1993 Nissan Sunny 1.4, wants help to adjust engine's idle speed . Pls. Help! Thanks Ken?

Question

1993 Nissan Sunny 1.4, Manual, Patrol. Serviced recently
wants help to adjust the Engine's idle speed.
As it Failed Exhaust Emissions Test on only Naturel Idle Test : Co result is 1.36% vol instead of below 0.50% vol! limit, other test ok!

Pls help to adjust the speed of Sunny's engine or any tips or may be highly appreciated.

Thanks again
Ken

Answer 1

OK, I am fairly sure that this vehicle is fuel ijected. Fuel injected engines are not adjusted like carburated engines.



In a fuel injected engine the air/fuel ratio (as well as idling speeds) are adjusted by the ECM (electronic control module) often times referred to as the "brain". The brain uses several sensors to measure factors impacting the engines performance. Upstream " before the fuel injector there are mass air flow sensors as well as intake air temperature sensors. Downstream "after combustion" the oxygen sensors feed data to the ECM. The ECM uses all of this data to continually adjust the air/fuel mixture to keep it at its peak ratio (between 11to1 and 16to1 ration of air to fuel for most engines). The problem is that if any of the various sensors go bad the ECM will stop making fine tuning adjustments and go into a "loop" mode which is a preprogrammed calibration that supplies a constant air fuel mixture. What you end up with is erratic performance, poor fuel economy, high or surging idle speeds. You should have a "checdk engine" light illuminated alerting you of the senor failure though.



Another thing to look at would be your AC idle control solenoid "called other things depending on your vehicle" but this solenoid senses when you have you Air conditioning on and supposedly slightly ramos up idle speed to off set the increase drag put on your engine by the AC compressor. This solenoid is notorious for cause high idle issues.



Of couse all of this is fodder if your vehicle has a carburator on it. My suggestion to everyone is to go buy a book on your vehicle (I have one for every vehicle I own including my boats and motorcycle) these are written in laymans terms and will walk you step by step through most maintenance/repair issues. I suggest Hayes Manuals since they ae sufficient and the cheappest you can buy (around $15 US)

Answer 2

Try setting your carg idle speed screw situated along side of carb

Answer 3

well i had a problem like that too. i changed my catalytic converter and it passes smog.... something u mite wanna look up