BMW Air Flow Meter Problems - HELP

energy69

I've just spent €800 getting a service plus extras done on my '97 523i. Only had a new tube connected to the Air Flow meter replaced to find last night the car started acting really strange. Kept losing acceleration and speed dropped down. The more I drove it the worse it got to the point it was going 5 miles per hour and cutting out every couple hundred meters.

Asked in Otto and they said I needed a specific one they had for €300 and to call out and get it. It was the wrong one and the one I needed is a Siemens 5wk9 600 model. I heard a quote of €500 approx so far and it seems crazy. Spent a good few hours Sat looking around scrap yards for a second hand one to no avail. There appear to be ones available on Ebay for €100 although this seems a bit sus. I really need my car at the mo. Has anyone got any suggestions as how I can get this sorted without having to pay this insane money for something that looks like it should cost €50? All help and suggestions very welcome.

Sam

mike65

So the car was okay until the tubing was replaced?

Mike.

Mr.Diagnostic

I would be kinda with Mike65 on this. Are you sure you need a new MAF?

Seth Brundle

Firstly why was the tube replaced?
Have you checked for vacuum leaks? Is there any noises from that area?
Go to www.realoem.com/bmw/select.do, enter in the last 7 digits of your VIN and then search for the correct part number for your car. If you do get it from ebay then make sure the part number is the same.
I would suggest asking the same Q on www.bavarian-board.co.uk

mike65

Better lock this one then! *arched eyebrows (Roger Moore style)*

Mike.

energy69

The car started acting strange over a month ago. Revs going up while sitting at lights and randomly cutting out every now and again. I got the car looked at around 10 days ago and my mechanic noticed that the large corner piping directly connected to the MAF had a large crack in it. He ordered the piece and it was fitted on Friday. 3 or 4 hours later the engine reving happened again. That night while driving home the car stated losing power and felt like the car couldn't change gear. Stayed in a low gear and held a speed of around 30mph.

Next morning I drove it around the block and it seemed to get worse. Stopped in a garage and asked a mechanic if he knew what it was from driving it and he said he'd put his wages that it was the MAF. Drove to Tallaght and it got worse. By the time I was coming home the car was doing 5 miles an hour max and cutting out every couple a hundred meters. Car was barely able to hold revs above 1500rpm.

Cheers for all your help. Sorry about not getting back sooner.

Mr.Diagnostic

Hi,

I would suggest you get it looked at again. The pipe you mention would cause a running concern if cracked. No improvement with it replaced is odd. Maybe something was disturbed while it was being fitted. The idle valve and throttle position sensor are both in the same area.
I think MAF's are a bit too dear to replace based on the opinion of someone who didnt test it, unless he did actually test it.

Seth Brundle

I would bring the car to someone who will do a diagnosis on it. As you are in Dublin, try AC cars (www.accarsales.com).

mike65

Better lock this one then! *arched eyebrows (Roger Moore style)*

Now looks completely 'random'! It meant something at the time...honest.

Mike.

macnab

I paid €80 for the MAF for my merc 18 months ago and no probs since so dont judge quality by cost. You might have an air leak in the pipework leading to the MAF. The crank position sensor gives problems on those engines too.

OKenora

Or...(my bet)

The original cracked pipe going to the MAF was allowing in un-filtered air which has crudded up the MAF. Now that the cracked pipe has eventually been seen and replaced it no longer is the problem, but was the cause of the new problem generated by it being un-fixed for a while.

or scenario 2 (less likely)

The MAF has been duff for a bit but the cracked pipe was after the MAF and was totally messing the system, but it ran anyway. Now that the pipe is replaced the MAF needs to be working right but isn't.

TBH the symptoms do sound like a duff MAF. If it won't idle or idles badly with the MAF connected, unplug it and see if it idles better. If it does it's near certainly your MAF at fault.

