Re: OXS (Frequency valve) duty cycle

[DH5481@aol.com]

Thanks, Scott - I'll fuss with it some more.  When the system didn't respond
to anything (especially the 1.5V battery through the O2 sensor input which
should drive the duty cycle to 10%) I really got down because the last thing
I need is a bum ECU.  My local parts dude lists the freq valve @ $125.00.  I
read it at 15 ohms last month, but I've never heard it buzz since I started
having troubles (and never listened before that either...). Don't know if you
can put straight power to it to check it, the Bentley guidance for checking
seems wierd to me (pg. 28.44).
   I even wondered about how much one of those Micro Dynamics rising rate
fuel pressure regulators would run in the event the ECU was bad and I just
needed to bypass the Lamda control circuit.  Anyone have experience with
these?

I picked up a new universal O2 sensor today, figuring it wouldn't hurt to
have a new one anyway.   I am reasonably certain that my problem is rooted in
control pressure via the freq valve, because the car really performs when
cold - so I'm certain the Control regulator is doing its thing and giving me
more enrichment prior to warmup.
I'll tweak the bejesus out of the idle mixture tomorrow to see if I can make
anything happen.
My next step is to disconnect battery (in order to erase everything in the
ECU), replace the O2 sensor, and try again...

At this point, I'll try just about anything...  At least it drives and gives
decent mileage, so I can't complain too much...

Dave Head
87 5KCSTQ