GolfGTIforum.co.uk
Model specific boards => Golf mk4 => Topic started by: mar_k on 21 June 2012, 19:17
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I have been helping a friend with his 1.8turbo golf mk4.
He brought it round to mine as I have VAG-COM,
He had 2 lights on the dash, The emissions control light and the EPC.
I scanned the car and it showed MASS AIRFLOW SENSOR (G70) low reading,
I cleared the codes and scanned it again but the same fault was showing.
I got a new Bosch MAF and fitted it for him, then cleared the codes and both lights
went out and stayed out.
I re-scanned it and it was clear, no faults shown.
Its been running fine almost a week but now both the same lights are back on
and I scanned it again today to be greated with the above fault.
Mass airflow reading to low.
What would be causing it to knock out a new genuine Bosch MAF in just under a week?
And what does the EPC light have to do with the MAF?
any helo is appreciated
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Can happen, i went through 3 in as many months!! now nothing for about 10 months.... touch wood!
Make sure the housing is secure and its not rocking/banging around under the bay, that can make it faulty
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I really wish people would get rid of this myth that it's always the MAF.
Bosch are ISO 9001 certified, which means they have a QA system in place and use it.
They simply wouldn't have that many defective parts going out the door.
When you change the sensor and reset the codes you are resetting any learned values that the ECU has.
Thus if it's a sensor problem, it runs fine until the system re adapts to learned values. When this happens the problem returns.
It could be a wiring fault, it could be a massive leak somewhere.
If you have a poor earth, it could be causing a short.
It's not beyond the realms of possibility that you have a duff, but it's more remote that people would have you believe.
Stick a volt meter on it to see what you are getting.
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surely if the new maf went faulty in such short time you went get a replacement right.
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surely if the new maf went faulty in such short time you went get a replacement right.
Depends on why it failed, if it is faulty then yes they will replace it but if something else is causing the problem then not much chance they will help.
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I really wish people would get rid of this myth that it's always the MAF.
Bosch are ISO 9001 certified, which means they have a QA system in place and use it.
They simply wouldn't have that many defective parts going out the door.
When you change the sensor and reset the codes you are resetting any learned values that the ECU has.
Thus if it's a sensor problem, it runs fine until the system re adapts to learned values. When this happens the problem returns.
It could be a wiring fault, it could be a massive leak somewhere.
If you have a poor earth, it could be causing a short.
It's not beyond the realms of possibility that you have a duff, but it's more remote that people would have you believe.
Stick a volt meter on it to see what you are getting.
He said it was the MAF because the code it threw was Mass AirFlow reading to low. Therefore it is safe to assume its a MAF related problem, not necessarily the sensor. Not such a Myth afterall.....
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Measure the maf gs values by logging this will aid in what's the issue at hand, could be a leak that sometimes sets it off from experience, the ESP could be lighting up as of a n112 fault possibly as well. Or a short/ground issue is present.
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He said it was the MAF because the code it threw was Mass AirFlow reading to low. Therefore it is safe to assume its a MAF related problem, not necessarily the sensor. Not such a Myth afterall.....
The mere fact the problem has returned shows that changing the physical sensor did nothing.
The next logical step is not to assume the new one you've got it duff. It's that you've got the diagnosis wrong, and further investigation is required.
There was another thread recently where someone has been having issues, pulled the MAF to see if it ran worse then got it scanned. Lo and behold a MAF fault.
People pull sensors, reconnect then and then forget all the time. I've had shorts in wiring give MAF warnings before.
The fact it's thrown the same code means it probably is something on the MAF circuit, so my guess would be a harness/wiring fault.
Ideally you'd do a log of the mass flow, but short of that a voltmeter will indicate a good or bad sensor.
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I took the car to my mate who is a workshop manager at a vw dealer,
They hooked the car up to their diognostic machine and was told by his master technician that
its an air leak some where but he didn't have the time to investigate further.
We was advised to get the inlet off and replace the gasket and check all the pipes for signs of perishing,
He also said there is a 1 way vavle in a pipe on the lower part of the inlet that can often fail.
Was impressed with their machine, no wires, just a bluetooth plug that plugs into the diognostic port in the car.
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I took the car to my mate who is a workshop manager at a vw dealer,
They hooked the car up to their diognostic machine and was told by his master technician that
its an air leak some where but he didn't have the time to investigate further.
We was advised to get the inlet off and replace the gasket and check all the pipes for signs of perishing,
He also said there is a 1 way vavle in a pipe on the lower part of the inlet that can often fail.
