BX16V.com Forum

OK, novice question alert. What does "retracking" the AFM actually mean? Cleaning, replacing the track...? The top of mine has been taken off and then glued back down again, I want to know what I'm doing before I butcher it further.

Reason I ask is, my 16v has been failing to start from hot, intermittently, for a while now (it will start but needs some throttle, and won't idle, just stalls... after a while it sorts itself out). The other night it stalled after some lights going uphill in the outside lane of a dual carriageway (embarrassing). Managed to get to the side of the road... cambelt worries at this point so didn't try to bump it! Checked everything, all seemed ok, and it would turn over on the starter but not catch. I reasoned it must be fuelling. Fiddled all the available connectors - AFM, idle valve, injectors, etc. Car starts, and seems quicker than before

Clearly all the connections need a thorough clean! But I thought while I was at it I would make sure the AFM is operating OK. It's drinking petrol at the moment and I suspect it is running rich...

Since I'm planning on giving it new plugs, leads, filters and exhaust within the next two weeks, I think overhauling the AFM etc is in order too... at the moment it drives like a normal car

The AFM is basically a resistor and as the engine draws air in it opens a flap. As this flap opens it moves a needle which alters the flow of electrical current going back to the ECU so that in turn varies the fuel being injected to compensate.
Retracking is to do with the position of the needle in relation to the flap. If it was wrong, the flap could be fully closed but the needle might be reading too high giving a false single and vice versa. I think they can go out of track over time. By retracking, you get the needle and flap perfectly aligned so you're getting the optimum fuel/air mix.

I understand the theory but physically what do you do? Just clean the track? Or install a new one? Is there an adjuster for the flap position relative to the compression of the spring?

We hooked it up to a Co2 machine, pulled the cover off the AFM and moved the round cog a bit until it seemed to be running happier and at the right Co2 level. The Co2 screw in the back allows fine tuning of it once the cogs in a better place.

djoptix wrote:OK, novice question alert. What does "retracking" the AFM actually mean? Cleaning, replacing the track...? The top of mine has been taken off and then glued back down again, I want to know what I'm doing before I butcher it further.

Reason I ask is, my 16v has been failing to start from hot, intermittently, for a while now (it will start but needs some throttle, and won't idle, just stalls... after a while it sorts itself out). The other night it stalled after some lights going uphill in the outside lane of a dual carriageway (embarrassing). Managed to get to the side of the road... cambelt worries at this point so didn't try to bump it! Checked everything, all seemed ok, and it would turn over on the starter but not catch. I reasoned it must be fuelling. Fiddled all the available connectors - AFM, idle valve, injectors, etc. Car starts, and seems quicker than before

Clearly all the connections need a thorough clean! But I thought while I was at it I would make sure the AFM is operating OK. It's drinking petrol at the moment and I suspect it is running rich...

Since I'm planning on giving it new plugs, leads, filters and exhaust within the next two weeks, I think overhauling the AFM etc is in order too... at the moment it drives like a normal car

What Kitch has told you is not strictly true.
Retracking is not resetting the output from the AFM it is "retracking" in the purist sense.

The AFM has a contact attached to the vane and this runs along a carbon track - after time the track where the contact moves becomes worn so a new track is needed to give a good contact.

So you move the contact in/out a little so that it runs along a new path i.e. a new or retarck.

The cog that Kitch mentions does alter the mixture but that is not "retracking".

Hope that clarifies it

Cheers
Luke

I had a go at this recently, as my power was down betwwen 3-4k, ideal moterway cruising speeds. i just bent my swing arm up and kinked it a bit. didnt seem to do too much, however a mates car does seem to run a lot better with my afm on it.

Toddman wrote:

djoptix wrote:OK, novice question alert. What does "retracking" the AFM actually mean? Cleaning, replacing the track...? The top of mine has been taken off and then glued back down again, I want to know what I'm doing before I butcher it further.

Reason I ask is, my 16v has been failing to start from hot, intermittently, for a while now (it will start but needs some throttle, and won't idle, just stalls... after a while it sorts itself out). The other night it stalled after some lights going uphill in the outside lane of a dual carriageway (embarrassing). Managed to get to the side of the road... cambelt worries at this point so didn't try to bump it! Checked everything, all seemed ok, and it would turn over on the starter but not catch. I reasoned it must be fuelling. Fiddled all the available connectors - AFM, idle valve, injectors, etc. Car starts, and seems quicker than before

Clearly all the connections need a thorough clean! But I thought while I was at it I would make sure the AFM is operating OK. It's drinking petrol at the moment and I suspect it is running rich...

Since I'm planning on giving it new plugs, leads, filters and exhaust within the next two weeks, I think overhauling the AFM etc is in order too... at the moment it drives like a normal car

What Kitch has told you is not strictly true.
Retracking is not resetting the output from the AFM it is "retracking" in the purist sense.

The AFM has a contact attached to the vane and this runs along a carbon track - after time the track where the contact moves becomes worn so a new track is needed to give a good contact.

So you move the contact in/out a little so that it runs along a new path i.e. a new or retarck.

The cog that Kitch mentions does alter the mixture but that is not "retracking".

Hope that clarifies it

Cheers
Luke

Oh b*****ks. Well whatever I had done wasn't retracking then. But it worked