Afm Questions And Tps Questions

[floodys 4 1 Cars]

Just a few questions for you, on the AFM the "cog" inside i think tightens the spring and also richens/weakens the mixture? correct? i only say because with my mi if i wind it up a few click the car runs a lot better!! i think its richen it up, i tried to re-track the afm tonight and i havent run it properly yet. also, on the mi afm it has a different kind of mixture screw i.e not mechanical, with my gas tester connected i cant seem to adjust the settings by winding in and out the screw ( not sure if the switch could be duff (blue thing!!) anyway of testing?)

 

another thing, if i were to have a new/second hand AFM how would i set up the "cog wheel" as per the factory setting?

Just one last thing for now, the throttle pos switch, when the throttle is closed and then slighty open throttle it should click right? if it dont click would the car not idle right or is that down to the idle control valve??

 

sorry about the long winded questions but i'm just trying to get the set up of a mi clear in me heed!!!

[Shepp354 0]

My experience of AFMs is for the 8v but I think the principles will be the same.

 

Moving the "cog" to tighten the spring (clockwise) will actually weaken the mixture. Taking a given amount of airflow through the AFM the flap will move less with a tighter spring than a looser spring resulting in it not moving the contact as far across the resistor board.

 

With an 8v I've found that the cog needed moving up to 4 teeth before a really noticable result was felt on the road. This is just by feel and not with any solid measurement. Even 4 teeth makes no noticable difference on the plug colour with my car.

 

I have a few AFM which I've had the top off and the position of the cog has been different on them all so I don't think there is a set factory position for them. I guess they are set on a test bench and differ according to natural differences in the spring on assembly. They are all 2nd hand though so anyone could have had a go before I got there.

 

The TPS should click as you open the throttle but it doesn't make much difference to the way my car idles. I think it is mainly to tell the injection system that you have closed throttle (over run) at higher revs and to cut the fuel for economy. With it disconnected mine pops and bangs through the exhaust when you lift off at high revs.

 

Not an MI but hope this helps