Was impressed with their machine, no wires, just a bluetooth plug that plugs into the diognostic port in the car.
Something like this? £10 off ebay.
ebay clicky (http://www.ebay.co.uk/itm/ELM327-Car-Scanner-Bluetooth-software-OBD2-EOBD-CAN-BUS-Scanner-Tool-/180911443902?pt=UK_Diagnostic_Tools_Equipment&hash=item2a1f298fbe)
I want one. Plus an android app called Torque and you can have live logging of all sorts of data (including bhp) clipped to your dash. :smiley:
EDIT - maybe it was actually this? A bit pricier but looks more like VAG kit.
another ebay clicky (http://www.ebay.co.uk/itm/V19-VAS-5054A-SEAT-SKODA-VW-AUDI-VAG-GROUP-2012-/140781096355?pt=UK_Diagnostic_Tools_Equipment&hash=item20c7350da3)
Common MAF faults that aren't actually the MAF are (as you have found) a leak in the inlet and oil from an aftermarket filter getting on the sensor.
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well today we stripped the inlet down,
the breather that comes out the end of the inlet was perished slightly,
The ones on the bottom seem ok, not sign or perishing, no cracking or holes.
One of the injector seals was leaking aswell
We replaced the inlet gasket and all 8 of the injector seals.
I cleared the codes but they came straight back so the problem is still there.
I checked the intercooler pipes and all the other vac lines so it looks like the problem is the new Maf.
Going to go back to Euro parts with it and see what they say.
Also looking under the car I found quite a bad oil leak, Not quite sure where from as its really nasty under there,
The head is clean so its not the rocker cover gasket, Going to steam clean it and check it in a few days.
Its on the drivers side, at the rear of the engine.
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Yes mate, theres a pipe there that leaks!! U can get a new 'C' clip for it but wont last long, it wont give u any major issues, iv had a leak there since ive had the car and not cause me any grief, just knowin its there pisses me off tho
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Still no joy,
Inlet gasket replaced, injector seals replaced, all pipes check, no splits and still the car goes into limp mode
and MAF low reading fault code comes up.
Going to try another MAF sensor
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i have maf issues also :angry:
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Is it an agu? My ignition amp gave me similar faults as you've described.
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Going to try another MAF sensor
Are you using genuine MAF sensors ?
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Yes mate, theres a pipe there that leaks!! U can get a new 'C' clip for it but wont last long, it wont give u any major issues, iv had a leak there since ive had the car and not cause me any grief, just knowin its there pisses me off tho
It'll be the pipe that joins the Intercooler to the charge pipe, you can loose a massive amount of boost there so get underneath and get a strong jubilee on it, its awkward to get to, and the pipe itself is a daft design flaw, but as said you can loose lots of boost there
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Yes mate, theres a pipe there that leaks!! U can get a new 'C' clip for it but wont last long, it wont give u any major issues, iv had a leak there since ive had the car and not cause me any grief, just knowin its there pisses me off tho
It'll be the pipe that joins the Intercooler to the charge pipe, you can loose a massive amount of boost there so get underneath and get a strong jubilee on it, its awkward to get to, and the pipe itself is a daft design flaw, but as said you can loose lots of boost there
Thats the badger!!
Mar_k - Let us know if your new MAF solves it! Did you take it back to ECP, if so what did they say?
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The housing could be a Bosch item but it doesn't mean the sensor itself is. If you look inside one end you should be able to just make out BOSCH on black half of the sensor :smiley:
Do some logs with VAG COM on a full throttle 3rd gear run as golf_sib said to see what it's pulling. Limp mode should be around 100g/s max
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Wazzer have you recieved yours ok?
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Yes mate sorry should have let you know, all in and working fine :afro:
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Legend mate :cool:
Im trying to dig another out for Daz but cant seem to find one :sad:
Where do you get the tool bit to split the maf so I can take the sensor out?
Il need to put a 1.8t sensor in a vr6 housing but struggling to remove the sensor lol
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it was just a 6 point security torx bit, but the other MAF I have is a 5 point security bit which I'm struggling to find...
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Awsome I may just remove them and change them so I can use something easier :smiley:
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I thinks my MAF may not be good enough for my ko3s turbo I heard you can straight swap an RS4 MAF can someone help please?
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Yes its a genuine Bosch MAF,
It was in a security sealed bosch box. Will do some logs and post up the results.
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I thinks my MAF may not be good enough for my ko3s turbo I heard you can straight swap an RS4 MAF can someone help please?
rubbish