Re: [DML] Fuel mixture oscillation (was "Coasting and pulsating")

[William T Wilson <fluffy@xxxx>]

On Fri, 8 Sep 2000, Grimsrud, Knut S wrote:

> By monitoring the mixture (using some of the circuits outlined in the
> back issues) it appears to me that the mixture control scheme in the
> DeLorean is not very stable and has a tendedncy to easily oscillate
> between rich and lean. This oscillation is probably the same thing
> many cars suffer from when they are cold and the idle surges until the

It is normal for all fuel injected cars to go back and forth between rich
and lean. The oxygen sensor is not precise enough, nor the fuel system
responsive enough to get the mixture perfectly right all the time. So it
is normal to go back and forth between rich and lean.

The O2 sensor will not work at all when it is cold, so the system has to
run in open loop (a preset amount of fuel, without regard to the O2
sensor) mode at first. I don't know about the K-jetronic specifically, but
it is also normal for fuel injection systems to run open loop at full
throttle and/or high RPM. (In this case you should see the mixture become
rich and stay there).