Air Flow (Plenum) Meter Premature Death!
Discussion
Black Chim said:
Can anyone tell me how long a healthy airflow meter should last? Even if its a recon unit from a reliable supplier should it last more than 24 months circa 5500 miles ?
My local independent is being very sympathetic but my wallet is getting really nervous !
You might find a few on ebay at the mo given the number of aftermarket ECUs being fitted... prolly +1 soon tooMy local independent is being very sympathetic but my wallet is getting really nervous !
There are no moving parts so it could last the lifetime of the car. Even with a good air filter though, a very fine black dust will settle on the hot wire over many years of use. And it operates in a harsh environment so I suppose the electronic components will eventually suffer from repeatedly being heated up/cooled down.
Black Chim said:
I noticed ebay sales, I am right assuming 'one size fits all' or is that a really naive statement?
Original lasted circa 70,000 miles. Recon lasted circa 6000 miles & failed emissions on MOT (used a different independent this time for service !).
If it's the same part number in good working order then they are interchangeable (but would need to have the trim adjusted). There are plenty of components that routinely fail and could cause an emissions test failure, but AFM failures aren't at all common. The chances of two failing in short order seem very slim indeed. Are you sure it's actually faulty?Original lasted circa 70,000 miles. Recon lasted circa 6000 miles & failed emissions on MOT (used a different independent this time for service !).
Black Chim,
I have a spare one knocking around the garage if you're interested. Its for the 5 ltr so I think its the 5AM version.
I bought a known good 2nd hand one from Tim at ACT when I was trying to get to the bottom of my fuel consumption problem. Turned out there was nothing wrong with the Airflow meter though.
Just looking to recoup some of the money it cost me at the time.
Let me know if you're interested.
Phil
I have a spare one knocking around the garage if you're interested. Its for the 5 ltr so I think its the 5AM version.
I bought a known good 2nd hand one from Tim at ACT when I was trying to get to the bottom of my fuel consumption problem. Turned out there was nothing wrong with the Airflow meter though.
Just looking to recoup some of the money it cost me at the time.
Let me know if you're interested.
Phil
Edited by Philr on Wednesday 4th June 02:23
GreenV8S said:
Black Chim said:
I noticed ebay sales, I am right assuming 'one size fits all' or is that a really naive statement?
Original lasted circa 70,000 miles. Recon lasted circa 6000 miles & failed emissions on MOT (used a different independent this time for service !).
If it's the same part number in good working order then they are interchangeable (but would need to have the trim adjusted). There are plenty of components that routinely fail and could cause an emissions test failure, but AFM failures aren't at all common. The chances of two failing in short order seem very slim indeed. Are you sure it's actually faulty?Original lasted circa 70,000 miles. Recon lasted circa 6000 miles & failed emissions on MOT (used a different independent this time for service !).
That's correct: go for one with the same Land Rover part number (usually ERR5198). There are different 5AMs out there, I have a spare off a 1993 4-litre Jaguar (Jaguar part number DBC10852). It's physically identical and it works, but it has no trimmer (just a blind hole in the casting where it would be).
[/quote]
Im puzzled....whats the 'trimmer'? What does this do?
Had to replace my AFM last year before le-mans and the dealer offered a new one at about £800 or a refurb at half that...went for the refurb but must admit I havent noticed a trimmer..?
[/quote]
Im puzzled....whats the 'trimmer'? What does this do?
Had to replace my AFM last year before le-mans and the dealer offered a new one at about £800 or a refurb at half that...went for the refurb but must admit I havent noticed a trimmer..?
Dont worry about adjusting the trimmer, its bypassed on cars running the catalyst fuel map, as the lambda feedback does the adjustments for you. If its failed emmisions you need to know which pollutant its failed on to make judgement on why. At its most basic, a high CO is over rich, High Lambda is over lean, high hydrocarbons are a misfire, but these come in various combinations that will point towards the failing item. I really would not suspect the AFM at this point. This comes from an MOT test site, but its a little vague for my liking, but better than nothing:
Basic fault finding for advanced emission test failures:
1. If a vehicle fails for high CO at idle and /or fast idle then.... if Lambda is too low, the mixture is too rich. This can also be caused either by a misfire or by a faulty Lambda sensor. If it's running very rich, the 02 and HC will be higher than normal.
2. if it has a high Lambda and high 02 (0.5 to 1.5%), the "CAT" could be faulty. Before condemning it make sure its hot enough to work, the Lambda and other sensors are working OK and the exhaust downpipe hasn't got any leaks.
3. if the vehicle fails for high HC then ...if the CO passes, the vehicle is probably misfiring. Or if the CO fails and the Lambda reading is too low, the mixture is probably too rich and it may also be misfiring.
4. if the CO fails, the Lambda reading is high and the O2 reading is high (0.5 to 1.5%) the "CAT" could be faulty. Again check out the simple measures above before condemning it.
5. if the Lambda fails then...if its too high the Lambda sensor may be faulty, the mixture may be too weak or there may be a hole in the exhaust downpipe. If Lambda is too low the sensor may be faulty, the mixture may be rich or the vehicle may be misfiring.
