33 1.3 (after restyling series) fuel consumption ramped up

[Keith Walker <100662.3423@domain.elided>]

>>A few days ago, I've seen that my 33 1.3 IE started to "drink" a lot more
fuel than it ever did before.<<

It is likely that you are correct that the lambda probe is causing a
problem,
but maybe not directly. It should be easy to check the lambda probe using
a voltmeter over the sensor wires. One pair of wires should be for the
probe to return a reading, and the voltage over these wires should
vary.

If it is not a faulty lambda probe then check for air leaks. For example if
there is a leak into the exhaust before the lambda probe (and on the 33
there is around 1.5m of exhaust before the probe) then this will let
oxygen into the exhaust. This will cause the probe to give a false reading
as it will think there is too much oxygen coming in the exhaust gases
from the engine. To compensate the ECU will inject more fuel

Also it is worth checking all the connectors to the engine. For example
there is a vacuum line from the intake manifold to the MAP sensor
(senses air preasure), and there is also a line to the fuel preasure
regulator. If this line becomes disconnected then the fuel preasure
will rise.

The ECU will compensate for many faults based on the readings from
the lambda probe. However if the readings go sufficiently out then
the ECU will probably decide that the lambda probe is faulty and
so just use default settings (a sort of "get you home" mode).

It is also possible that the car will run fine until power is lost to the
ECU. On a late 1.7IE 33 we had it ran fine until I changed the cam
belts. I disconnected the battery when doing this (to prevent expensive
mistakes!), and afterwards the car ran badly, using alot of fuel. The
problem did turn out to be the lambda probe, which had probably
been faulty for some time. On the late 1.7 IE the ECU is quite
crude initially, but programs the fuel map as the car is driven, based
on the readings from the lambda probe. Even with the probe not working
the ECU had a good "map" to use. Once the battery had been disconnected
the ECU had to run on its default settings.

All thebest

Keith

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