Thought that since I had changed the MAF and the car was running along nicely and pulling so much better that I would treat myself to a dyno run this afternoon..
This is pre-MAF change..
(http://i2.photobucket.com/albums/y8/Turdbabe/torqueplot.jpg)
This is after..finally I break the 200 barrier, well 203.5 to be precise s:D :D s:D
(http://i2.photobucket.com/albums/y8/Turdbabe/EADyno2.jpg)
I am well chuffed, nearly 10 HP difference, quite amazing really how much difference the MAF can make if it isn't working right! I have no more farting around and no more blip in the acceleration. The difference to Simons car was quite amazing too - his felt like it was running out of breath and is now cured.
now who's pleased as pie s:wink: :wink: s:wink:
excellent result Liz s:D :D s:D
everybodys going to be buying new mafs now s:lol: :lol: s:lol:
Whats yours kicking out now Bossman?
Hi Liz
I am surprised that a change to the MAF had such an effect.
Did you have any problem with the old one that made you change it?
The engine management system is normally able to detect a slight degradation in MAF performance as so much else is being monitored on the engine (i.e. HEGO sensors), and then will adapt accordingly.
Even dirt on the MAF thermistor is unlikely to cause a big enough impact to fool the engine in to running rich.
Don't want to spoil your fun, but could this be down to dyno variation - were both runs done at the same place on the same rig?
i have no idea seeing as i dont have the car s:lol: :lol: s:lol:
still with SP but i will post the results, im interested to see how it drives compared to before!
Quote from: "andywood"The engine management system is normally able to detect a slight degradation in MAF performance as so much else is being monitored on the engine (i.e. HEGO sensors), and then will adapt accordingly.
Considering at WOT the ECU isn't even looking at the O2 sensors as it's running open-loop, how would they compensate for a bad MAF? (For a start when turbocharged you're driving the O2 sensors so far out of range of their sensitivity band they're useless at any point other than cruise or idle when you're maintaining stoic)
I think the most telling thing, even discounting the power difference, is that there is no longer a big hole in the power band up top - it's unlikely that would be down to dyno differences IMHO.
hasn't Dan had the VXR on both of those dyno's?
OK, so the HEGO example was a bad one considering it will be running open-loop,...
But, picking up on your point about the flat spot, surely you would expect a relatively uniform shift across the whole engine speed range with a problem MAF (taking into account engine speed and exponential output on MAF)?
Quote from: "kanujunkie"hasn't Dan had the VXR on both of those dyno's?
Not on either of them mate, only at the one that me and Mark tagged along with the IMOC boys and girls.
Quote from: "andywood"OK, so the HEGO example was a bad one considering it will be running open-loop,...
But, picking up on your point about the flat spot, surely you would expect a relatively uniform shift across the whole engine speed range with a problem MAF (taking into account engine speed and exponential output on MAF)?
No, its a heated sensor remember, if the sensors created a point in the temp scale where it resistance changes drastically then the ECU will relate that to a certain point in the map and fuel accordingly, creating a flat spot
Quote from: "Ekona"Quote from: "kanujunkie"hasn't Dan had the VXR on both of those dyno's?
Not on either of them mate, only at the one that me and Mark tagged along with the IMOC boys and girls.
could have sworn it was you s:roll: :roll: s:roll: , oh well
Well can you explain then Andy, why my car and my husbands were running like that had both run out of breath and are that much better both running on new MAFs, hardly a co-incidence really. I have driven my car pre and post changing MAF - the difference is like night and day, no blip in acceleration and no running out of puff - pulls right to the redline now..when the bloke that done the dyno says how much better it was than last time says something really. Trust me - the MAF has made the difference between the 2 dyno's.
Quote from: "Liz"Well can you explain then Andy, why my car and my husbands were running like that had both run out of breath and are that much better both running on new MAFs, hardly a co-incidence really. I have driven my car pre and post changing MAF - the difference is like night and day, no blip in acceleration and no running out of puff - pulls right to the redline now..when the bloke that done the dyno says how much better it was than last time says something really. Trust me - the MAF has made the difference between the 2 dyno's.
Currently just trying to eat my words! s:wink: :wink: s:wink:
Reason for my pessimistic approach to this one is that I spent a number of years working for DENSO with MAF sensors - I never saw anything like this in my time there, although the customer engines we were working on were large V8's and had much more complex EMS.
Doesn't matter what I say, you still got more power and a better running car for the Braintree bypass! s:D :D s:D
Quote from: "kanujunkie"Quote from: "andywood"OK, so the HEGO example was a bad one considering it will be running open-loop,...
But, picking up on your point about the flat spot, surely you would expect a relatively uniform shift across the whole engine speed range with a problem MAF (taking into account engine speed and exponential output on MAF)?
No, its a heated sensor remember, if the sensors created a point in the temp scale where it resistance changes drastically then the ECU will relate that to a certain point in the map and fuel accordingly, creating a flat spot
Quote from: "Ekona"Quote from: "kanujunkie"hasn't Dan had the VXR on both of those dyno's?
