Re: QTC/urQ: Running Rich

[Orin Eman <orin@wolfenet.com>]

> duty cycle was less than 5%!  The ECU is working fine I disconnect the temp
> sensor and the OXS and the duty cycle behaves as the IST dcuments describe.
> I pulled the plugs and they were consistently black from running rich.  I
> got a set of plugs cap and rotor and OXS and Tom Nas and I installed ... no
> change.  When the car is running at higher RPMs it seems to clean up ... the
> duty cycle comes up to 50%.  We found that one injector had backed out a
> bit, but the Viton seal was still supple ... so I put it back in.  

> >From my Sun 75 the CO seems to be in spec, but the HC is excessive.  I have
> yet to put a fuel pressure gauge on the thing to try to figure it out ...
> but I thought I'd post my experience to see if there were any thoughts ...

Duty cycle at 5% indicates the ECU is trying to lean it.  Therefore,
I would assume it isn't misfiring since that has the opposite effect -
the ECU sees the unbunt mixture as lots of O2 and thinks it is lean,
resulting in a high duty cycle.

What controls the mixture - fuel distributor via frequency valve,
_control pressure regulator_, mixture screw, air flow plate.

I'd check the fuel pressures next and that the air flow plate
isn't sticking.  Also, when you do get the duty cycle to 50%,
can you hear the frequency valve buzzing?  Perhaps it is stuck.


Orin.