4kq bad mileage (still!) (longish)

[Huw Powell]

> > The one you are looking
> > at is a negative temperature coefficient (NTC) switch, in that its
> > resistance varies with temerature.  This tells the ECU whether to run
> > rich on the cold start "map," in open loop, or to go into closed loop
> > and let the OXS signal determine mixture.
>
> Can you adjust CO in open loop?

No.  Well, you sort of could with a CO meter, but if the car is in open
loop you can't expect the best emissions anyway.  In closed loop you are
supposed to adjust for minimum CO, the way top approximate it is control
pressure reg. current oscillating around 10 mA.

> If so, does the computer even bother looking
> at it?

nope.

>
> The ground wires at the intake were clean and tight a couple of months ago.
> I'll check them and the ground wire off the sensor again. Is the temp sensor
> running a double ground, one through the rad hose flange, and the other by
> wire to the intake ground post?

I can't truly remember... but it might only be the coolant gauge that is
grounded to the flange.  Might be nothing, too, remember when I
"worried" about it I wasn't "fixing" anything, probably just screwing
around...

--
Huw Powell

http://www.humanspeakers.com/audi/

http://www.humanthoughts.org/