Re: [DML] Frequency valve

["Walter" <Whalt@xxxx>]

I agree with John Hervey on this one. You really need an oscilloscope to
see what is going on. The signal going from the ECU to the frequency valve
is a square wave signal oscillating at 70 Hertz. (Switching on and off 70
times a second). The first thing to check for is if the signal is present.
A very cheap and effective way to do that is to listen for the frequency
valve buzzing. It sounds like a noisy fluorescent light fixture only
slightly higher pitched (70 Hertz instead of 50 or 60 Hertz depending on
which part of the planet you are on.) If you are in doubt as to whether or
not you hear it while the engine is running, get a very long handle screw
driver and hold the tip against the valve and put the handle against your
ear. The sound is unmistakable. If you don't hear that sound, then you
know you've got problems. If you do hear the sound and you are still
wondering if the Lambda ECU is properly adjusting the duty cycle of the
signal to the frequency valve, then you need a scope or a dwell meter. A
typical Volt-Ohm-Amp meter won't do this trick.

I've said too much! :)
Walt Tampa, FL