Increased Fuel Consumption - 3.9 V8 D1 Auto

[KevI]

1997 model 230,000 km. Usual average 15-16 l/100 km. Over last few months increased to about 20 l /100 km.
Would appreciate suggetsions as to where to look firstly.

[PhilipA]

1 Clean MAF with electronic contact cleaner spray into small hole .
2 Check vacuum advance by sucking on hose and seeing if it sticks on your tongue. If no suction replace vacuum advance
3 check centrifugal advance by seeing if rotor turns a little bit then springs back. if not remove rotor and screw underneath and drip oil down.
4 check resistance of temperature sensor to see if it below 400 Ohms at operating temp. If not replace temp sensor
5 note position on gauge of temp at operating temp. If down near blue segment change thermostat.

That is a good start along with new plugs , leads, rotor and dizzy cap. make sure you get a genuine "Lucas " branded rotor. have you EVER replaced the dizzy cap? they are wear items and should be replaced every 160KK or so.
Regards Philip A

[KevI]

Thanks for the suggestions. I should have also mentioned that the engine is fitted with a Unichip.
I can't recall ever having replaced the distributor cap.

[PhilipA]

Well forget the vacuum advance bit if the unichip has taken it over, but the rest is still valid.
While some on the forum say Unichips lose their map, I have not found this to be so, as I had mine tuned after 2 years and the original maps were still there and going strong.
Regards Philip A

[It'sNotWorthComplaining!]

It could even be something simple like a dirty air filter, I presume you would have checked it though.

[Gooner]

20L /100kms is what I get driving like a princess around town.
And thats after all the stuff suggested above. I get it down to approx 16.5L / 100kms on highway cycle. They're all different I suppose.

[Tank]

20L /100kms is what I get driving like a princess around town.
And thats after all the stuff suggested above. I get it down to approx 16.5L / 100kms on highway cycle. They're all different I suppose.
Craig...a Princess! never, Regards Frank.

[nsgnomad]

I should have also mentioned that the engine is fitted with a Unichip.

The best I have been getting is about 18 -19 L/100km on highway from my '96 D1 3.9 auto, so your 16 you were getting previously looks pretty good. Can you tell me more about the Unichip? What does it improve and approx how much is it?:confused: