Quote:
Originally Posted by 801coppertop
Andrew - (I have spent much time on your site, thanks so much for all the great information!) Ive been driving around with an oscilloscope setup in this fashion for a bit. Ill give it another go once I re "baseline" the CO and Idle and let yall know what I find.
I also have datalog showing the issue if thats at all helpful.
Top is running well between 45-55% Dwell - Bottom is after heat soak startup - running not so well.
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I had to check what "heat soaked" means, and ... now to me it seems your residual pressure could be below specs. As regarding to your latest info: if engine is warm duty cycle swings around 45 and 55 % with a resulting proper AFR. But after heat soak startup it gets messed up.
So ...
1. Do what mysocal911/Dave said, means if with disconnected sensor and therefore ECU in closesd loop mode and by this with fixed duty cycle, check if problem still exists.
If yes, then ... its cause the ECU, even in closed loop mode, enrichens with 65% duty cycle directly on start up, which corresponds to your second graph where at the first 15 secs the AFR results too low.
2. If problem still remains, check all Pressures
https://nineelevenheaven.wordpress.com/adjusting-the-warm-up-regulator/
especially
the residual pressure if within spec.
3. If problem still remains, proceed with the suggestion/info Thomas provided. But I don't think on the first view that it's a false air issue cause, regarding to your second graph, after 15 secs on start up the AFR rises to proper values
And last but not least ..... with the second graph you posted it would
be essential to know how the existing duty cycle values are corresponding to "that" graph. This would give a precise diagnosis of how the ECU works, means if it trys to compensate false air, or too low residual pressure or whatever ...