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Calling All MAFs

Discuss problems you have had or are having with your Z4
Andrew J
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Calling All MAFs

Post by Andrew J » Sun Mar 24, 2024 8:55 pm

I've had a P0102 code since I bought the car and I thought this might be down to air leaks. Investigated and low and behold... a split air inlet boot and a rocker cover gasket leak. Both are now rectified but I'm still getting the dreaded P0102! I did have P0174 & P0171 codes however joth ha e now disappeared. My OBD reader is also saying I'm only getting 0.1 g/s regardless of revs which is making me now suspect the MAF is at fault. I unplugged the MAF and then it goes to 0 showing that its at least getting (some) power. Is this indicative of a kaput MAF?

I've looked for the price for a BMW MAF and :o! Is there an equivalent aftermarket oem from automotive that's a good replacement? Or does anyone local to Teesaide have a known working spare MAF lying around that I could swap in to rule out a dodgy MAF.

Thanks in advance for any help around the subject.
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Calling All MAFs

Post by Mike6 » Mon Mar 25, 2024 7:14 pm

Looking at replacing the MAF on my 2.5 SE as well and they vary in price a lot. I was told a good all rounder is available from Autodoc and is the Ridex 3926AO220. Costs about £52. Will depend on what model car you have. Hope this helps

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Calling All MAFs

Post by Andrew J » Tue Mar 26, 2024 11:57 pm

Mike6 wrote: Mon Mar 25, 2024 7:14 pm Looking at replacing the MAF on my 2.5 SE as well and they vary in price a lot. I was told a good all rounder is available from Autodoc and is the Ridex 3926AO220. Costs about £52. Will depend on what model car you have. Hope this helps
I've got the 3.0i and I saw the ridex one too but have seen a lot of posts saying down go cheap on the maf, it'll only lead to worse issues down the road.

I had my first drive out today and it seemed fine but wouldn't heel and toe. When I got back P0102 still present :(. MPG was 33.7 on a 30 me journey sat at 70 mph for the majority which i disnt think was too bad considering it might well just be running of the DME tables. The maf is still reading 0.1g/s but I didn't managed to get any online fuel trims. When it was stationary there was an 18% fuel trim on both banks. Is this normal for idle? I would say it wasn't fully up to temperature. Is there a method to check my maf with a multimeter to rule it out? It would be good to rule it out so I at least know its probably an air leak that I need to chase down.
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Calling All MAFs

Post by colb » Wed Apr 03, 2024 7:58 am

In my experience a Maf either works or it doesn't replacement with oem brands Bosch or Seimens do not buy cheap replacements, they don't work and don't last long if they do have been down that route myself.
Fuel trims being high is a good indication of either air leaks or bad Maf. Do a smoke test to rule out any air leaks you haven't found so far then change the Maf and view the fuel trims with a decent scanner to see if they have reduced and back in spec. Do check the rear underside edge of the inlet manifold for missing rubber blanking caps that seal off some unused air ports, these do perish and fall off and go unnoticed unless a smoke test reveals them. There is also a rubber O ring in the dipstick tube if you have one and that can be a cause of air leaks.
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Calling All MAFs

Post by Z4Mariner » Wed Apr 03, 2024 1:38 pm

Hi Andrew J - Plus one on what Colb said!

Do you have an M54 engine (pre-LCI)? My E86 has an N52, but I had an M54 in an E46. There are many possibilities for vacuum leaks, and the possibilities will all become realities with age.

If you cannot smoke test, then carefully use a mirror to confirm blanking caps at rear underside of manifold - that they are there, AND that they are not cracked. If your car has supplemental air injection (SAI) and exhaust gas recirculation (EGR), and the hose to the valve fails, you usually will get a separate code for SAI - but check that hose anyway. That hose runs along the block and gets cooked. Also check the valve that attaches that hose at the manifold rear underside - if the valve is leaky or connections are loose, it can be a leak point. Additionaly there are the idle control valve grommet, throttle body gasket, DISA seal, CCV (PCV) oil separator system, and the brake booster and grommet.

