Replacement MAF's for the Diesel 75
A great deal has been asked and written about the MAF (the Mass AirFlow) sensor over the years. Mainly discussion has been around deciding whether a MAF output is in or out of spec. plus the very high costs of buying replacements for one which has drifted out of spec. or failed.
In attempts to reduce the costs, many in the past have bought cheap copies and / or 'compatible' ones and been disappointed with the results or paid for it in extra fuel consumed. These really are a waste of money, likely no better than your old one at best - avoid.
There is only one model of sensor suitable for the 75 and it is made by Bosch and should bear a model number ending in 029, even some of the fakes look the part and have the correct number.
It is important that the correct sensor is installed and that it produces accurate airflow figures, because the ECU depends upon it to decide how much diesel to inject for each stroke. Too much and mpg suffers, too little and performance suffers.
Recently in this thread http://ift.tt/XPhn9x
Then later in this thread - http://ift.tt/XPhnpP
Several off us got our heads together to try to end some of the confusion and attempt to find a cheaper genuine source for the correct MAF and also see if some alternative way could be found to test MAF's other than a T4 session.
The first thing we needed was the 'alternative' to using T4 and we found cheap diagnostic kits of numerous sources, would produce data from the MAF, but not in a form we could compare directly to the T4 data and Rover's data. We solved that by calculation and here are the results, as worked out by Okenora -
@780 rpm
MIN - 440mg/st = 11.44 g/s = 1.51 lb/min
OPT - 475mg/st = 12.35 g/s = 1.63 lb/min
MAX - 500mg/st = 13.00 g/s = 1.71 lb/min
@3000 rpm
MIN - 650mg/st = 65.00 g/s = 8.59 lb/min
OPT - 680mg/st = 68.00 g/s = 8.99 lb/min
MAX - 720mg/st = 72.00 g/s = 9.52 lb/min
The first column is the results you should expect for a good MAF as on a T4. The second and third columns are the data form usually produced by various general purpose diagnostic units. The engine should be up to temperature when conducting the tests and at 88C and your measurement results should be as close as possible to the OPT or Optimum figures shown. If below the MAX or MIN figures, your MAF needs to be replaced.
Now you have no excuse for not being able to test your MAF and decide whether it is out of spec..
Now for a source for a replacement, genuine Bosch sensor, of the correct spec. and at a very reasonable cost...
Certain car manufacturers have taken Bosch to court over Bosch's insistence on selling sensors in a housing at an inflated price. Unfortunately Rover was no more when this happened, so we were stuck with paying the inflated price. Bosch's line was that each sensor is specially calibrated to each housing, or individual housing. We now know this is entirely untrue, having transferred two (so far) 029 sensors from a BMW housing, into our 75 and checked the calibration - finding it to be spot on.
One fly in the ointment is that doing this, breaking the housing to sensor seal, we loose the warranty, but is the warranty worth paying an extra £50 to £80 ?
The second fly, is that we have so far only checked the calibration on ordinary general purpose diagnostic units, we still need to check they match the T4's method of checking the calibration.
So you you buy this one at your own risk, but we think the risk is quite tiny.
This Bosch MAF is included in a housing which contains the identical sensor to ours - same part number. Remove the MAF sensor from its BMW housing and transfer it carefully straight into your 75's housing - it will then be as good as new, correct and genuine Bosch sensor for (at current date) just £71.38 plus £5 P+P
http://ift.tt/XPhnpU
Some sellers have already cottoned onto this, buying from the same source, simply taking them out of the housing and are selling just the sensor for some £20 to £30 more than the above price.
__________________
In attempts to reduce the costs, many in the past have bought cheap copies and / or 'compatible' ones and been disappointed with the results or paid for it in extra fuel consumed. These really are a waste of money, likely no better than your old one at best - avoid.
There is only one model of sensor suitable for the 75 and it is made by Bosch and should bear a model number ending in 029, even some of the fakes look the part and have the correct number.
It is important that the correct sensor is installed and that it produces accurate airflow figures, because the ECU depends upon it to decide how much diesel to inject for each stroke. Too much and mpg suffers, too little and performance suffers.
Recently in this thread http://ift.tt/XPhn9x
Then later in this thread - http://ift.tt/XPhnpP
Several off us got our heads together to try to end some of the confusion and attempt to find a cheaper genuine source for the correct MAF and also see if some alternative way could be found to test MAF's other than a T4 session.
The first thing we needed was the 'alternative' to using T4 and we found cheap diagnostic kits of numerous sources, would produce data from the MAF, but not in a form we could compare directly to the T4 data and Rover's data. We solved that by calculation and here are the results, as worked out by Okenora -
@780 rpm
MIN - 440mg/st = 11.44 g/s = 1.51 lb/min
OPT - 475mg/st = 12.35 g/s = 1.63 lb/min
MAX - 500mg/st = 13.00 g/s = 1.71 lb/min
@3000 rpm
MIN - 650mg/st = 65.00 g/s = 8.59 lb/min
OPT - 680mg/st = 68.00 g/s = 8.99 lb/min
MAX - 720mg/st = 72.00 g/s = 9.52 lb/min
The first column is the results you should expect for a good MAF as on a T4. The second and third columns are the data form usually produced by various general purpose diagnostic units. The engine should be up to temperature when conducting the tests and at 88C and your measurement results should be as close as possible to the OPT or Optimum figures shown. If below the MAX or MIN figures, your MAF needs to be replaced.
Now you have no excuse for not being able to test your MAF and decide whether it is out of spec..
Now for a source for a replacement, genuine Bosch sensor, of the correct spec. and at a very reasonable cost...
Certain car manufacturers have taken Bosch to court over Bosch's insistence on selling sensors in a housing at an inflated price. Unfortunately Rover was no more when this happened, so we were stuck with paying the inflated price. Bosch's line was that each sensor is specially calibrated to each housing, or individual housing. We now know this is entirely untrue, having transferred two (so far) 029 sensors from a BMW housing, into our 75 and checked the calibration - finding it to be spot on.
One fly in the ointment is that doing this, breaking the housing to sensor seal, we loose the warranty, but is the warranty worth paying an extra £50 to £80 ?
The second fly, is that we have so far only checked the calibration on ordinary general purpose diagnostic units, we still need to check they match the T4's method of checking the calibration.
So you you buy this one at your own risk, but we think the risk is quite tiny.
This Bosch MAF is included in a housing which contains the identical sensor to ours - same part number. Remove the MAF sensor from its BMW housing and transfer it carefully straight into your 75's housing - it will then be as good as new, correct and genuine Bosch sensor for (at current date) just £71.38 plus £5 P+P
http://ift.tt/XPhnpU
Some sellers have already cottoned onto this, buying from the same source, simply taking them out of the housing and are selling just the sensor for some £20 to £30 more than the above price.
__________________
from the last news http://ift.tt/1x2G1CZ
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publié par vb @ 14:30
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