4kq bad mileage

[Huw Powell]

> My 86 4kq is getting really crappy mileage, but it runs well. It'll do about
> 430km (265miles) on 58litres (15.3US gallons), so about 17mpg.
>
> So far, I've plugged vacuum leaks, new intake and exhaust manifold gaskets,
> new injector seals, adjusted CO back to spec with a sniffer, cleaned ISV.
> The car runs well, so I can't really complain, but my Audi guru mechanic
> friend (and the list here) seem to think I should be getting 25-28mpg. I
> used to, til I fixed a wire in the starter to enable the cold start
> inj/thermo-time switch to work. Think they're on all the time?
>
> Another hint is that the temp gauge doesn't rise much over 70C, still in the
> cold range, and the heater doesn't blow that hot, but the rad fan will cycle
> eventually.

My first thought was OXS gone bad, and running rich all the time... then
I read the heat/temp stuff.  I'd guess theremostat stuck open and the
motor never gets warmed up properly (or at least spends way too much
time too cool), runs rich and wastes fuel.

> I'm going to change the thermostat tomorrow, but would that make such a
> difference?

You'll know fairly soon now!  You should expect 22 to 28 mpg, depending
on luck and driving style and demands.

--
Huw Powell

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

http://www.humanthoughts.org/