MINUTES WITH ENGINE OFF!!!

Therefore, the **** Crank Sensor Procedure SHOULD be carried out EVERY morning ................... or it is all complete and utter BOLLOX!!!

And thats what it is .... Bollox!!!

Pete

p1mark

Pete.



Don’t be led into believing that Subaru or their dealers are completely fail safe in their advice. Dealers and the grease monkeys are under pressure to get the jobs out quick and to keep servicing costs down, and do not always do as thorough as job as I would prefer on my own car. Any little thing you can do to help longevity should be encouraged and not dismissed. Engines are designed to be put together as easily, cheaply and quickly as possible by people even less technically adept than yourself. Therefore things like oil priming systems and other good practices are risk assessed and skipped if it is thought that the risk is not enough to warrant the outlay in finance / labour / ease of build etc. Automotive manufacturers are aware of these things but it is a cut throat business and things like these are the first things swept under the carpet when over budget.



And before you ask, I am an engine designer for a major automotive manufacturer, and have in the past been a consultant for a number of well known motorsport teams.



If you feel I have claimed you to be misleading then I appologise humbly. I am sure you are not deliberately misleading but nonetheless some of your advice is unsound.



You do not need to be the world’s greatest engineer to understand that a couple of seconds without oil pressure is not a good thing. Or the worlds greatest intellect to understand that of the of 100’s of problems on this BBS blamed on a MAF problem, some of them probably were not MAF related, but as sure as eggs are eggs, some of them may have been avoided by a precautionary change.



I think that 99% of the people on here (thankfully) know that contrary to your own opinions, you are neither of the aforementioned. It’s the 1% that concerns me, and for their sakes you should refrain from inane ramblings on technical forums. Just stick to politics / football where opinions are opinions, and not black and white facts.



MAF’s detiorate – fact

Having no oil on start up is not good - fact



Not wishing to get involved in the ‘he knows more than you’ attitude rife on this forum, I think it is fair to point out that Bob Rawle eminently does know more than your good self!



And as for your last idea, you are really speaking out you’re a*se. The pick up is immersed in oil. And therefore oil is also retained in the pick up pipe up to a certain level. When you drain the oil out of the sump, it comes out of the pipe as well.



I will have my day off now, thanks for the kind offer!

dj219957

OK comments like this:
"I fill the Oil Filter the day before and leave it in the box to prevent dirt/dust getting in"
are not going to help us educate pete. Even i agree with him on this one. Prefill it yes (i do) there is no need to leave it over night for gods sake! PMSL

Alberick

Hehe, how "****" can this thread still become??

Ok, guys, summer's coming, go out for a walk get some fresh air, there's so many things in this world to discover other than disconnecting crank sensors or being scared of creeping MAF failures.

pslewis, don't be so harsh on other people, I'm also ****, proof: I have a Turbo Timer installed on my car and always let it run for 30 seconds no matter how my driving was and.......I have 17" gold wheels with red anodized "Rays" lightwheel nuts.

Come on guys, cheer up......

Ramon