Re: [Amc-list] TBI fuel injection tuning...

[Tom Jennings <tomj@xxxxxxx>]

This weekend I plan on driving around with the system in open loop to 
tweak the tables into 100% perfection. It's awful close now. Air temp in 
the morning yesterday was 80 (sorry, I don't mean to offend you cold 
weather people) and the BLM (fuel trim) indicated rich (like 1%). At 
night, air temp in the 60's, it was spot on. TBI is one hell of a good 
carburetor!


But I can now see TBI's limitations. Since the oxygen sensors are so 
stupid (they say only lean/rich, basically) the exhaust gas oscillates 
rich/lean/rich/lean/rich/... a tiny bit, all the time, even at steady 
cruise. It's something like 1 - 4 excursions per second, so mixture is 
off-perfect most of the time. This is "transport time", how long it 
takes for a change in fuel at the manifold (your foot, or software 
adjustments) to get detected at the O2 sensor.

So does TPI basically shorten transport time, a lot?


I have "highway mode" disabled now, where it runs extra-lean under 
highway conditions. That's the next project in there I think. I have a 
trip to Tucson coming up in December, so it all better be done then!
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