D-jet idle and lean issues. Options

[Literati914]

1.7 w/ original D-jet.

I have the idle screw on the TB cranked all the way down/closed (which doesn't seem right tbh) and the car's idleing around 900rpm - which is within the recommended 850+/- , and the idle does not really "surge" too much but is not necessarily rock steady either. I'm also getting a steady 16.5 A/F on my gauge during idle and warm driving. So too lean. BTW, the CHT gauge has never gotten over 300 so it's not trying to over heat.

I'll be spraying the vacuum connections to see if I can find leaks - but other than that, what would be the most obvious culprit(s)?

My theory is that the idle screw needing to be closed (for a reasonable idle) is just combating say, a bad AAR or something. Sound logical? What tests can I do to the AAR or other items to look at first?

[emerygt350]

Mixture is unaffected by leaks. Idle rpm is. I agree that you are probably looking at a leak in the TB or plenum. Can-o-carb cleaner is your friend. Spray it around the TB, runners, etc, if the idle drops you found it. My car leaks around the idle screw but only there, so I just leave it all the way in and call it even.

As far as your idle mixture.. Do you have the idle mixture pot on top of the ECU, I don't think you do with a 72. And to reiterate above, did this just start all of a sudden? And what is the mixture like while driving? Does it never go over 300? Seems a little cool, like your engine is not performing as it should.