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pugman

Dodgy Afm?

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pugman

I've just replaced the AFM on my 1.6 with one from a scrap car because the one I had on was giving me trouble. The "new" one is noticeable better with improved acceleration and hopefully fuel consumption ( its only been on a week) . The only problem is that sometimes when starting when the engine is cold, the engine is hesitant when I rev it and the rev counter is doing some crazy sh1t jumping around all over the place. The rev counter even jumps around when the engine stalls! I've never had this problem with the previous AFM

 

Does anyone know what's causing it? Also the "new" AFM had an electical connector below the socket, but there was no wire going to it on the scrap car. The previous AFM didn't have this. Is this intended to be an extra earth wire?

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Pug_101
I've just replaced the AFM on my 1.6 with one from a scrap car because the one I had on was giving me trouble. The "new" one is noticeable better with improved acceleration and hopefully fuel consumption ( its only been on a week) . The only problem is that sometimes when starting when the engine is cold, the engine is hesitant when I rev it and the rev counter is doing some crazy sh1t jumping around all over the place. The rev counter even jumps around when the engine stalls! I've never had this problem with the previous AFM

 

Does anyone know what's causing it? Also the "new" AFM had an electical connector below the socket, but there was no wire going to it on the scrap car. The previous AFM didn't have this. Is this intended to be an extra earth wire?

 

Have you replaced the AFM with one that has the same part number?

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pugman
Have you replaced the AFM with one that has the same part number?

 

 

Yes, it has the same part number

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ada205

Are you sure it's cus of changing AFM's that it's developed this fault? Have you tried changing back to old one to see if it cures it? Cant really see how AFM would cause these symptoms, many car's like my own use standard ignition with carbs, so no AFM on the car, but rev counter still works ok.

 

Are you sure you havnt disturbed some wires when changing the AFM? Check any in the area you was working. There's a few in the same area that are related to the rev counter. Check leads to coil if type that lives in back passenger-side corner of engine bay, near the expanstion tank, ignition amp and lead from dizzy that's very close to where you would have being working if the AFM is in it's original position.

Edited by ada205

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Rob_the_Sparky

The rev counter opertaion does not depend on the AFM so it is not likely (bar bizarre electrical fault) for that to be the problem. Almost certainly a pre-existing problem or something that has been disturbed when changing the AFM.

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pugman
The rev counter opertaion does not depend on the AFM so it is not likely (bar bizarre electrical fault) for that to be the problem. Almost certainly a pre-existing problem or something that has been disturbed when changing the AFM.

 

I agree the AFM has no effect on rev counter - definately disturbed something but what would cause the rev counter to jump around after the engine has stalled. Would it be loose connection or electrical interference?

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Rob_the_Sparky

AFAIK Rev counter moves in relation to pulses, not a voltage level, so if it were a loose connection then it would have to be flapping around to move the needle.

 

Interference sounds more likely but what from given that the main source of it are the sparks, which have just been turned off!

 

Really I'm not sure I'm afraid.

 

Rob

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pugman

I think i need to have a good look around at all the connections then. I haven't had any trouble for the last couple of days.

 

The engine is running sweet now. Fuel consumption is much better - from 22MPG to 29MPG :)

 

Does anyone know what this connection is on the AFM. Its an insulated teminal - is this standard or something somebody has added?

 

May06.jpg

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hexhamstu

it looks added to me.

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steve@cornwall
it looks added to me.

 

Not a terminal- it's a bendy tie back for the afm wiring!

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Rob_the_Sparky

and it is a standard Pug item

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