N52 - Drives better without MAF but still not great
Discussion
Ed.Neumann said:
E82_125i said:
Ive ordered a used MAF for my exact model off eBay that was cheap as im not one hundred percent convinced it is the MAF.
That could just confuse matters even more. New, OEM (as Sam said above, Siemens VDO), is the only way really
It's worth bearing in mind that just because the car works better with the MAF disconnected doesn't always mean that the MAF is the source of the fault. As noted in a post above, disconnecting the MAF forces the ECU to use some fixed compensation tables instead of dynamically adjusting based on the actual airflow as measured by the MAF. This can mean that issues like air leaks are no longer causing incorrect air mass measurements, as the air mass is no longer measured.
Years back when I had an E46 330Ci it wasn't running quite right and would improve with the MAF disconnected. It would be the obvious solution to replace the MAF but in this instance it wouldn't have helped, the problem turned out to be a split in the intake boot after the MAF that was only visible after removing it. £25 or so later and the car ran perfectly on the original MAF.
I'm not saying the MAF isn't the issue here, it might be but equally it might not. Unplugging the MAF doesn't really help to determine whether the MAF is at fault as there are too many other factors that are changed by the ECU when you unplug the MAF.
Years back when I had an E46 330Ci it wasn't running quite right and would improve with the MAF disconnected. It would be the obvious solution to replace the MAF but in this instance it wouldn't have helped, the problem turned out to be a split in the intake boot after the MAF that was only visible after removing it. £25 or so later and the car ran perfectly on the original MAF.
I'm not saying the MAF isn't the issue here, it might be but equally it might not. Unplugging the MAF doesn't really help to determine whether the MAF is at fault as there are too many other factors that are changed by the ECU when you unplug the MAF.
pmorg4 said:
It's worth bearing in mind that just because the car works better with the MAF disconnected doesn't always mean that the MAF is the source of the fault. As noted in a post above, disconnecting the MAF forces the ECU to use some fixed compensation tables instead of dynamically adjusting based on the actual airflow as measured by the MAF. This can mean that issues like air leaks are no longer causing incorrect air mass measurements, as the air mass is no longer measured.
Years back when I had an E46 330Ci it wasn't running quite right and would improve with the MAF disconnected. It would be the obvious solution to replace the MAF but in this instance it wouldn't have helped, the problem turned out to be a split in the intake boot after the MAF that was only visible after removing it. £25 or so later and the car ran perfectly on the original MAF.
I'm not saying the MAF isn't the issue here, it might be but equally it might not. Unplugging the MAF doesn't really help to determine whether the MAF is at fault as there are too many other factors that are changed by the ECU when you unplug the MAF.
My exact thoughts too - thats why despite everyone saying just go ahead and get the MAF, i am still hesitant to spend a good chuck of money on a part that i cant return and may not make a difference. I have the used MAF and annoyingly (but predictably) it throws a fault code but the ECU recognises it and it does still feel smoother...maybe even smoother than with it unplugged. Thought itd be worth a try for £19.Years back when I had an E46 330Ci it wasn't running quite right and would improve with the MAF disconnected. It would be the obvious solution to replace the MAF but in this instance it wouldn't have helped, the problem turned out to be a split in the intake boot after the MAF that was only visible after removing it. £25 or so later and the car ran perfectly on the original MAF.
I'm not saying the MAF isn't the issue here, it might be but equally it might not. Unplugging the MAF doesn't really help to determine whether the MAF is at fault as there are too many other factors that are changed by the ECU when you unplug the MAF.
So i have removed the intake boots and and anything after the MAF and all looks fine, ive also sprayed brake cleaner spray around it as suggested and no signs of the idle moving.
The only other thing i presume can cause this is if the DISA valves or manifold gaskets are leaking air but not sure if this would be enough to make it feel sluggish. Last time i pulled the disa it looked quite new still.
I do have a leak from my valvetronic motor gasket but specialist garages have advised that this shouldnt cause performance issues. By watching fuel trims on my car it also seems to run rich, not lean (positive fuel trims) so i guess that rules out an air leak?
