Low mpg ?

[1993 Coupe]

I have a 2.0 16v 1993 Coupe iwth 60,000 miles on the clock.
I have worked out that town driving i am only getting 21 mpg!

Any ideas what he problem could be?

It does smell like petrol if teh car is left running and i stand behind it etc...

[scotty33]

Are there any other symptoms/problems? An ECU temp sender problem could be keeping the cold enrichment on (even when the engine is warm) but this might give hot starting problems. A faulty thermostat could be allowing the coolant to flow when it it shouldn't, would keep the engine temp low for longer, which means the cold enrichment would stay on longer.
A lambda sensor problem could cause a rich mixture, but this would give good running on a cold engine as it warms up, when up to temperature the lambda starts to control the mixture, this type of problem can cause bouncing idle/stalling problems as the idle stabiliser valve struggles to cope with the rich mixture. I pasted this test from another post:

You can test a lambda probe yourself, or have a garage do it.

locate the probe itself, usually mounted on the front of the catalyst or the exhaust manifold. You will need a multimeter set to volts/millivolts or a voltmeter.

The engine needs to be warmed up to temperature for the test to work

The lambda sensor wiring plug needs to remain connected to the car's wiring harness.

follow the wires from the lambda sensor back to the wiring connector plug. There are usually 3 wires, 2 are usually white (these are the heater circuit) and the other wire (maybe black?) is the signal wire.

At the connector plug, peel back the rubber gaiter (waterseal) and identify the signal wire.

Push the positive multimeter lead/probe into the back of the signal wire connector, the negative meter lead/probe needs to go to a good earth.

You should see the signal 'oscillating' between approx 0.2 volts rising to approx 0.9 volts. It should do this once per second. If it is slower than this, the lambda probe is still working but not efficiently.

If the reading is steady, the probe is bad. If the reading is not in this range, there may be a short from the heater circuit wires, which would result in seriously bad running. As mentioned above, the heater circuit needs to be working properly, so check the fuse is ok for the lambda probe.


If you are interested, stoichiometric fuelling (air fuel ratio of 14.7:1 which gives the most complete combustion) usually equates to 0.5 volts. The ECU is not able to maintain the mixture at exactly this mix. Instead it has to monitor when the mixture is going weak (0.2v) then add more fuel until it goes rich (0.9v) The average ends up at 0.5v.
The lambda probe is not used by the ECU, until the coolant temp sender for the ECU shows that the engine is up to temperature.

[S2AVANT]

Check the petrol pipes, I have had to change mine as they had corroded where they go behind the heat shields at the bottom of the bulk head.