318iS fuel consumption ideas

[mark_i]

1990 318iS runs sweet as with perfect idle@750rpm and revs freely except for two issues

1/ under load, I can see exhaust smoke (only at night in the lights of the car behind)

2/ fuel consumption is none too flash @ 10km/L, approx.23 mpg with dry black soot in the tailpipe even after a run.

Which component/sensor of the Motronics would cause a rich mixture?

I'm also thinking the catalyst would be dead after long term exposure to a rich exhaust. Time for a CO check?

[Sanchez]

i get 350-370miles from a full tank driving 50-60mph 3000rpm with a little aroung the town driving as well and the odd lead foot.

[tim_s]

i get 350-370miles from a full tank driving 50-60mph 3000rpm with a little aroung the town driving as well and the odd lead foot.

lol now you're just showing off. to be fair i get over 30mpg with the 2.1 and throttle bodies/standalone.

to the original poster, get a full diagnostic done before anything else, I can do one for you if you're nearby?

[Sanchez]

but thats being really careful. probably only do that a few time. 300 is good for me.
my seat gets to london on a tank so she gets more use.

[mark_i]

Thanks for the offer Tim, Bristol is a bit too far away from Sydney.

[Brianmoooore]

Check out the engine temperature sensor for the ECU; the blue one.

[mark_i]

Check out the engine temperature sensor for the ECU; the blue one.

Thanks Brian.
By check-out, you mean replace or get clever with a resistance vs. temp evaluation?

[Jon_Bmw]

Never had an IS, but i vaugly remember reading that 2 fuel pipes quite often leak on these in the engine bay, perhaps under the inlet manifold? Sorry thats a bit hazy, but its all i remember. Perhaps worth a try if your engine bay smells a bit like a shell garage.

[Brianmoooore]

Check out the engine temperature sensor for the ECU; the blue one.

Thanks Brian.
By check-out, you mean replace or get clever with a resistance vs. temp evaluation?

Either, I suppose.
I posted typical resistance values against temperature in another thread last night, but the sensor's not very expensive to replace new.
Wouldn't be a bad idea to get the car's exhaust gasses analysed before you get to involved.

[320Touring]

34mpg caning the Sh!t out it on the Scottish run.

That does sound like a sensor fault as per brian's advice