Hi all

What does this screw adjust...


The reason I ask is because when I took the car to a pals garage he stuck something up the exhaust to see if the car was running rich or not ( I think it was the tool that measures emissions for the mot), and he was concerned that it was running very lean. He said that adjusting this screw would alter the air/fuel ratio. This is an afm I bought off a fellow member, and it had a solid alloy blank that I drilled through today to get access to the adjuster screw. My old afm did not have the alloy blank.

Anyway, I know that my best bet is to get on a rolling road and get it done properly, but you know what friends are like, they think you should jump at the chance of free attention to the car and might get relatively upset if you tell them to begger off. He is putting my car through a pre-mot tomorrow; should I tell him to leave the screw alone (I only drilled the alloy blank out for him really ) or let him play and try to get the car running alittle richer?

Ho does know what he is doing in general, but these gt4's aren't the norm are they

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Karl
white 205 jdm 1996

Karl - have seen AFMs with and without a blanking cap for the screw. It is a little unusual from memory to have an aluminium "bung" covering it over though.

From memory the screw adjust the amount of air flowing through a bypass passage around the AFM flap. This by it's very nature will alter the afr. This is designed to only alter the idle afr.

Restricting the bypass i.e. adjusting the screw will cause more air to flow through the afm and hence push the flap open, and so increase fuelling.

I would've though you would be aiming for an afr of 14.7:1 at idle. Am a little surprised that this would need to be adjusted as the lambda sensor is helping to adjust the afr closer to 14.7:1?

Sure it's not the lambda sensor or a leaky pipe somewhere? Think that the typical lambda sensor failure causes the engine to run a tad richer than it should normally...

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Kris
95 ST205 - slept for 10 years, now waking up...
Avensis
http://www.gtfours.co.uk
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Turbocharging - the replacement for displacement