[16v] DPR/mixture/timing questions

[doubt at inwave.com (Nate Mellom)]

Yep, I know it's indicating full rich, which I understand, and can 
adjust via the mixture screw (which I've done).  What I DON'T get is 
why, while adjusting the mixture, and having set it to averaging .5mA, 
it dropped to 0.0mA (full rich) with no input from me, never to return 
to a reading at all.  Like I said, the mixture screw was turned ALL the 
way righty richy (originally showed 0.0mA), and I leaned it out and had 
it good.  Still revved crappy, but then blammo, 0.0mA.
I'll play with it some more this weekend, just out of curiousity, how 
many turns lefty leany can I expect to adjust the mixture?  I've read to 
turn it 1/8 revolution at a time, but I think when I leaned it out I was 
at least a full half turn, just wondering if I should continue leaning 
it out a full turn or more.  When I did lean it more than a half turn, 
it stumbled and would barely idle, but still reading 0.0mA.  Which got 
me thinking that the morons who worked on it before I did adjusted the 
timing with a bad O2 sensor and a full rich mixture, just to get it to 
run half-way good.
Nate

Oh, and for the record, I tested my DPR for resistance, (Bentley spec'd 
18-22 ohms as acceptable), and mine tested out at 18.2 ohms, I replaced 
it with a used boneyard DPR which tested out at 19.4 ohms)

One thing I didn't think of, while testing contunuity at the O2 sensor 
control module, was to turn the ignition on.  The other electrical tests 
shown in the chart specified whether or not to turn the ingition on or 
off, this one didn't.  Maybe that'll be my next step.


C Boyko wrote:
> I can't speak to the continuity tests, as I haven't done them, (and
> obviously wiring is pretty important...) but both DPR and O2 sensor are
> indicating full rich, on the O2 rich reads high, DPR reads low IIRC. (since
> DPR current is just an adjustment value, and it doesn't need to adjust
> anything if it's already too rich) What do your plugs look like? I'm just
> wondering what happens if you turn your handy Allen key "lefty leany" (not
> "righty richy", LOL) on that airbox mix screw. Is it possible that the DPR
> just can't do anything about the rich condition? 
> 
> Cathy
> 
> 
>