Quote:
Originally Posted by Jonny042
I had no end of trouble with tuning the MFI until I gave up chasing AFR's and concentrated on what the motor likes. My motor doesn't seem to respond to anything over 12:5 either.
It's probably worth a bigger discussion, but these cars seem to like a much richer AFR than ideal. I'm sure there are many factors but it must have to do with the fact that richer than ideal mixtures burn faster.
Unless you can find a pro who knows aircooled cars you might be better DIY'ing the tuning in the long run.
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That makes me feel much better.
Like 20T better.
What AFR are you hitting at WOT?
Quote:
Originally Posted by Jonny042
PS - I should add, not sure where you are having the most trouble, but even at light cruise I'll get a slight stumble at anything in the high 13's. Of course I'm not running vac advance and I'm sure that would help, but just trying to add an FYI point.
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Same.
Quote:
Originally Posted by jpnovak
So... If you are having trouble running leaner than 12.5 you need to add more timing. A rich mixture is slower to burn - up to a point.
General rule of tuning is that to run more lean, you need to add more timing. This rule especially holds at light load and cruise. This is why you see Motronic (3.2 and 964) cars with lots of light load timing. In some cases, higher than 40 BTDC.
Increase the timing at light load and see if that helps you increase the AFR to run more lean.
And yes, Always give the engine what it wants... In some ways you tune by feel/sound.
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I'm in the ballpark of 31-32* at freeway cruising. Once that gets above 12.5-12.7, it gets unhappy.
I think what I'll do is move my AFR targets down .5-.75 and tune to that. Then, I can lean it out and add timing once the darn thing runs like I want.
I may send you my AFR target table and ignition table this weekend for a quick perusal. Let me know if you see anything glaringly wrong?