Whether you need a new one or would get away with cleaning the old one I don't know but if it's been sucking un-filtered air for a bit I would say it's a new one needed. i thought BMW used Bosch MAF's same as Alfas do ? I know you can sometimes get away with cleaning the Alfa ones dunno about a siemens one though.

jo.king

Just to let you know - i bought an Air Flow Mass Meter on eBay last summer ('06) for my Alfa 156 and have had no problems with it at all - bought it for €100 - a fifth of what Advance Pitstop wanted to charge me!

fightin irish

OP i work in the motor trade and had to buy one from Joe Duffy's for €300. Couldn't get one anywhere. I was pretty annoyed alright. My car got so bad it just kept cutting out every 100 yards.

energy69

Thanks for all your suggestions. Yesterday I came home and gave the car a once over just to see what else might it be. I noticed a hissing sound. Not sure how I missed it before. As loud as a fast puncture in a tyre. The car continued to cut out. I went to the internet with my new knowledge and did some research. It appears you can clean your MAF, as suggested by OKenora that that much air being taken unfiltered would have left a load of crud on the MAF contacts. Read up on this online and it appears to be an issue that commonly happens and recommmended that it be cleaned fairly regularly to extend the life and keep up performance. Although this doesn't explain the hissing.

The next thing I came across is that if the air leaks into the air intake manifold it will cause problems with the fuel mix and can leads to similar symptoms as described with my own situation. Then again air leak in doesn't make a loud hissing sound. I dropped into J & S at lunch time and after my 2.5 hour journey home on the bus I gave the MAF a once over. It was filthy with black grime and dirt coming off it. Reconnected it all. Climbed under the car to see if I could isolate the hissing sound. It appear to be coming from around a foot behind the sump and up inside the engine. Excuse my ignorance as to what this area of the car is called.

So, the hissing sound concerns me as I feel in spending €500 on a new MAF may not be the answer especially with this new found hissing sound. I'm working in Loughlinstown and travelling from Kimmage by bus so I'm leaving at 7am and getting back at 6.30 so I have little time to get to any mechanic. All suggestion grateful. Even if I now what the issue is at least I can send the mechanic in the right way.

Cheers

P.S. Yeah the guys in OTTO thought it was a Bosch one also. the 523i of that year takes the Siemens 5WK9 600 at a nice hefty €500. Even J & S siad they haven't sold one before. Strange.

crosstownk

The hissing is, judging by your symptoms, the most likely cause of the problem. The engine is getting excess air and is cutting out because the fuel:air ratio is too low. The MAF sensor is sending back a signal that is within tolerance, but the leak is allowing air into the intake system after the metered air. Everything reads right at sensor level, but in reality things are not so - this is why you probably have no fault light on the dash panel. Find this leak and tape it up with duct tape - if that cures the problem then buy a replacement pipe for the one you taped up.

Do not buy a new air MAF sensor till you cure that hiss.

galwaytt

....the thing is, I can't think of an induction component that far down/low as the OP describes, and, well, ordinarily a 'hiss' is a sound of leaking pressure..........induction/intake systems are more a vacuum system, and leaks tend to be silent..........so I'm not convinced it's connected to the OP problem.

I'm with scenario 2, above, but do check out the hiss and sort it before spending daft money on a MAF. If the hiss is something else, it sounds very, very like your MAF is AWOL. I've had 3 MAF's go on me in 3 cars in 3 years...........all different brands, too, btw..............:mad:

Mr.Diagnostic

Idle air valve is piped into the MAF ducting. If this is not in place it will draw air and it will hiss. Any big Vac leak will hiss. It is not that easy to see either. A Vac leak under the manifold could sound louder from underneath too. Strip the MAF pipe off again and look under it for the idle valve hose.

MercMad

Mr.Diagnostic wrote:

Idle air valve is piped into the MAF ducting. If this is not in place it will draw air and it will hiss. Any big Vac leak will hiss. It is not that easy to see either. A Vac leak under the manifold could sound louder from underneath too. Strip the MAF pipe off again and look under it for the idle valve hose.