Not on either of them mate, only at the one that me and Mark tagged along with the IMOC boys and girls.
could have sworn it was you s:roll: :roll: s:roll: , oh well
OK, not trying to dig myself a complete hole here, but...
the maf has an external thermistor to measure air-in temp which should not be affecting this scenario at all.
In the MAF bypass duct there is the usual 'hot-wire' approach of arranging a heater element and thermistor in close proximity and wired in a wheatstone bridge styley. The electronics try to maintain a set heat transfer and therefore need to adjust when air-flow increases, thus determining mass air flow against a map programmed into the ems.
These elements are partial to build of general crap as particles will happily adhere to hot elements, but from my experience you would normally see a shift in output across the air-flow range.
I will make this my last comment on the subject as my shovel is starting to get worn out! s:wink: :wink: s:wink:
This is a bit boring, but to sway any doubters.... when Liz first had the car dyno'd one of the suspects was the MAF. we swopped mafs, and though Liz didn't get any benefit my car started to throw CEL's, which showed it running lean - and a culprit for this could be the maf. Now my defective brain started to tick and suddenly, TOCK!, I bought a new maf, and WHAHEY! feels like a new car, whereas it used to struggle through a "wall" at 4500+ revs now it knows no bounds (see "spotted" thread). Now, my car had had a bit of a wall at 5000 revs before we swopped mafs, so perhaps my original wasn't that good to start with.. coincidence to each have a defunct maf but possible, so... Liz gets a new maf and the result is not just 10bhp,
it is s:D :D s:D s:D :D s:D s:D :D s:D s:D :D s:D s:D :D s:D s:D :D s:D s:D :D s:D s:D :D s:D s:D :D s:D s:D :D s:D s:D :D s:D s:D :D s:D
Quote from: "andywood"the maf has an external thermistor to measure air-in temp which should not be affecting this scenario at all.
In the MAF bypass duct there is the usual 'hot-wire' approach of arranging a heater element and thermistor in close proximity and wired in a wheatstone bridge styley. The electronics try to maintain a set heat transfer and therefore need to adjust when air-flow increases, thus determining mass air flow against a map programmed into the ems.
These elements are partial to build of general crap as particles will happily adhere to hot elements, but from my experience you would normally see a shift in output across the air-flow range.
yeah i know how they work, standard hot wire setup. But you can get a scenario where the resistance breaks down at a certain temp. I have to agree that i've never seen it on a car before, but then again thats not my speciality, its yours. But we do see it on the aircraft from time to time and its generally due to the extrememes of temperature that they get subjected to and have to correct for
Just as a footnote to this thread - I have got a big thank you to say in public...and that is to the mods on here. There is a 10 page thread in the mods section dedicated to the problems that I have had with my car...they have all been a real huge support to me when I could of quite happily of parked it up somewhere and walked away.
Cheers guys - your the best! s:D :D s:D
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:
Let us know how you get on with it won't you?
Yes definatley.... I did try a maf off an mr2 I was putting a new engine into ... but it ran worse ..... But gonna try a fresh one ......... to be continued..........................
Can certainly vouch for it running well! Thanks Liz. (Un)fortunaltely I cant throw that kind of money at my '2. A properly nice to drive installation.
On the subject of MAF or any other sensor, it is sometimes seen that output is non linear or in error in part of the output range only. In the bridge, there is a varying amount of current being provided to heat the wire. It is easily possible that a termination somewhere in that heat balancing circuit is defective and at certain current / voltage levels changes resistance.
Chris
Quote from: "Liz"Thought that since I had changed the MAF and the car was running along nicely and pulling so much better that I would treat myself to a dyno run this afternoon..
This is pre-MAF change..
(http://i2.photobucket.com/albums/y8/Turdbabe/torqueplot.jpg)
This is after..finally I break the 200 barrier, well 203.5 to be precise s:D :D s:D
(http://i2.photobucket.com/albums/y8/Turdbabe/EADyno2.jpg)
I am well chuffed, nearly 10 HP difference, quite amazing really how much difference the MAF can make if it isn't working right! I have no more farting around and no more blip in the acceleration. The difference to Simons car was quite amazing too - his felt like it was running out of breath and is now cured.
"I have no more farting around.."
by farting do you bean, a bang sound a bit like a backfire? My car does this all the time.. I'm pretty sure it's not normal, even tough I have TTE exhaust + gutted precats. When the engine is hot.. it's "horrible", it bangs allmoust everytime I drop the gas. it's not horrible, it's quite cool.. but sumthing shouldn't be good, I wonder what it is, but I don't have a clue where to start...
Quote from: "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:
I don't have any walls so to say, and my car runs pretty fast. But at around 4000Rpm I can totally feel the diference in power (more power, like the engine has reached the rev range it likes to live on)
Quote from: "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
Your talking about the normal noise like a "pop" that you get with gutted precats and a better than standard exhaust - quite normal and lots of fun. My turbo has just started to do it as well! Personally I like it.
