Engine

Rough Idle / Incorrect Fuel Mixture

#1
I spent a couple hours this weekend under the hood inspecting and cleaning as many electrical connections as I could get my hands on. What prompted this activity (beyond the obvious love for getting my hands dirty) was a slightly rough idle, a noticeable reduction in gas mileage, and an annoying exhaust/engine snarl above 3k rpm. Primary suspect was the air-flow sensor: I pulled it out and did a direct resistance reading (in spec) then gave some attention to the connector (both ends had a LOT of green corrosion/buildup on a couple of pins.) Got the connections clean and shiny and replaced the sensor. The same was done for the temp sensors and as many other connections as I had the patience to try. After buttoning everything back up, putting away the tools, and getting a goodly portion of the dirt off of my hands, I hopped in the seat for a spin. Then I got back out (decided it might be a nice idea to reset the system by disconnecting the battery lead.) When I finally started the beast up, it snapped to life (no big surprise, it always does :) ) and the idle wasn't just smooth like usual, but dead calm!

#2
Just because the air flow sensor passes the resistance measurement tests given in the service manual does not mean that unit is in proper operating condition. It may be necessary to swap a known good unit into your car to find out for sure.