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Hi All
For the past few years from time to time I have had to adjust the idle mixture on the airflow meter to compensate for a lean idle. All the other sensors had been checked and were within tolerance as outline in the factory service manual, there were no leaks in the intake system, the motor is low milage and has good compression.
I eventually got to the stage were I could not increase the idle mixture ( all the adjustment on the airflow meter does is sent a 0V {lean} to 5V {rich} signal back to the ECCS).
Where I live, 300ZX's are scarcer than Hens teeth so I couldn't get one from a wreck, The one person who does advertise reconditioned one charges two arms and three legs for an exchange one (I think he gets them from the States).
The principle behind these airflow meters is not new (the same techique for ventilators in hospitals). So what I did was to remove the black plastic top from the unit. Using a multimeter I could trace the track on the printed circuit board which goes to the thermistor the measures air temperature (thats the one in the middle of the hot wire). By cutting this track and putting a 0-47 Ohm variable resistor in series with the thermistor, I was able to richen up the mixture ( it ended up being aroun 10 Ohms), placing a high value across the thermistor will lean the mixture. I don't know whether it is the airflow meter going out of calibration or the ECCS misreading the O/P of the airflowmeter, but anyway I now have a car with a decent idle again. The cost of this repair was less than $1.
If anyone knows a better way of calibrating the airflow meter, or has some technical information other than whats in the manual I'd shure like to hear about it.
Bye Andrew
