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
Retracking AFM
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.
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.
Re: Retracking AFM
What Kitch has told you is not strictly true.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
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
Please call me Luke
1989 BX 16valve White 70k almost up to scratch
1989 BX 16valve White 70k almost up to scratch
Re: Retracking AFM
Oh b*****ks. Well whatever I had done wasn't retracking then. But it workedToddman wrote:What Kitch has told you is not strictly true.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
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