In the Forums, I have not seen any Intelligent discussions of how the Idle Circuit Works..
This Talks about Tuning for running.. [ http://www.ztechz.net/id10.html ] And the Forum that it links to I can only find Running Tuning Chat..
And this Post Talks about Low Speed Driveability.. but Nothing of how the Idle Circuit Works..
[ http://www.twinturbo.net/nissan/300zx/forums/general/view/2514673/Timing-Map-Modifications-to-Enhance-Low-Speed-Drivability.html ] Talk to any Smog Guy, and they will tell you for an Engine to Pass Smog, the Combustion Process before the Cat needs to take place NEAR Stoch, for the Cat to clean it up. THEN the Cat needs to be Fed with Fuel and Air to complete the 'Cleaning' Process.. FACT:.. I have watched the O2 Sensors on my 95NA, 'Dithering' above and below Stoch while Idling.. I used the Volt Meter, and hooked to the Narrow Band Sig while the Car was Idling in the Driveway. FACT:.. I have watched the O2 Sensors 'Dithering' Above and below Stoch on my 92NA while it was sitting in the Driveway.. One O2 Sensor was not Cycling when I got the Car, and I replaced the O2 Sensor, and it Started 'Dithering' at Idle.. Yes the Car had a Cell for O2 Sensor Malfunction. Fact: The 92NA Still has the AIV's but was running a JWT FED 16Bit ECU for the '95NA. It runs SOOO Much Nicer with that ECU.. The 90-92's have the AIV's to supply Excess Air to the Main Cat for RPM's below 2K. If you remove the AIV's and do not use a 'Non AIV ECU' they will not pass Smog for Idle, Usually Excess Hydrocarbons and CO.. If you Install a NON AIV ECU they will Pass, provided the Car is Healthy.. Mine Did. As Stated, i have watched my 92NA do a 'Fuel Correction Closed Loop Mixture Control' while Idling. I have not Reinstalled the 92NA 8Bit ECU that has AIV Control, to see if it will also do 'Closed Loop Control' of Idle Mixture, or whether the Mixture will stay Fixed.. The On Line Nissan Book, Talks about AIV's and Proclaims the Idle to be an 'Open Loop Control'.. My 95 Book does not mention IAV's ( They were not installed after '92 ) and Still calls Idle an 'Open Loop Control'.. SPECULATION.. is it Posable the AIV ROM is programmed to NOT used Closed Loop Feed Back Control of Idle Mixture, and the Design is to Inject Air by Way of the AIV's. This would explain why the On Line Book is calling the AIV's Idling an 'Open Loop' Control. The '95 book was not changed to reflect the 'O2 Dithering' that the '95 ROM Does for Idle Mixture Control?.. Cj
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