Calling All MAFs

[Andrew J]

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 ! 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.

 

[Mike6]

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

 

[Andrew J]

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.

 

[colb]

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]

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.

 

[Andrew J]

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.

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?

 

[enuff_zed]

My dipstick is super tight

Permission to steal your chat up line? :rofl:

 

[Andrew J]

My dipstick is super tight

Permission to steal your chat up line? :rofl:

:rofl: permission granted. Better yet, stick it in your signature :lol:

 

[Andrew J]

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?

 

[PDJ]

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

 

[Andrew J]

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?

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.

 

[Andrew J]

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.

 

[Reamesy]

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

https://youtu.be/BwoRCM-jIbg?si=A6iY88_QZSD2Jsy2

 

[PDJ]

JC Racing in Thirsk

Yes my mistake it is just behind a police garage near the race course

https://www.jcracing.info

 

[Andrew J]

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.

 

[j3nks79]

£48 is very reasonable.

 

[Andrew J]

Just to confirm, the £48 was for half and hour and pre vat. £115/hr seemed quite a lot for a diagnostic/smoke testing.

 

[Andrew J]

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.

I managed to get some live data whilst driving recently. The MAF is just not reading by the looks of it. Can see even under load there's no signal back to the ecu. Is this the nail in the coffin for a faulty MAF giving me the P0102 code? I'm still knocking together a smoke machine to test at the weekend but just wondered if this is curtains for the MAF?

 

[colb]

Certainly looks like the Maf is dead from your screen shot, no movement at all. If you unplug its electrical connector it will go into default settings and run better albeit the Maf signal won't be generated so you can't view it. If the Maf is the cause the engine control module will be affected and cause havoc with fuel trims as it tries to get the mixture right. Often it will see what it thinks is a lean mixture usually from air leaks entering past the Maf and not being measured so increases fuel at the injectors to richen what it thinks is a lean condition, it will continue to do this until its putting 20% more fuel in before it realises something is amiss and sets the engine management light to draw attention to the fault. Bad Maf will also cause the same issue. To me it looks like your fuel trims are in the minus which means its actually taking fuel away as it thinks its running rich probably as a result of the absence of any reading from the Maf. If you are going to replace the Maf only fit oem Bosch or Siemens brands don't buy cheap ones they seldom work or last long if they do. Do continue with your smoke machine, mine has proved invaluable for my cars and other members cars I have smoked, finding leaks is very easy with smoke. Ideally the trims should be around 0% or up to around 5% across the performance range.

 

[Andrew J]

Read the codes today with my friends AA set up (what a piece of kit that was). I got a 2783 code which is faulty maf sensor. Unplugging it confirmed it went to open circuit which shows the wiring is at least not shorting out. It would give a reading of 0.41 kg/h with idle supposed to be between 5-25kg/h (if my memory serves me correctly). I can't find a bosch maf anywhere but can see a VDO one on autodoc for £195 (https://www.autodoc.co.uk/vdo/1736813#mass-air-flow-sensor). I believe Siemens owns VDO? Is there an alternative ego for boach aswell?