Re: Ur-q duty cycle wrong.

[Orin Eman <orin@wolfenet.com>]

>    Once the engine gets a bit of a temp into it, the duty cycle shoots up
>    to 96% 

> This is NotGood(tm)!

>            and stays there unless I close the full throttle switch at which
>    time it goes back to 77%.

>    I tried to adjust the CO from all the way rich to all the way lean
>    (untill the engine stalls).
>    No change in duty reading.
>    Also unplugging the Oxygen sensor makes no difference, the wire is fine.
> ..........................................................^^^^^^^^^^^^^^^^

> This doesn't necessarily follow, but I believe the ECU will go open-loop
> if it thinks the O2 sensor is not working, and hold at 50%, so I suspect
> the wire is indeed fine...

> Running at 96% says the ECU is maxing out trying to enrichen the mixture.
> (by the way, there is some anecdoctal evidence that the ECU can fry its
> FQ drive transistor this way...)

> The first thing I would check is the voltage coming off the O2 sensor.
> 0.5V is nominal, lower is lean, higher is rich. From the above, you
> should see very low voltage, probably very steady.

> My guess would be either faulty O2 sensor, or low fuel system pressure.

> Look at the plugs -- do they look fouled (sooty-black)? That would in-
> dicate actually running rich (bad O2 sensor); do they look white or
> very light color -- that would be lean (too "hot"), or low fuel pressure.

> That's where I think I would start... (O2 sensors are, relatively
> speaking, cheap -- I'd just replace it on GP's...)

I'd check the plugs, cap, rotor, wires, coil.  In fact the entire
ignition system.  An ignition miss can cause this - O2 sensor senses
O2 in the exhaust - misfire means lots of O2 in the exhaust and
the ECU will think you are running lean and peg the frequency
valve at 95% or so.

I agree with looking at the plugs first.

Orin.