Yup... But after being there / doing that with a previous M54 E39 and replacing intake boots, rebuilding the DISA, new vac lines and vac bung etc...
It was still a new MAF that sorted it...
I get starting cheap and working from there...
But these issues all scream MAF to me unfortunately
It was still a new MAF that sorted it...
I get starting cheap and working from there...
But these issues all scream MAF to me unfortunately
d_a_n1979 said:
Yup... But after being there / doing that with a previous M54 E39 and replacing intake boots, rebuilding the DISA, new vac lines and vac bung etc...
It was still a new MAF that sorted it...
I get starting cheap and working from there...
But these issues all scream MAF to me unfortunately
Just a thought - alternatively could this be a fuelling issue? And would have thought any considerable air leak would show as an error code anywayIt was still a new MAF that sorted it...
I get starting cheap and working from there...
But these issues all scream MAF to me unfortunately
Again no signs but i just want to rule out as much as i can before i fire away on the MAF. Im just thinking along the lines of injectors, cats, fuel pumps. Would unplugging a MAF override any of these if the components were failing.
My old maf doesnt show any signs of less voltage or any weird readings etc - thats why im doubtful as usually people report low or no voltage and less air being read through diagnostics when its dying. For £120 i do think its worth a punt (some garages charge £80 for diagnostics alone!) But i know ill be even closer to giving up on the car if it doesnt work as im all out of ideas.
E82_125i said:
d_a_n1979 said:
Yup... But after being there / doing that with a previous M54 E39 and replacing intake boots, rebuilding the DISA, new vac lines and vac bung etc...
It was still a new MAF that sorted it...
I get starting cheap and working from there...
But these issues all scream MAF to me unfortunately
Just a thought - alternatively could this be a fuelling issue? And would have thought any considerable air leak would show as an error code anywayIt was still a new MAF that sorted it...
I get starting cheap and working from there...
But these issues all scream MAF to me unfortunately
Again no signs but i just want to rule out as much as i can before i fire away on the MAF. Im just thinking along the lines of injectors, cats, fuel pumps. Would unplugging a MAF override any of these if the components were failing.
My old maf doesnt show any signs of less voltage or any weird readings etc - thats why im doubtful as usually people report low or no voltage and less air being read through diagnostics when its dying. For £120 i do think its worth a punt (some garages charge £80 for diagnostics alone!) But i know ill be even closer to giving up on the car if it doesnt work as im all out of ideas.
Simply learnt what was going on through experience and generally those parts were the first parts I alwasy replaced when I bought another E39 530i etc
d_a_n1979 said:
Nope not necessarily; I've had MAF fails before, no codes. Torn intake boots, car running lean etc; generic codes...
Simply learnt what was going on through experience and generally those parts were the first parts I alwasy replaced when I bought another E39 530i etc
Just an update on this. Was on the verge on ordering a MAF but was not 100% convinced as it was displaying correct voltage and 3.50g/s at idle on my diagnostics which is supposedly what it should read. The car also now seems to feel a bit sluggish with the MAF unplugged.Simply learnt what was going on through experience and generally those parts were the first parts I alwasy replaced when I bought another E39 530i etc
To be on the safe side i performed a smoke test on the engine using a DIY method. I have interestingly but equally as annoyingly found a leak coming from down the side of one of my spark plug tubes on the engine cover. I wonder if im looking at a cracked valve cover, i cannot see exactly where its coming from but at least i have found something that may help pinpoint what is going on here.
Photo below of where the smoke was emitting from.
Catatafish said:
Looks like oil is weeping out of the seal from the steptronic motor above as well. That is a common failure and quite easy to change the gasket.
Yes ive had that for a while annoyingly! It stinks when the oil seeps out and hits the exhaust shield. I think if the whole valve cover needs doing then i might aswell leave the gasket until thats replaced with it.Gassing Station | BMW General | Top of Page | What's New | My Stuff