precat AFM setting

[Barreti]

At the Griff Grumble FFG discovered my AFM setting was set at the value for a cat equipped car, not a precat.
Rather than tweak it there and then, I changed the spark plugs yesterday and adjusted the AFM to the correct precat setting and I'll pull a plug in a few weeks to make sure it isn't running lean.
Tickover is absolutely lovely though and if anything it feels to be running better, though I can't discount that just being in my head because I know it has new shiny bits in.

So precat owners, something worth checking if your car is running rich.

Pull the rubber boot off the plug on the AFM and put a multimeter across the wires on the far left and far right.
It should read 1.4v for a precat.
I fitted a new AFM last year and it turns out it still had the default setting for a cat equipped car.
1.83v is the Serp setting. 1.4v is the correct precat setting.
If you look at the back of the AFM you will see a circular lump in the casing. stick a flat bladed screwdriver in there and turn it to adjust. Go steady, it adjusts quickly.

[FlipFlopGriff]

Glad its running better Ian.
Be interesting to see what the fuelling is like now. I've just bought all the equipment to get me going on Rovergauge but not used it yet.
Modern computers don't have a CD drive so need to get an external one.
FFG

[blitzracing]

you can download the CD here straight onto your PC.


https://www.dropbox.com/sh/i0acxr8nwr10ow6/AAAIPux...

Hope this helps.

[FlipFlopGriff]

blitzracing said:

you can download the CD here straight onto your PC.


https://www.dropbox.com/sh/i0acxr8nwr10ow6/AAAIPux...

Hope this helps.

Thanks Mark.
FFG

[Barreti]

I knew I'd read somewhere about this, again, thanks to FFG
It's all Here

[stevesprint]

Barreti
Well done for bringing the CO trim adjustment screw to every precat owners attention as its one of the most common causes of fuelling complaints like shunting, hesitation, fumes and MOT emission test, plus its fairly simple to correct provided you have a multi-meter or RoverGauge. Please note not all cars are the same but 1.4 volts is a good starting point and if still shunting then try turning clockwise in half turns. Also cat owners please note the CO trim screw is ignored when running a cat map.