My farting around referred to the car just feeling like she wasn't running properly and not pulling and being sluggish. Hope that helps.
Quote from: "Liz"My farting around
anybody care to comment? s:twisted: :twisted: s:twisted:
Quote from: "kanujunkie"Quote from: "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 ???
Quote from: "kanujunkie"Quote from: "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.
Quote from: "kanujunkie"Quote from: "Liz"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:
Quote from: "mr2mark"Quote from: "kanujunkie"Quote from: "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 ???
have a read and a watch, but it kicks in around that rpm
m http://en.wikipedia.org/wiki/VVT-i (http://en.wikipedia.org/wiki/VVT-i) m
m http://www.youtube.com/watch?v=9A6S1NUjg_A (http://www.youtube.com/watch?v=9A6S1NUjg_A) m
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.
Quote from: "mikevernon@talktalk.net"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.
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 .........
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:
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 .....
Fingers crossed! s:) :) s:)
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.
Quote from: "mikevernon@talktalk.net"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.
Quotebut 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:
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:?
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?
Quote from: "mikevernon@talktalk.net"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......
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 :D s:D
Toyota - its about £107 with VAT
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:)
mr2mark - you may just want to hang bank on getting a MAF for the moment.
Quote from: "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"
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
I've been meaning to replace mine for a long time. Cleaning only removes so much gunk.
Quote from: "spit"mr2mark - you may just want to hang bank on getting a MAF for the moment.
Quote from: "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"
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
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.
dont know if these are the same mafs
m http://cgi.ebay.co.uk/New-Air-Flow-Mete ... dZViewItem (http://cgi.ebay.co.uk/New-Air-Flow-Meter-Toyota-Corolla-Yaris-Yaris-Verso-RAV_W0QQitemZ160086045226QQihZ006QQcategoryZ10428QQrdZ1QQssPageNameZWD1VQQcmdZViewItem) m
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:? )
hes a uk seller?
Quote from: "perry190"hes a uk seller?
I'm an idiot s:oops: :oops: s:oops:
s;) ;) s;) s:lol: :lol: s:lol:
The O ring comes with a new maf - still smarting at the price of those ones.. s:evil: :evil: s:evil:
Quote from: "Liz"The O ring comes with a new maf - still smarting at the price of those ones.. s:evil: :evil: s:evil:
I bet the change of o ring gave you the improvements Liz not the new MAF s:wink: :wink: s:wink: You probably had a leak (in joke mode) s:wink: :wink: s:wink:
s:lol: :lol: s:lol:
So, do we think these EBay MAFs are some sort of pattern replacement?
Can't see any reference to DENSO or the embossed markings on the top cap. Hmmm, decisions.
just to drag this up again, just found this in the BGB
QuoteHeated oxygen sensor heater control system
The heated oxygen sensor heater control system turns the heater on when the intake air volume is low (Temp. of
exhaust emissions is low), and warms up the heated oxygen sensors (Bank 1 sensor 1, bank 1 sensor 2, bank 2 sensor 1)
kinda explains why now
Quote from: "spit"So, do we think these EBay MAFs are some sort of pattern replacement?
In answer to my own question, the EBay 'NAFs' are
NOT[/u] the genuine Denso part, and although the part number matches our car they
DON'T[/u] have the same hotwire construction/configuration as the one I've taken off. s:? :? s:? The body is a cheesier plastic too, although they do have a metal seating plate and O-ring.
I had some very dangerous AFR levels with it this morning ... and very nearly posted up to warn you not to bother ... but its settled down a bit now.
I'll persevere and see how it beds down after some ECU learns and get back to you. Could go either way s:wink: :wink: s:wink:
Interesting, could be the reason why Waynes didn't react well to the one he purchased off of ebay and was ok with my Mr T one on it, he hasn't been around on here for a while, hope he comes back and reads this.
Anyone got the part number for the MAF?
My mrT is being a bit thick at the moment, and aparently mr2's dont have MAF's
22204-22010
Right, here's my take on the EBay generic MAF.
Its OK. It works, and it (eventually) sends an appropriate signal to the ECU. Under load its bang-on and has cured my wandering AFR issue a treat. So if you need a replacement it will do the job.
BUT
It takes an age to settle and send a reliable voltage to the ECU. Normally, when you start-up from cold, your car should run in the AFR12s and13s until it is warm, when it settles to 14.7ish.
With the generic MAF the start-up AFR is dangerously high and you don't get this choke effect at all. Haven't quite worked out why s:? :? s:? , but if you need to get out of your car soon after starting it (to shut the garage door, for example), don't rely on this MAF to be looking after your car while your foot is away from the accelerator. s:shock: :shock: s:shock:
The other issue is that the MAF is a little slower than the stocker in dropping its voltage when you lift off. If you like pops and bangs on a gear-change this probably won't bother you too much!
So, it looks like the adage "you get what you pay for" applies.
I'm going to stick with it for a while - may be able to tune some of the issues out with the EManage. But the old MAF is riding around with me just in case s:wink: :wink: s:wink: