Replacing an Air Flow Meter
Moderator: martauto
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billy
- E30 Zone Newbie

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Hi there abody
I have just bought a second hand air flow meter (from ebay) for my 325i cab (surging engine)
Is replacing the unit a job I can tackle myself or do I have to take out a 10 year loan and put it in for professional doctoring?
I have just bought a second hand air flow meter (from ebay) for my 325i cab (surging engine)
Is replacing the unit a job I can tackle myself or do I have to take out a 10 year loan and put it in for professional doctoring?
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Widge
- E30 Zone Addict

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It's a two 10mm nut and one electrical connector job...... I'm sure you can manage that, no matter how clumsy with a spanner you make your self out to be 
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garyp_E30_325i
- E30 Zone Regular

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- Location: Sunny (I wish!) Glasgow
Nah, it's really easy, you can see everything you need to undo, there's nothing nasty hidden away waiting to cause you grief. A 30min job.
From memory it bolts to a bracket in the engine bay, there's one electrical connection, the rubber boot to the throttle body is just a jubilee clip and the air box, that's it...
Though while you are there you should consider binning the restrictive airbox/filter for a cold air system (cone filter on its own is no good, draws in hot air from the engine).
From memory it bolts to a bracket in the engine bay, there's one electrical connection, the rubber boot to the throttle body is just a jubilee clip and the air box, that's it...
Though while you are there you should consider binning the restrictive airbox/filter for a cold air system (cone filter on its own is no good, draws in hot air from the engine).
'89 325i - was an SE but not anymore, was bronze-beige metallic (yeuch!) but now techno-violet (thankfully)
'89 Toyota Corolla GTi-16 - track, hillclimb & sprint car (yeeha!)
'08 Buell XB12Ss - American engineering at it's 'best'... good fun though
'89 Toyota Corolla GTi-16 - track, hillclimb & sprint car (yeeha!)
'08 Buell XB12Ss - American engineering at it's 'best'... good fun though
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Brianmoooore
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Standard airbox and (clean) filter is more than adequate for an unmodified or lightly modded engine, and, unlike cone filters, actually filters the airgaryp_E30_325i wrote: Though while you are there you should consider binning the restrictive airbox/filter
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billy
- E30 Zone Newbie

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Thanks for the advice, I have no mechanical knowledge at all but that disnae mean that I dont like e 30,s I just dont have the time to get my fingers oily on a regular basis like most guy's.
This is my third E 30, (on the trot) 1st was a 320 se coupe that set off the love affair and gave me the bug. I think it was the first time I came off a roundabout just after a long dry spell and then a summer shower "you know what I mean the control, the poise, the AUDIENCE well after gliding up the road sideways for 100 yards under full control and that was me hooked.
My latest is a 325i 1988 cab 27,000 miles "yes thats 27,000 miles" in lachs silver and one Titled Owner It is totaly standard and therefore I wont be modding the airbox/filter "but thanks for the advice" the car has a few wee scratches but absolutly no rust whatsoever "not even at the rear number plate light" the scratches were probably caused by Sir *** ****** moving the antiques around the collectors cars in the garage. however ta for taking time to reply and unfortunately because I am a total thickhead wee mechanics you will probably all hear from me again.
This is my third E 30, (on the trot) 1st was a 320 se coupe that set off the love affair and gave me the bug. I think it was the first time I came off a roundabout just after a long dry spell and then a summer shower "you know what I mean the control, the poise, the AUDIENCE well after gliding up the road sideways for 100 yards under full control and that was me hooked.
My latest is a 325i 1988 cab 27,000 miles "yes thats 27,000 miles" in lachs silver and one Titled Owner It is totaly standard and therefore I wont be modding the airbox/filter "but thanks for the advice" the car has a few wee scratches but absolutly no rust whatsoever "not even at the rear number plate light" the scratches were probably caused by Sir *** ****** moving the antiques around the collectors cars in the garage. however ta for taking time to reply and unfortunately because I am a total thickhead wee mechanics you will probably all hear from me again.
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Brianmoooore
- E30 Zone Team Member

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Only things that could go wrong that I can think of, is the rubber block thet the airfilter case sits on can fall off, and the big rubber air hose may split if it's perished and cracked already.
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DaveD
- E30Zone Wiki Specialist
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- Location: Sheffield
you mentioned surging engine ...have you cleaned you ICV ?? that can cause engine surgebilly wrote:Hi there abody
I have just bought a second hand air flow meter (from ebay) for my 325i cab (surging engine)
Is replacing the unit a job I can tackle myself or do I have to take out a 10 year loan and put it in for professional doctoring?
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billy
- E30 Zone Newbie

- Posts: 4
- Joined: Fri Mar 25, 2005 11:00 pm
Thanks Brian I will watch for that
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garyp_E30_325i
- E30 Zone Regular

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I just replaced the rubber boot between the AFM & throttle body, cost c£9 from BMW (with 10% BMWCC discount). Had a hole on the underside which was drawing in air, she failed her MOT on emissions.the big rubber air hose may split if it's perished and cracked already
I really do need to learn how to use the "quote" function properly, how do you get folks monicker to head the quote...?
Billy, your car sounds lovely mate, how did you come across such a good example?
P.S. If your AFM isn't adjusting correctly it can just be the fin that's 'sticking', cleaning it with carb cleaner can do the trick... though if you are confident about the replacement and have it already then maybe just as well to swap it
'89 325i - was an SE but not anymore, was bronze-beige metallic (yeuch!) but now techno-violet (thankfully)
'89 Toyota Corolla GTi-16 - track, hillclimb & sprint car (yeeha!)
'08 Buell XB12Ss - American engineering at it's 'best'... good fun though
'89 Toyota Corolla GTi-16 - track, hillclimb & sprint car (yeeha!)
'08 Buell XB12Ss - American engineering at it's 'best'... good fun though
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Brianmoooore
- E30 Zone Team Member

- Posts: 49360
- Joined: Mon Jan 10, 2005 11:00 pm
To test an air flow meter, you need to connect a 6V battery across pins 3 and 4 and measure the voltage across pins 2 and 4 with an ANALOGUE volt meter while you operate the flap by hand.
The meter reading should increase smoothly with no jumps
The meter reading should increase smoothly with no jumps
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DaveD
- E30Zone Wiki Specialist
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- Joined: Tue Jan 11, 2005 11:00 pm
- Location: Sheffield
just press the "quote" sign and it brings up a reply box with it in
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garyp_E30_325i
- E30 Zone Regular

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Aaaah, like this!DaveD wrote:just press the "quote" sign and it brings up a reply box with it in
I had been using the "quote button" from the "post a reply" window, as opposed to the "quote box" on the top RHS of the thread...
Thanks for the advice, this has been annoying me for a while now!
'89 325i - was an SE but not anymore, was bronze-beige metallic (yeuch!) but now techno-violet (thankfully)
'89 Toyota Corolla GTi-16 - track, hillclimb & sprint car (yeeha!)
'08 Buell XB12Ss - American engineering at it's 'best'... good fun though
'89 Toyota Corolla GTi-16 - track, hillclimb & sprint car (yeeha!)
'08 Buell XB12Ss - American engineering at it's 'best'... good fun though
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billy
- E30 Zone Newbie

- Posts: 4
- Joined: Fri Mar 25, 2005 11:00 pm
Well, just changed the air flow meter it took 10 mins and my Granny could hiv done it, AND the car ran perfect ...........untill I stopped it again 10 miles away! AND back to surging. Thats the local garage off my xmas list .....anyone want to buy a third hand air flow meter???
DaveD you mentioned cleaning the ICV ???? can i call my granny to do this too mate
DaveD you mentioned cleaning the ICV ???? can i call my granny to do this too mate
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DaveD
- E30Zone Wiki Specialist
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- Joined: Tue Jan 11, 2005 11:00 pm
- Location: Sheffield
