Replacement MAF's for the Diesel 75

[HarryM1BYT]

Originally Posted by johnnyb44

I've noticed "the warmer the days are " the less my car does to the gallon with the maf unplugged. At the moment im regularly getting around 45 to the gallon (brim to brim) as at the height of summer it was around the 41 / 42. to the gallon. Has this got anything directly to do with the maf unplugged ?

That would be true working MAF or unplugged. Colder air provides a more dense air charge, which is why the incoming air temperature sensor in the MAF is also important. The whole point of the intercooler, is to attempt to cool the air.

[kmtranter]

I'm looking at changing the MAF Sensor and noted from harrys post its possible to change just the sensor, is the following item on ebay a worthwhile purchase
http://www.ebay.co.uk/itm/NEW-MASS-A...item20cdd21d71

[HarryM1BYT]

Originally Posted by kmtranter

I'm looking at changing the MAF Sensor and noted from harrys post its possible to change just the sensor, is the following item on ebay a worthwhile purchase
http://www.ebay.co.uk/itm/NEW-MASS-A...item20cdd21d71

Sorry, your link seems not to work - besides which, this is what I said in post #1 of this thread - '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.'

So in answer to your question - NO, it will be an high risk gamble, but the choice is entirely yours.

[EDIT] Link is now working. It uses the words 'equivalent to' which suggests it is a copy of the Bosch item. As many have found there is only one which works and works properly and that is the correct, genuine Bosch item. Why waste your money? These sellers rely on most customers not knowing how to test them. Now we know how to test them.

[Johnny2R]

Originally Posted by HarryM1BYT

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.

I bought a new MAF sensor (the recommended Bosch on from the MAF Shop in the BMW housing) a couple of weeks ago and was delighted with what it did for the 160 Remap. I wish I'd got around to measuring the figures immediately after buying it. At the weekend I didn't get quite the same sensation of performance from the car as I had done in the previous week or so, but I thought I must just have got used to it.

Nonetheless, today I decided to measure the MAF output using Torque Pro with an OBD reader, and was a little surprised by the results. At 780rpm it's showing 14.2 g/s, rather more than the MAX in the quoted table. It's difficult to keep the revs exactly at 3000rpm, but it was showing something like 71 g/s, once again slightly on the high side (but within limits).

Any idea why this might be so far out when idling, and what the effect might be?

[HarryM1BYT]

Originally Posted by Johnny2R

I bought a new MAF sensor (the recommended Bosch on from the MAF Shop in the BMW housing) a couple of weeks ago and was delighted with what it did for the 160 Remap. I wish I'd got around to measuring the figures immediately after buying it. At the weekend I didn't get quite the same sensation of performance from the car as I had done in the previous week or so, but I thought I must just have got used to it.

Nonetheless, today I decided to measure the MAF output using Torque Pro with an OBD reader, and was a little surprised by the results. At 780rpm it's showing 14.2 g/s, rather more than the MAX in the quoted table. It's difficult to keep the revs exactly at 3000rpm, but it was showing something like 71 g/s, once again slightly on the high side (but within limits).

Any idea why this might be so far out when idling, and what the effect might be?

There could be a number of reasons...

Engine temperature, air leaks, EGR leaking or not closing properly, or choked up. I would suspect an issue with the engine, rather than the new MAF.

[Johnny2R]

Originally Posted by HarryM1BYT

There could be a number of reasons...

Engine temperature, air leaks, EGR leaking or not closing properly, or choked up. I would suspect an issue with the engine, rather than the new MAF.

Engine was up to proper operating temperature, and the EGR has been completely bypassed. So where to start looking? Or do I actually need to start looking anywhere - i.e., is there actually a problem? The idling speed reading is the puzzling one, but need it concern me?

[Johnny2R]

Originally Posted by Bigga

Mine did the same after a couple of weeks, had it on T4 and showed it not working, have a look at my thread "the £75 maf update." If you find out anything else with the engine causing it let me know!

I read that thread. But what you are seeing sounds to be much more obviously a problem ("working but cutting out at lower revs and not working properly"). What's the effect on the driving?

[HarryM1BYT]

Originally Posted by Johnny2R

I read that thread. But what you are seeing sounds to be much more obviously a problem ("working but cutting out at lower revs and not working properly"). What's the effect on the driving?

Terrible, I would imagine, but there might be other issues than the MAF itself causing that. Could just as easily be a bad connection in the MAF wiring. Without a thorough and proper investigation it is much to early to blame the new MAF.

[okenora]

I often get the feeling that if that insert came branded Rover instead of BMW that if it "failed" quickly the reaction would be "it can't be the MAF it's brand new" and people would go looking for the fault, but brand it BMW and it has to be the MAF alone at fault.

Other option is that MAF shop aren't supplying genuine Bosch, but that's a hard one to figure out........but put simply, genuine Bosch MAF's treated right will rarely fail quickly from new. When I was working at cars I fitted 100's of MAF's and never had a faulty one or a quick failure without some obvious cause, usually a go faster oiled filter.

[Arctic]

Originally Posted by kmtranter

I'm looking at changing the MAF Sensor and noted from harrys post its possible to change just the sensor, is the following item on ebay a worthwhile purchase
http://www.ebay.co.uk/itm/NEW-MASS-A...item20cdd21d71

Hi Kevin.
If you are going to follow the change the insert only then I think this maybe the one you are after, but I am sure someone will say if it is not
http://www.ebay.co.uk/itm/1311404965...%3AMEBIDX%3AIT

The original MAf is this one
http://www.ebay.co.uk/itm/1312772012...%3AMEBIDX%3AIT