............I agree. If you dont cure the hiss then new will still have a problem, new MAF or not ! Check every rubber pipe/hose you can find on the intake side, wiggling them around with the motor running may help you narrow it all down !

richie_rvf

Be very careful if you clean the MAF!!!

They are VERY delicate and brittle!!

You can get a spray can of Isopropyl Alcohol from Maplins, use the entire can, 1/4 at a time, take the MAF out, spray the hell out of it - without touching it - shake off the excess and allow to air dry before repeating.

Keep doing this until the can is empty.

Check all connections when you have the MAF out, slightly twisting each pipe/hose will show up any cracks that otherwise would not be visible.

What mileage is on the car? Those symptoms can sometimes be caused by the Cat, sometimes when the Cat gets old it can collapse inside which blocks the airflow giving too much back pressure.

When you have cleaned the MAF you need to have the car hooked up and diagnosed, you could throw lots of money and time at this problem before you get it sorted.

The lads at AC Car sales are excellent and will help you out.

Best of luck,

Richie.

Lord Nikon

Have you tried disconnecting the MAF sensor, not removing the whole thing, just the cable going up to it. Try this, the car should run a little richer than normal because the engine runs a default setting, with the MAF disconnected.

rebel.ranter

It sounds like you need a mechanic that specialises in BMWs.
If you get it brought to someone with proper diagnostics then you may have a better chance of understanding what's wrong.

The only thing I can think of that is low down that might make a hissing noise is the exhaust manifold, or maybe the inlet manifold itself.
Do you knwo anyone else with a 5 series of the same model? Have a listen to their one to be sure you're not imagining things!

energy69

Cheers again for everyones help, its being brilliant. Okay, took the morning off work and dropped the car into a local mechanic. He ran a diagnostic this arvo and it came back with 8 on the Air Mass Flow, 65 on the Camshaft and 83 on the Crankshaft sensors. They had a MAF and swapped it to see if that changed it and there was no difference. They discovered the following.

1. Two of three of the bolts holding one of the exhaust pipes running from the cat to the engine where gone. This was letting in/out air and was causing the hissing.



2. A very botched job had being done in replacing the CAT (on the mark richie_rvf) with two make shift spurious ones and one had gotten blocked and was causing the main problem.



They said it would cost around €1000 to replace and recommended Fast Fit in Crumlin. They also said you can have a temp job done that will cost arouund €300. I dropped over to FF and was told that they would only replace it with the correct CAT, costing €1150 although I'd get it for €900. They would not offer the quick job and recommended against getting it done as it will only in the long run damage the car.



So, destiny thankfully prevented me from getting the MAF on Saturday and here I now finally know the issue.

Can anyone recommended a more cost effective way of getting this done or is there another option? Did a quick check on Ebay and appears there is none for that model. I have an old 318i, off the road, sitting in my mums driveway for the past few years and I was wondering by some bizarre chance might the CAT fit from that Think I'm being a bit hopeful here. Does it make sense to buy from the UK or anywhere else?

Thanks again everyone

Sam

JohnCleary

Check out www.bmwland.co.uk they'll be able to tell you if theyre interchangable. They'll also advise of a place to get one in the UK at a decent price (If possible). Just make sure you've got someone that'll fit it

richie_rvf

Glad your getting somewhere Sam!

Have a look for High Flow cats, sometimes they can work out a lot cheaper.

I don't know if these guys will ship but it will give you an idea;

http://www.autopartswarehouse.com/apw_cc/cat_basket.php?catalog=catalytic_converter&makeid=3&year=1997&modelid=48

And here's one from the UK;

http://www.cats4less.co.uk/product_details.php?id=71321&system_ref=1&manufacturer=7&model=463&engine=16&product_type=2&searchtype=simple&startpos=0&max=10

Should be easy to find someone to fit it too,

Richie.

mike65

WTF WTF WTF?????? How can www.cats4less.co.uk charge less than a tonne for a new cat section and QF charge over a € grand?

Mike.

bbability

I'm tellin ye it pays to wait and be certain sure of a problem. Glad you got to the bottom of it and good luck with the repairs.