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Tuning AFM
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Re: Tuning AFM 9 years, 10 months ago #15402

  • phlip
  • Comp School
  • Posts: 35
Be dubious all you want, buy what ever you want. This tune was done after complete engine overhaul on a used spec car, the engine was junk, I purchased a used M44/09, preformed overhaul, and broke it in on the dyno.
I got no reason to lie, maybe the AFM had been adjusted for the whipped engine I removed from the car.
I'm not allowed by rules to adjust anything but the AFM. So Ignition timing was unchanged.
FR Wilks post sounded to me like he making the claim that adjusting the AFM was not a good idea. His first post by the way. After reading some info in links in his sig I know this is exactly what he was saying.
I'm saying dont be afraid of adjusting the AFM.
These engine managemant systems are very low tech compared to new cars.
As I said I've done it to many cars for many reasons, tuning, smoothing idle,
emissions, its not hard.

RangerGress wrote:
phlip wrote:
Thats funny. Reading one of the links in your sig it says never adjust the spring tension of the AFM. Adjusting the spring tension of the AFM is how I went from 128 to 139 horsepower in less then an hour of dyno time. It's also how I've got dozens of pre-OBD2 cars equiped with AFM's to pass state emission tests.

I'm dubious. That's a helova lot of hp increase. Rigorously testing engine management changes via dyno runs is not infantry simple. It's hard for me to buy that Porsche left 11hp on the table that could have been recovered with a few spring clicks.

At a minimum, a careful analysis would have to be done re. what was changing (F/A, spark advance, etc.) in good runs vs. bad runs, and it would have to be repeated multiple times to confirm causality. Once can't just twiddle something, do another run and exclaim "wow, 11hp. Time to go home".
Phil --------
944 SPEC #030
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