I have a seicento sporting S reg, SPI that does about 25 to the gallon. It's driven on urban roads, but very little start stop, and sitting in traffic.
I have changed, Lambda, temp sensor, air filter, oil filter, oil, brakes not binding, tyres at correct inflation, etc.
Some black in the tail pipe, so running a bit rich. Any thoughts were to look next?

How are you calculating the MPG?

Which temp sensor did you change?

What is the age of the coolant?

Does the heater get piping hot inside?

Cheers

D

MPG via miles run from GPS, and amount of tank fills over about two months.
Engine ECU temp sensor.
Changed about 3 months ago.
heater is nice and toasty.

Does it start OK when warm ?

Under what kind of traffic conditions?

take air filter of and start the car see if the injectors ok look for drips ect should b a fine mist i had same problum and it was just a o-ring on the injector


thx andy

Warm starts fine, no problem with cold start. No leaks of petrol I can find.
Most running is about 30-40 MPH, very few stops, and almost not waiting.

Is it servided regular?

Does it use oil?

Try petrol Injector cleaner.

Noel

GeorgeDamper said:

Does it start OK when warm ?

Click to expand...

Mines not starting when warm.. Any ides. Ive done engine temp sensor (blue one) cleaned crank temp sensor and new air filter and injector cleaner

Serviced well, but not sure about it's past. No oil used, new plugs , leads, etc a couple of months ago. Injector cleaner put in tank about 8 fills ago.

GeorgeDamper said:

Does it start OK when warm ?

Click to expand...

could i ask please about the warm start question? my seicento has a terrible
time starting when warm or hot even, i have still problems finding a short in my engine or body that is throwing up an error code,
thanks

Hi

Please try more injector cleaner I need to use more frequently that that all the time, mine does 40-55 MPG, dependeing on duty cycle and lead boot. One failure mode is that the injector is leaking slowly into the engine manifold cause the injector is not sealing, the cleaner might fix that.

If you stop the car after it is warm and remove the air cleaner the inlet should not reek of petrol, to excess.

There is a MAP sensor a vacuum tube from air cleaner to oil trap, to region of ECU. please check that the tube is there and not blocked.

Is there oil residue n the air cleaner housing?

Noel

dragging this back up because ive used 3 full tanks of fuel now and am getting an average of 28MPG

whipped the airbox front off when i got in from work and could smell fuel, i had to get right up close but it was definitely smelling of fuel.

the MAP sensor pipe is in place, there is a black valve in the line, maybe a one way thing? worth cleaning that out?

i think ill order a temp sensor as its looking pretty old, looks original anyway..

any other things to check?

I usually bin the black one way valve thing -- Cinqs don't have them.

You might try injector cleaner, but it's probably cheaper to get the injector cleaned or get another from a scrappy.

Most Cinq turbos do about 25mpg.....................