540i running problem

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   Have an issue with a slight hesitance in the rev range when acceleration through the gears for some time now, but it seems to go away, but again is definately back!
The issue is if I gun through the gears and usually in third as the engine approaches 4k revs there is a slight hesitation, not quite a misfire but a definate momentry hold back, its over as quick as it appeared and unless you get back to the same rev range it is fine in all other area`s??  my code reader is quite good and looks at scores of things, it came up with some old codes relating to the O2 sensors left bank 1 no activity? however reset and no return
I am wondering if the variable valve timing (vanos) operates around this rev range? or can a cam sensor cause this but not show a fault code.
Had a recent full fluids and filters service, new BMW plugs fuel and air filters etc.
Its a real shame as the car runs tip top other than this with good mpg and performance to boot.
Any help or advise /tips on what else to check. 
Jeff TT

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Jeff TT Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Groupie Joined: 20-August-2004 Location: United Kingdom Status: Offline Points: 93	Post Options Post Reply Quote Jeff TT Report Post Thanks(0) Quote Reply Topic: 540i running problem Posted: 01-November-2010 at 23:04
	Have an issue with a slight hesitance in the rev range when acceleration through the gears for some time now, but it seems to go away, but again is definately back! The issue is if I gun through the gears and usually in third as the engine approaches 4k revs there is a slight hesitation, not quite a misfire but a definate momentry hold back, its over as quick as it appeared and unless you get back to the same rev range it is fine in all other area`s?? my code reader is quite good and looks at scores of things, it came up with some old codes relating to the O2 sensors left bank 1 no activity? however reset and no return I am wondering if the variable valve timing (vanos) operates around this rev range? or can a cam sensor cause this but not show a fault code. Had a recent full fluids and filters service, new BMW plugs fuel and air filters etc. Its a real shame as the car runs tip top other than this with good mpg and performance to boot. Any help or advise /tips on what else to check. Jeff TT


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Andrew Rolland Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Go away rain Joined: 19-August-2004 Location: Scotland Status: Offline Points: 6579	Post Options Post Reply Quote Andrew Rolland Report Post Thanks(0) Quote Reply Posted: 02-November-2010 at 13:01
	If there are no codes being thrown up then it's a nightmare. What about air leaks in and around the inlet manifold/air box? Mike, with an E34 540 is also suffering a very similar sounding problem, he reckons it is related to a missaligned crankshaft pulley. I've also got a very very occasional splutter too, at 1,500 rpm but I'm not convinced completely that it is what I thought it was (torque converter lock up clutch) and I'm now thinking something on the ignition side. I'm not convinced that when a component is failing it will log a diagnostic fault until it faults to a certain level. Until it goes completely I'm thinking it won't register a problem, meaning that problems like these could be chuffin' anything and are a real headache to sort out. Some of your comments relate to this too. Other than that, dirty fuel/supermarket fuel? Coil breaking down? HTH Andrew
	Be exclusive and drive a Petrol 5 Series! Current '13 62 F10 535i MSport Auto Previous '04 04 E60 545i SE Auto '03 53 E60 545i SE Auto (Stolen) '98 S E39 523i SE Auto

Crispy-d Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member I Joined: 07-May-2008 Location: Ipswich/Bristol Status: Offline Points: 130	Post Options Post Reply Quote Crispy-d Report Post Thanks(0) Quote Reply Posted: 02-November-2010 at 18:53
	If it's rev-related then this could point towards a sensor operated problem/restriction as it's usually 4000rpm that's used as a limit I believe (Revving in neutral, 'limp home mode' in some cars, when there's an ignition fault, etc). But you say you can get past 4k, it's just there's a slight hesitation. It could even be a knock sensor - these were prone to cracking on my last car but I've never heard of one going on a BMW yet! If the power is back up to normal at higher revs then it's unlikely to be this, but could it be there is a fuel delivery problem such as a dicky fuel pump or even just a clogged fuel filter? I'm sure I read somewhere a suggestion about there being a potential resonant frequency at those sort of revs so that if a sensor was a little iffy then at those particular revs the vibration could be enough to cause a poor reading of either the camshaft or crankshaft sensor (relating to what's been said about Mike's problem). Definitely worth checking as many connectors as you can and also checking the coils and to see if there's oil on the coil boots. Mine are shot to pieces now and although it's not missing it's definitely not as smooth as I think it could be.
	BMW E39 M5 - 2002 Land Rover 110 4.0 V8 - 1986 BMW E39 530d Manual SE - 2001 BMW E34 540i 6 Speed Manual - 1995 Volvo S90 3.0 CD - 1997 Volvo 460 Si Turbo - 1995 Volvo 340 GL - 1989