AFM Symptoms when f@*k*d up !

[haffeel]

Yah thats it, Please list down the complete list of symptoms when an AFM in an E30 325i is no longer working properly.

Much apprecited.

TQ TQ TQ
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[haffeel]

Guys, can any one confirm this. I was speaking to a guy, and I was told, there is nothing much to gain from tweeking the AFM. such as adjusting the CO2 etc.,

reason

AFM CO2 adjustment is valid only for when the car is idle, during normal run AFM has no function. How true is this?

My biggest pain right now, in the morning when it is cold or when it is raining which means again the environment is cold, my car hesitates during driving and some time I hear loud bang like "DANG" coming from the engine compartment. this really frightens me.

I am going to change the BLUE sensor next week, since this funny situation is temperature related.

Has any one faced this kind of problem. How did you solve it. Did you fiddle the AFM or simply change the BLUE sensor ?

thanks,

[haffeel]

Guys check this out

When the O2 sensor begins to wear out, you may notice the car runs a bit sluggish, fuel economy may be down, and in sometimes, it may cause an annoying intermittent surging idle problem, (as was the case on my car). Once I replaced the O2 sensor, I noticed a increase in gas mileage as well as a mid-range increase in power and drivability.

http://www.pelicanparts.com/BMW/techart ... Sensor.htm

Is that article relavant to my problem?

[Brianmoooore]

Guys check this out

When the O2 sensor begins to wear out, you may notice the car runs a bit sluggish, fuel economy may be down, and in sometimes, it may cause an annoying intermittent surging idle problem, (as was the case on my car). Once I replaced the O2 sensor, I noticed a increase in gas mileage as well as a mid-range increase in power and drivability.

http://www.pelicanparts.com/BMW/techart ... Sensor.htm

Is that article relavant to my problem?

Unless you're not in the UK, or have a late E30 with all the emissions stuff, then no relevance at all, since you don't have an O2 sensor.

[Brianmoooore]

Guys, can any one confirm this. I was speaking to a guy, and I was told, there is nothing much to gain from tweeking the AFM. such as adjusting the CO2 etc.,

reason

AFM CO2 adjustment is valid only for when the car is idle, during normal run AFM has no function. How true is this

AFM does nothing much at idle, since the flap is just about on it's stop, and the TPS switches the ECU to th idle settings. The air bypass screw on the AFM is used to adjust CO level at idle, which is import6ant to getting your car through an MOT test.
An E30 will idle OK with the AFM disconnected from the throttle body.
Off idle, the airflow meter flap moves and provides a signal to the ECU. With this big hole bypassing the bleed passage, the CO adjustment screw will now have little effect.

For any temperature related problem on an E30, the blue temp sensor should be the forst thing you change.

[haffeel]

Hi Brianmoore,

My E30 is a late model and YES it has an O2 sensor. Yesterday I disconnected the plug of O2 sensor and saw the pins are all coated with salt like layer, today I will clean it throughly.

I will also change the BLUE SENSOR today as I understand the BLUE sensor sends information direct to the ECU.

So according to your reply, looks like if the AFM is faulty then sure it must be changed. Is that right ?

thank you for the reply,

[Brianmoooore]

I haven't said anything to suggest the AFM is faulty, and I can't see why you seem to think it is.
Sort the blue sensor and the O2 connections and see what it's like then.
There's also a round plug and socket fixed to the bracket under the inlet manifold that carries the signals to and from the two temperature sensors and the injectors. Might be worth checking this one is clean and bright as well.
A bit of silicon grease on the pins of all these plugs and sockets will help keep them bright and shiney, once you've cleaned them.

[haffeel]

BrianMoore,

In couple of hours I am going to change the BLUE sensor and clean the O2 sensor connection. I too strongly beleive the AFM should be OK.

any way after reading this http://www.unofficialbmw.com/all/motron ... ments.html

I am pretty sure the AFM is alright.


thanks

[haffeel]

Hi BrianMoore,

I changed the BLUE temperature sensor 2 days back now three quarter of the problem of hesitation during moring and rainy time is gone .. no more DANG sound fromt he engine compartment.

This is a real fast solution for a cheap price and I installed it myself

really a good experience. I find after pro long driving when I come to a stop and then driving off the car feel sluggish .. this one obviously the the fuel supply is not very consistant. So I suspect the AFM is faulty.
Now I am going to change the AFM as well

thanks BrianMoore,

cheers

[Andy_magic]

There is an air temp sensor inside the AFM. I have found that cleaning this sensor gave improved running in colder/damper weather.

I used carb cleaner spray to clean my AFM out, I think the sensor gets coated with a film of dirt etc after 10 plus years of being used, a film of dirt or whatever could cause the sensor to read the temperature higher than it really is.

[haffeel]

Hi andy, Yes today I saw that some thing potruding like a sensor kind of thing. It did look dark browinsh glowing thing. Didnt know that was gunk .. will clean it up with carb cleaner this week end and try again.

thanks for the tip

cheers/haffeel

[haffeel]

Hi all,

Today I changed a new but used AFM with a serial number ending 082, for 325i.

Now all the hesitation sickness during cold, damp time during rainy time problem all got solved.

the car is working very smooth and I can see the increase in power. I am so scared of this AFM thing, I dont want even to make any ajustments. and it is working real fine.

Moral of the story. If you no vacuum leaks, for all kinds of hesitation problem, change the BLUE sensor and then take a good look at the AFM.

This problem was hauting me for nearly 6 months, only now it is solved.

cheers

[Andy_magic]

Glad thats sorted.

[haffeel]

Mmmhh the story does not end here

I had to adjust the AFM at idle at 1.4 CO volume value, only after that I seen proper power gain in the installed AFM.

Now the subject is closed.