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Discussion Starter · #1 ·
Hi all, sorry for more questions. I've done a search but can't find the answers, just wondering what average MPG people are getting from their 320 CI's?
I've been getting 23 to 24 around the doors, had to travel to Leeds today from Durham and only returned 26.5 which I thought could be more considering was at steady 70ish there and back. I have got a problem of the revs rising and falling on their own mainly between 2-3k revs, which after a diagnostic (no fault codes found) and speaking to several people in the know (I'm in the motor trade) I think I've narrowed down to a non retrun valve in which apparently the diaphram perishes. Which leads to my second question, where the hell is it:embarrassed
I've had the car on my mates ramp, looked underneath on top everywhere, even taking off the maf sensor and air intake assembly but still can't find it. My mate had a 318 in at the time and it was just above the inlet manifold on that. It's part number six in the link below.

http://www.realoem.com/bmw/showparts.do?model=BN12&mospid=47615&btnr=11_2203&hg=11&fg=45

Sorry for the long post but I'm lost and looking for inspiration:D
 

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Discussion Starter · #3 ·
Hi,

Idle control would only affect when engine idling. One of our customers is a BMW dealership, the parts manager asked the workshop lads what they thought it could be and they said the non return valve, also one of our indpendent garage customers has changed a few, he also a mate who works for BMW and he said 90% sure it would be that aswell. Thing is the valve won't return a fault code whereas sensors, idle control etc will. I've had three different diagnostic machines on it that range in price from £2.5k to £13 all with BMW dealer level access and none have returned a fault code apart from a misfire that a new coil sorted:thumbsup
 

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Discussion Starter · #4 ·
Should add, I know its somewhere around the inlet manifold but not sure exactly where, I'm assuming underneath hidden from view:confused
 

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Should add, I know its somewhere around the inlet manifold but not sure exactly where, I'm assuming underneath hidden from view :confused
Yes, it is located under the inlet manifold on the right hand side. It will be half black, half white indicating it's direction to fit, so note which end connects to which pipe. Back to my original question...if revs are not fluctuating on idle, does that mean they are when you are driving?
 

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Discussion Starter · #6 ·
Yes, it is located under the inlet manifold on the right hand side. It will be half black, half white indicating it's direction to fit, so note which end connects to which pipe. Back to my original question...if revs are not fluctuating on idle, does that mean they are when you are driving?
Yes sorry didn't realise what you meant. The car seems to idle perfectly, but go to pull away at say 1.5k-2k and the revs will rise on their own then suddenly drop to say 500. Also when driving, for instance 5th gear between 2k-3k you can feel the car surging then backing off if that makes sense:confused
Have to say I love everything else about the car but this is at best, ruining the driving pleasure and worst dangerous if pulling away from a junction and suddenly the revs drop. Beginning to wish I'd bought another Impreza:frown
 

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Discussion Starter · #7 ·
Forgot to ask, do you need to remove the inlet manifold to get to it or is there a knack to accessing it, thanks for your help Neal, was beginning to think I was imagining this valve:thumbsup
 

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Yes sorry didn't realise what you meant. The car seems to idle perfectly, but go to pull away at say 1.5k-2k and the revs will rise on their own then suddenly drop to say 500. Also when driving, for instance 5th gear between 2k-3k you can feel the car surging then backing off if that makes sense:confused
Have to say I love everything else about the car but this is at best, ruining the driving pleasure and worst dangerous if pulling away from a junction and suddenly the revs drop. Beginning to wish I'd bought another Impreza:frown
Mine does the same......and get About 20-22mpg round town...smoking a bit at idle recently..
nothing but greif with this car...changed cam sensor twice...breather pipes...purge valve....i'm changing a coil pack tomorrow as getting an intemittant missfire fault code...dont think its gonna help tho???? also get to lean fault codes all the time & occasional too rich ????
 

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Discussion Starter · #9 ·
Mine does the same......and get About 20-22mpg round town...smoking a bit at idle recently..
nothing but greif with this car...changed cam sensor twice...breather pipes...purge valve....i'm changing a coil pack tomorrow as getting an intemittant missfire fault code...dont think its gonna help tho???? also get to lean fault codes all the time & occasional too rich ????
All the symptons of mine and yours sound like vanos unit seal failure but I'm told by at least 3 people that these will throw up a fault code. Thing is if something is working within tolerance how can it, plus the vanos is mechanical from my knowledge, I know there are sensors attached but surely none of these would pick up data telling you a seal is worn? I Don't know what to believe anymore, my first experience of BMW is not a pleasant one at the minute, anyone want to buy a cheap Coupe:frown
 

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:sarcastic:sarcastic Dazh66 and coolhandlluke your not alone..........must be a 320 thing!!!

I have a similar problem with poor mpg, revs at standstill wander up and down...occassional surge in power....cuts out sometimes on pull away / reverse:eek

Dont really know where to start...CDV, O2 sens, camshaft sens, MAF sens, crankshaft sens.......no fault codes also so its a real pain in the arse to pinpoint.
 

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Discussion Starter · #11 ·
Right, going to one of my customers tomorrow who specialises in BMW's and Ferrari's:D So at worst I'll get to lust over some Italian machinery. Got a boot full of sensors from work just in case it turns out one has an intermmitent fault, just hoping by lunchtime it's up and running normally, fingers crossed:thumbsup
 

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Seem to be getting about 26mpg at the moment, although I am driving it like an old man! Would of at least thought I would of got 35 or so..... its costing me a fortune!
 

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Discussion Starter · #15 ·
Just a quick update, got the diagnostic this morning, came up showing that temp sensor in radiator hose reading -48 degrees and can data fault from dme/dde which is basically that the connection between the DSC and ECU has a fault. Got a temp sensor from work so will plug that in when the car has cooled enough and will ring the lads at BMW monday to see if they have any ideas on the other fault. Having said that, while he had the unit plugged in he reset the throttle adaptions back to the BMW settings and so far I've done about 30 miles with DSC switched on and off and the car has driven perfect:hihi:thumbsup
If anyone local to me needs theirs looking at I'll PM his number, as hereally knows his stuff, he's based in Crook:thumbsup
 

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There is a known problem on some e46 models with the wiring from the throttle body, it is listed on Autodata IIRC so have a look if you have access to it or one of your friends :thumbsup
 

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Just a quick update, got the diagnostic this morning, came up showing that temp sensor in radiator hose reading -48 degrees and can data fault from dme/dde which is basically that the connection between the DSC and ECU has a fault. Got a temp sensor from work so will plug that in when the car has cooled enough and will ring the lads at BMW monday to see if they have any ideas on the other fault. Having said that, while he had the unit plugged in he reset the throttle adaptions back to the BMW settings and so far I've done about 30 miles with DSC switched on and off and the car has driven perfect:hihi:thumbsup
If anyone local to me needs theirs looking at I'll PM his number, as hereally knows his stuff, he's based in Crook:thumbsup
I changed my radiator hose temp switch for the same reason ..reading -48 degrees....it made no difference at all...apparently that sensor is just for the aircon..and mine has always worked fine.
 

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in heavy traffic you wont get much more than that in town ,take it for a run on motorway see how much you get reset the mpg
 
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