What a difference a MAF makes.....

[kanujunkie]

My farting around

anybody care to comment?  s:twisted: :twisted: s:twisted:

[mr2mark]

Hi I have that "wall" at about 4800 rpm... Ive changed coil packs, injectors , spark plugs , even cleaned the MAF ..... After reading this subject I am definatly going to try a new MAF. ............ Then I mightbe able to overtake people again without having to pull back in all red faced   s:oops: :oops: s:oops:

could also be the VVTI

what

[Liz]

My farting around

anybody care to comment?  s:twisted: :twisted: s:twisted:

***shakes fist at Stu***

Its what I thought was wrong with mine when it hit the wall, however, it does throw a code if there is something wrong with it, if you haven't got a CEL its unlikely to be it.

[Anonymous]

My farting around

anybody care to comment?  s:twisted: :twisted: s:twisted:

It's the dog. Or so I'm led to believe   s:twisted: :twisted: s:twisted:

[kanujunkie]

Hi I have that "wall" at about 4800 rpm... Ive changed coil packs, injectors , spark plugs , even cleaned the MAF ..... After reading this subject I am definatly going to try a new MAF. ............ Then I mightbe able to overtake people again without having to pull back in all red faced   s:oops: :oops: s:oops:

could also be the VVTI

what

have a read and a watch, but it kicks in around that rpm

 m http://en.wikipedia.org/wiki/VVT-i m

 m http://www.youtube.com/watch?v=9A6S1NUjg_A m

[Anonymous]

I've recently replaced the maf sensor on my BMW 330 Diesel and the car was instantly transformed.  I had run the car for almost a year and been really disappointed by its lack of performance, then rather than pay BMW I did some research on the internet and found that the maf was a likely culprit.  Luckily the simple diagnostic test is to just unplug the electrical connector.  I did this and the transformation was dramatic - the 50 to 70mph  acceleration figure was literally halved.  
I bought a new (non-Bosche) one off eBay for £50 instead of around £200 from BMW, and fitting took me 10 minutes.  The only problem is that I can't really tell the difference between having the new maf and just having the maf disconnected, so I can't be certain that the new one is working, but the performance is now what it should be and I'm getting 40.9 mpg overall, so I assume that it is working properly.

The reason that it seems to work with the maf disconnected is presumably that the ecu compensates for the lack of signal from the maf sensor and operates in some king of emergency mode, thereby restoring the performance.  

I recently talked to my Toyota dealer about removing the pre-cat.  He strongly advised against it, suggesting that it would upset the engine management system.  He thought it likely that it would trigger the warning light or at least cause the ecu to alter the mixture/ignition settings to compensate for the change, which could eventually lead to other problems.    Having just had experience of the way my BMW's ecu compensated for the lack of a maf sensor, I could understand what he meant.  He also managed to convince me that engine failures have been extremely rare and that pre-cat failure was not the cause, so I've decided to leave mine alone.

[aaronjb]

so I've decided to leave mine alone.

That's a shame, because your Toyota dealer was spouting unadulterated crap regarding removing the precats altering the mixture in any way whatsoever.

Dealers like that should be kicked in the head, repeatedly, until the basic principles of the engine management systems on the cars they are meant to sell and maintain sinks in.

Still, they will be more than happy to take a couple of thousand pounds off you should you need a new engine, so it's win-win for them, really.

[mr2mark]

Yep I know all about what happens and that... but is there a problem with them ?? does it stop working ?? The car used to rev clear all the way up and was impressive .... now its embarrassing   s:oops: :oops: s:oops:  
      any info would be appreciative .........

[Liz]

My car and my husbands (mister rebel) were both chucking CEL's saying that the O2 sensors had gone, the MAF cured these as well.  Have you got anyone near to you - as there are plenty of Newcastle members - that you could swop with for a few hours and try - remember to reset ecu.  s:wink: :wink: s:wink:

[mr2mark]

Oh that sounds alot like mine..... c.e.l on and when I put the garages laptop on and it told me "bank 1 sensor 2 heater circuit" I am going to order a new maf 1st thing in morning......  ooh I hope this is the cure .....

[Liz]

Fingers crossed!   s:) s:)

[Anonymous]

Aaronjb
Perhaps this belongs in another thread, but it would seem logical to me that pre-cat removal should affect the way the ecu controls the mixture because it will change the readings from the O2 sensors as well as affecting the exhaust flow.  
I also have to say that despite your comments, the Toyota technician did convince me that he knew what he was talking about.  He was aware of speculation about pre-cat failure being a possible cause of engine failure, but in his experience the dealership had not come across one single example.   He had come across engine failures caused by low oil level, in some cases caused by excessive oil consumption resulting from clogged piston ring drains.  In fact he was very forthcoming and seemed very knowledgable on the subject, and there was no reason why he should conceal anything.  Having just bought an MR2 and read all the various opinions on here about pre-cats I was becoming quite worried, but I'm now inclined to trust the opinion of somebody in a better position to judge the evidence.

