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Re: 83 ur-q frequency valve question
I have an 83 ur-q that has a rough idle.
Ok, I know they all idle a little rough. My car stumbles while it is
idling. This stumbling corresponds with the frequency valve skipping a
beat. Normally the frequency valve is buzzing at idle. In my car every
5-10 seconds it stops for a fraction of a second. The engine then stumbles
at this same time.
Here in southern California we are beginning to see some warmer weather.
This stumbling problem changes when the car is warmed up on a warm day 80
degrees+. The frequency valve will be skipping along as described above.
Then it will then stop all together. The engine will then loose rpm's and
stumble until it dies. Usually in about 15 sec. When the frequency valve
is buzzing the duty cycle is bouncing from 47-52%. When the frequency
valve quits the duty cycle rapidly climbs to 82.3%.
Climbing duty cycle says the ECU is trying to enrichen the mixture (you
should see the O2 sensor voltage dropping at this point, since that is
what the ECU is reacting to...indicating a lean mixture).
If the FV just sporadically quits, I suspect you have a flakey connection
in the wiring, or a bad FV itself. If you can watch the ECU trying to
drive the FV with 80% duty cycle, you can almost certainly eliminate most
of the system having failed, and reduce it to the FV and immediately-
If it's heat-related, you can try just pouring cold water over the FV
assembly/area and see if that affects the behavior (if it does, I'd really
strongly suspect the FV itself!). The whole FI system gets pretty tho-
roughly baked . . .
&& and &&
I am chasing a possibly similar problem where the ur-q CIS goes from =
normal closed-loop to full-rich and then full-lean and back-and-forth =
between full-rich/lean, as indicated by the O2 meter, after lke 30 mins =
of normal operation. I now have my % duty cycle gauge on the CIS FV to =
monitor what it is doing when the failure happens, but, of course, now =
that I have it instrumented it will not fail........ I see about 40-60%, =
climbs slowly as boost increases and then jumps to 80% when the system =
goes open-loop under high boost/WFO switch.
This is pretty strongly indicative of your having "disturbed" the wiring,
and have thus "reseated" ("fixed") the offending flakey connection, so now
it works just fine. A real PITA to track and fix!