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Tuning AFM
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TOPIC: Tuning AFM

Tuning AFM 8 years, 11 months ago #11260

One thing I haven't seen explored much online is how and why to tune the AFM. I see Joe posted up a while back on the NASA Spec boards that removing the cat as we do can mess with A/F ratios, and that there is some benefit to fixing this with an AFM tune. I'm interested in what people have found with this. What A/F ratio are we shooting for? Do you guys adjust the wiper/track, the spring tension, or the air bypass screw on the AFM? How much does a click one way or the other change things? After we've found some lean issues in local cars, I've just put an AEM A/F ratio gauge, and will log this with the Traqmate. I'm happy to share what I find, when I do start checking things out.

Thougts & experiences?
Eric Kuhns

National Director Emeritus

2007, & 2008 National Champion
2011, 2012 2nd
Last Edit: 8 years, 11 months ago by Sterling Doc.

Re: Tuning AFM 8 years, 11 months ago #11278

I'm disapointed that no one has responded to this post. I am also looking at putting an A/F ratio gauge in the car and wiring it in to my Traqmate, so I am really interested in any information on this topic.
Steve Marlow
944 Spec #47x
NASA Certified Instructor
NASA AZ Licensing Director
2012 AZ Region 944 Spec Champion

Re: Tuning AFM 8 years, 11 months ago #11283

  • cbuzzetti
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Sorry guys did not see this till now.

I to am surprised that more did not chime in. Might be that like me we do not know that much about tuning the AFM.

My experience with tuning an AFM is from Spec Miata. At that time therer did not seem to be anything to be had except the possibility of screwing it up.

The only time I have tuned my car was on the dyno and I used the DME adjustments. Making sure all pertinent things were good before going to the dyno. Fresh plugs, balanced injectors, wires, fuel etc.

At Miller in 09 I ended up making the mixture richer because it made 1 more HP. It was the opposite of what you would think should be the right choice.

I am looking for a recent dyno sheet for my 924s car. Cant seem to find one here so will see if I can get the shop to send it to me.

Unless there is a clear problem showing up on the plugs or in the tail pipe my guess is that you are not far off. The indicators will be obvious. Black sooty tail pipe or plugs, or a way too clean plug possibly even white.
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Re: Tuning AFM 8 years, 11 months ago #11285

  • Big Dog
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I keep looking at this one, too, because I do not have anything to contribute due to knowing nothing about the subject. Doc, I hope someone gets in here to enlighten all of us.

Big Dog
Jim Foxx

Re: Tuning AFM 8 years, 11 months ago #11288

  • JerryW
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You might find some light reading here

www.the944.com/afm.htm
Jerry Whitteridge
Norcal #552

Re: Tuning AFM 8 years, 11 months ago #11289

Thanks Jerry.
TYLER PALMER 2010 NATIONAL CHAMPIONSHIP RUNNER UP 2011 NATIONAL 944 SPEC CHAMPION 2011 SO CAL REGIONAL CHAMPION 2012 NATIONAL 944 SPEC CHAMPION 2012 SO CAL REGIONAL CHAMPION 2013 NATIONAL 944 SPEC CHAMPION
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