I went through all the above on my E46 before I found a bad dipstick O-ring like Colb mentioned. That leak was very hard to find, because it never set a code, but produced a surging cold idle until the engine oil warmed up and 'sealed' the leak

If you can find a fellow Zed owner close by, have them walk through all this with you. You'll get it solved - it's just about patiently walking through all the possibilities.
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Andrew J
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Calling All MAFs

Post by Andrew J » Thu Apr 04, 2024 9:39 am

colb wrote: Wed Apr 03, 2024 7:58 am In my experience a Maf either works or it doesn't replacement with oem brands Bosch or Seimens do not buy cheap replacements, they don't work and don't last long if they do have been down that route myself.
Fuel trims being high is a good indication of either air leaks or bad Maf. Do a smoke test to rule out any air leaks you haven't found so far then change the Maf and view the fuel trims with a decent scanner to see if they have reduced and back in spec. Do check the rear underside edge of the inlet manifold for missing rubber blanking caps that seal off some unused air ports, these do perish and fall off and go unnoticed unless a smoke test reveals them. There is also a rubber O ring in the dipstick tube if you have one and that can be a cause of air leaks.
Z4Mariner wrote: Wed Apr 03, 2024 1:38 pm Hi Andrew J - Plus one on what Colb said!

Do you have an M54 engine (pre-LCI)? My E86 has an N52, but I had an M54 in an E46. There are many possibilities for vacuum leaks, and the possibilities will all become realities with age.

If you cannot smoke test, then carefully use a mirror to confirm blanking caps at rear underside of manifold - that they are there, AND that they are not cracked. If your car has supplemental air injection (SAI) and exhaust gas recirculation (EGR), and the hose to the valve fails, you usually will get a separate code for SAI - but check that hose anyway. That hose runs along the block and gets cooked. Also check the valve that attaches that hose at the manifold rear underside - if the valve is leaky or connections are loose, it can be a leak point. Additionaly there are the idle control valve grommet, throttle body gasket, DISA seal, CCV (PCV) oil separator system, and the brake booster and grommet.

I went through all the above on my E46 before I found a bad dipstick O-ring like Colb mentioned. That leak was very hard to find, because it never set a code, but produced a surging cold idle until the engine oil warmed up and 'sealed' the leak

If you can find a fellow Zed owner close by, have them walk through all this with you. You'll get it solved - it's just about patiently walking through all the possibilities.
Thanks for the response folks. I did try and feel around under the manifold whilst I was rebuilding the disa and couldn't feel any free apertures but will have a better look at the weekend. My dipstick is super tight so I suspect this might not be the cause but will look into a new o ring anyway, may as well rule it out for £1 o ring for the peace of mind. A good scanner is certainly one thing I need. C310+ seem to be a popular choice? Does this show live data and store it? I like the functionality of torque light where you can see what's happening but I can't believe that a free app is that good at removing persistent codes.

I've replaced the inlet boot which was split and that has cured the P0171 & P0174 codes. Getting a smoke test might prove tricky as I've never heard of anyone doing one here. Not to say ita not possible, just need to find somewhere that can do it. Mine doesn't have the secondary air pump nor EGR so the hose that runs along the block shouldn't be there.

Oh and @Z4mariner, completely off topic, I see you are minnesota based, a fellow vikings fan I presume?
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Calling All MAFs

Post by enuff_zed » Thu Apr 04, 2024 10:25 am

Andrew J wrote: Thu Apr 04, 2024 9:39 am My dipstick is super tight
Permission to steal your chat up line? :rofl:
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Calling All MAFs

Post by Andrew J » Thu Apr 04, 2024 10:55 am

enuff_zed wrote: Thu Apr 04, 2024 10:25 am
Andrew J wrote: Thu Apr 04, 2024 9:39 am My dipstick is super tight
Permission to steal your chat up line? :rofl:
:rofl: permission granted. Better yet, stick it in your signature :thumbsup: :lol:
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Calling All MAFs

Post by Andrew J » Sat Apr 06, 2024 9:53 am

I've just read somewhere that when you press the brakes and the revs rise, this could be a sign of a failing(ed) maf. Is this correct? I have to be careful how much I press the brake at traffic lights as my revs do rise and I don't want it to like I'm setting up launch control :lol: .