A low Lambda reading from an MOT means over rich and a higher number (greater than1) indicates a lean condition.
12.6:1 - max power - lambda of 0.86
14.7:1 - ideal combustion (chemically) - lambda of 1.00
15.4:1 - max economy - lambda of 1.05
However, the voltage from the back of probe does in fact rise when more fuel is in the mixture. (in reverse to the MOT test results).
Let me know your readings.
Mark
Basic fault finding for advanced emission test failures:
1. If a vehicle fails for high CO at idle and /or fast idle then.... if Lambda is too low, the mixture is too rich. This can also be caused either by a misfire or by a faulty Lambda sensor. If it's running very rich, the 02 and HC will be higher than normal.
2. if it has a high Lambda and high 02 (0.5 to 1.5%), the "CAT" could be faulty. Before condemning it make sure its hot enough to work, the Lambda and other sensors are working OK and the exhaust downpipe hasn't got any leaks.
3. if the vehicle fails for high HC then ...if the CO passes, the vehicle is probably misfiring. Or if the CO fails and the Lambda reading is too low, the mixture is probably too rich and it may also be misfiring.
4. if the CO fails, the Lambda reading is high and the O2 reading is high (0.5 to 1.5%) the "CAT" could be faulty. Again check out the simple measures above before condemning it.
5. if the Lambda fails then...if its too high the Lambda sensor may be faulty, the mixture may be too weak or there may be a hole in the exhaust downpipe. If Lambda is too low the sensor may be faulty, the mixture may be rich or the vehicle may be misfiring.
A low Lambda reading from an MOT means over rich and a higher number (greater than1) indicates a lean condition.
12.6:1 - max power - lambda of 0.86
14.7:1 - ideal combustion (chemically) - lambda of 1.00
15.4:1 - max economy - lambda of 1.05
However, the voltage from the back of probe does in fact rise when more fuel is in the mixture. (in reverse to the MOT test results).
Let me know your readings.
Mark
I don't have exact readings but here is the MOT failure report....
Fast idle carbon monoxide excessive & hydrocarbons excessive
However independent first advised it was the lambda sensors which they described as dirty, then they put a spare AFM on, ran the car for a bit, the Lambda sensors cleaned up & the MOT passed fine.
What do you think ?
Fast idle carbon monoxide excessive & hydrocarbons excessive
However independent first advised it was the lambda sensors which they described as dirty, then they put a spare AFM on, ran the car for a bit, the Lambda sensors cleaned up & the MOT passed fine.
What do you think ?
Lambdas can get carbon on them, that will clean off when the mixture is corrected. In terms of failure of the AFM, its voltage output would have to be considerably too high to get it to overfuel beyond the point the ECU can control the mixture, about an extra .5 of a volt or so at tickover. The ECU thinks the engine is drawing more air than it is, so it puts more fuel in. Dont throw the old AFM away, its hot wire might just need cleaning if the car runs ok apart from the high CO.
If theres no catch these look a bargain
http://cgi.ebay.co.uk/NEW-Air-flow-mass-meter-sens...
Just read it again - it does say it fits but is different to the picture - sounds like a bit of a catch to me!
http://cgi.ebay.co.uk/NEW-Air-flow-mass-meter-sens...
Just read it again - it does say it fits but is different to the picture - sounds like a bit of a catch to me!
Edited by Barkychoc on Wednesday 4th June 22:44
The hot wire is visable through a small hole on the side of the intake of the AFM. There are 2 small "jumpers" across a couple of posts.
http://www.g33.co.uk/images/airflowport.jpg
One is red glass and is a thermistor. The other is a rough grey wire,(the hot wire) that gets caked with muck To really clean it, you have to strip all the electronics out that I would not recommend, although a good blast of easy start through the hole over the wire might be enough to clean it (Not when the cars running!!). I'll have a closer look to see if you can get at the sensor by splitting the casting, in preference to pulling the electronics out. The hot wire itself is only about 2mm long, so a magnifying glass is recommended. As for the Ebay ones- may be a Chinese replica, as he says they dont look the same, but I dont know for sure. Its certainly a good price.
Mark
http://www.g33.co.uk/images/airflowport.jpg
One is red glass and is a thermistor. The other is a rough grey wire,(the hot wire) that gets caked with muck To really clean it, you have to strip all the electronics out that I would not recommend, although a good blast of easy start through the hole over the wire might be enough to clean it (Not when the cars running!!). I'll have a closer look to see if you can get at the sensor by splitting the casting, in preference to pulling the electronics out. The hot wire itself is only about 2mm long, so a magnifying glass is recommended. As for the Ebay ones- may be a Chinese replica, as he says they dont look the same, but I dont know for sure. Its certainly a good price.
Mark
Edited by blitzracing on Thursday 5th June 12:04
Edited by blitzracing on Thursday 5th June 13:15
You cant get at the the hot wire itself without a complete strip down, so best efforts would only involve a good spray of cleaner and possibly a cotton bud through the hole. Heres a picture of the assembly,the thick grey bit is the hot wire that you might see muck on.
http://www.g33.co.uk/images/hot_%20wire.jpg
Mark
http://www.g33.co.uk/images/hot_%20wire.jpg
Mark
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