[aaronjb]

Perhaps this belongs in another thread, but it would seem logical to me that pre-cat removal should affect the way the ecu controls the mixture because it will change the readings from the O2 sensors as well as affecting the exhaust flow.  

So, how exactly will it change the readings from the O2 sensors, considering the CATs are after the sensors?  (Don't count the third O2, since it does not control fuelling in any way)

And if exhaust flow was such a big problem, why haven't all the folks with gutted headers or che headers started exploding I wonder?

Perhaps because the dealer was talking crap.

but I'm now inclined to trust the opinion of somebody in a better position to judge the evidence.

Well, it's nice to know what you think of the years of gathered evidence and knowledge both here and on SC.  I'll save this one for when your engine goes bang..   s:roll: :roll: s:roll:

[Liz]

I had my first '2's cats gutted years ago - it never threw a code after they were taken out, never threw them before either.  I have also seen at Rayleigh Toyota 3 MR2's outside, I was out with the technician in my car and when I asked him what they were in for - they were all engine failures.   We are not saying on this forum that this will happen to every single '2 - it happens though - Fact.  Ekonas went again just after he had had them replaced. Obviously its up to you what you do and who you believe.

And yes - we have rather drifted from original post   s:? :? s:?

[Anonymous]

Regardless of whether or not premature engine failures are down to precat failure or not based on a vast amount of collective experience I can tell you that of all the members who have removed their precats (dozens & dozens) not one has reported a problem with CEL or engine management issues.

I sit on the fence on the precat issue myself - may be a cause of engine failure may be a symptom but it does happen and why take the risk?

[kanujunkie]

I also have to say that despite your comments, the Toyota technician did convince me that he knew what he was talking about.  He was aware of speculation about pre-cat failure being a possible cause of engine failure, but in his experience the dealership had not come across one single example.  

must be the only garage in the country then that hasn't had to change one because of precats. We have documented evidence on the forum of loads of cases which have ended in engine replacements, if your mechanic wants to argue against this evidence then feel free to get him to come on here. This even goes to the length that a guy in Germany tried to take toyota to court a couple of years back. So please one mechanic against the knowledge of several forums across the world......

[mr2mark]

Just been looking around on the net for a maf sensor..... Does anyone know where to buy one ..... and is there an uprated sensor ??
any info welcome ....   s:D s:D

[Liz]

Toyota - its about £107 with VAT

[loadswine]

At least we can remove the maf sensors on the 2 without special tools that are next to impossible to get. My other car has a VW maf and that has 5 pointed security torx screws that bits are only available under licence, or if you know someone specially connected in the trade.

Re the slight thread drift, if its a choice between a Mr T mechanic or a knowledgable member of our community, its a no brainer, Mr T will lose every time. Our members have nothing to gain from their advice other than trying to help others, I'll leave you to figure out what the dealer has to gain.

Changing over a possibly sick maf is a great idea and will give instant indication if that is the offending part. Most members would help out another 2 owner by swapping , if asked. Bet Mr T don't offer that one!  s:) s:)

[spit]

mr2mark - you may just want to hang bank on getting a MAF for the moment.

Oh that sounds alot like mine..... c.e.l on and when I put the garages laptop on and it told me "bank 1 sensor 2 heater circuit"

IIRC Liz's CEL was related to the O2 triggering a lean code .... not due to the heater circuit (which would trigger the CEL you got if its outside of tolerance or open circuit).

Plenty written about the heater circuit on the O2 sensor across the forum.

Of course I may be wrong - so much has been written and I haven't taken it all in.   s:oops: :oops: s:oops:  Perhaps someone more in the know can confirm?

Ste

[Anonymous]

I've been meaning to replace mine for a long time.  Cleaning only removes so much gunk.

[kanujunkie]

mr2mark - you may just want to hang bank on getting a MAF for the moment.

Oh that sounds alot like mine..... c.e.l on and when I put the garages laptop on and it told me "bank 1 sensor 2 heater circuit"

IIRC Liz's CEL was related to the O2 triggering a lean code .... not due to the heater circuit (which would trigger the CEL you got if its outside of tolerance or open circuit).

your right mate, one of them was P0420

[Liz]

That was the last code that it threw the P0420 - I also had a P141 and had to replace the sensor.  When my old MaF went onto Simons car his CEL said that it needed both O2 sensors, again the MAF got rid of those codes.

[Anonymous]

dont know if these are the same mafs


 m http://cgi.ebay.co.uk/New-Air-Flow-Mete ... dZViewItem m

[spit]

Good find! Same part number as ours.

You may need to purchase the O-ring separately - that'll be another 50 quid from MrT!  s:wink: :wink: s:wink:

(& presumably import duties for the MAF to cover too - with Parcelforce that probably means an additional £20 admin fee  s:? :? s:?  )