Edit: thinking about it, it's probably an air leak needing more vacuum for the brakes. Will put more effort into finding somewhere that can do a smoke test. Anybody know anywhere in the North East (preferably teeside) that does it?
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Calling All MAFs

Post by PDJ » Sat Apr 06, 2024 6:11 pm

Andrew J wrote: Sat Apr 06, 2024 9:53 am Edit: thinking about it, it's probably an air leak needing more vacuum for the brakes. Will put more effort into finding somewhere that can do a smoke test. Anybody know anywhere in the North East (preferably teeside) that does it?
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Post by Andrew J » Sat Apr 06, 2024 6:21 pm

colb wrote: Wed Apr 03, 2024 7:58 am There is also a rubber O ring in the dipstick tube if you have one and that can be a cause of air leaks.
Was this the o ring of the actual dipstick or the o ring at the bottom of the tube that goes into the oil pan?
PDJ wrote: Sat Apr 06, 2024 6:11 pm
Andrew J wrote: Sat Apr 06, 2024 9:53 am Edit: thinking about it, it's probably an air leak needing more vacuum for the brakes. Will put more effort into finding somewhere that can do a smoke test. Anybody know anywhere in the North East (preferably teeside) that does it?
JC Racing in Darlington
Thanks PDJ. Will give them a call on Monday.
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Post by Andrew J » Sat Apr 06, 2024 6:52 pm

PDJ wrote: Sat Apr 06, 2024 6:11 pm
Andrew J wrote: Sat Apr 06, 2024 9:53 am Edit: thinking about it, it's probably an air leak needing more vacuum for the brakes. Will put more effort into finding somewhere that can do a smoke test. Anybody know anywhere in the North East (preferably teeside) that does it?
JC Racing in Darlington
Just googled and could only find JCTuning in darlington. Is this who you meant? I wouldn't normally ask as the name is very close but there's a JC Racing in Thirsk so just wanted to make sure.
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Calling All MAFs

Post by Reamesy » Sat Apr 06, 2024 7:52 pm

Watch this video. Great learning about using OBD and testing to confirm the faulty components.

https://youtu.be/BwoRCM-jIbg?si=A6iY88_QZSD2Jsy2
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Post by PDJ » Sun Apr 07, 2024 10:07 pm

Andrew J wrote: Sat Apr 06, 2024 6:52 pm JC Racing in Thirsk
Yes my mistake it is just behind a police garage near the race course

https://www.jcracing.info

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Post by Andrew J » Mon Apr 08, 2024 10:54 am

PDJ wrote: Sun Apr 07, 2024 10:07 pm
Andrew J wrote: Sat Apr 06, 2024 6:52 pm JC Racing in Thirsk
Yes my mistake it is just behind a police garage near the race course

https://www.jcracing.info
I called up JCracing and they don't have a smoke tester. The chap I spoke to said they haven't really used one but there is another garage in Thirsk that they've sent stuff to for air leak checking (I disnt quite get the name of it over the phone). He also said they only really deal with the oily bits on race cars and tend not to do road cars that much. Seemed a nice guy though👍🏻. In case anyone needs a smoke test doing Sterling services in stockton do smoke test. They are charging £48 but they've called it a diagnostic so I guess they'll read the codes as well (although I already know the bloody code that's driving me bonkers lol). Does £48 sound reasonable for a smoke test? I thought it was a bit steep to be honest.
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