Too much fuel consumption

Anything about BXs
bxdimitris
New Member
Posts: 1
Joined: Sun Nov 18, 2018 9:51 am
Location: Thessaloniki Greece (SKG)
My Cars: BX 1.4 Injection KAT 1991/Xantia 1.8 16V 1997/Xantia 1.6 2000/C5 2000cc Exclusive 2007/C5 1.6 THP Exclusive 2009

Too much fuel consumption

Post by bxdimitris » Sun Nov 18, 2018 10:09 am

Good evening and greetings from Thessaloniki Greece, i own a BX 1.4 i kat KDY engine and i need daily 10 Euros unleaded for 60 kilometers, the price of unleaded is 1.50 Euros/liter. I already changed the fuel pipes the Monopoint, the main body of distributor, the Lamda sensor but again too much fuel.
What is the solution???? :cry: :cry: :cry:

Kaapelimies
BXpert
BXpert
Posts: 189
Joined: Wed Feb 10, 2010 9:01 am
Location: Hollola, Finland
x 6

Re: Too much fuel consumption

Post by Kaapelimies » Sun Nov 18, 2018 5:07 pm

so where do you drive (city, highway, mountains) and how many liters/100km?
BX 4x4 estate, several BX Van's and some more normal estates in Finland.

User avatar
jamescarruthers
BXpert
BXpert
Posts: 401
Joined: Wed Nov 07, 2012 2:11 pm
Location: Cambridge
x 6

Re: Too much fuel consumption

Post by jamescarruthers » Sun Nov 18, 2018 5:30 pm

Unfortunately, we didn't get the monopoint fuel injection 1.4 in the UK so you're chances of getting help are, unfortunately, slim. I would say though that there must be a way of tuning the mixture with this system so maybe look in to that. For example, setting the idle CO mixture might be a good place to start, if such an option exists on your engine.
1987 Volvo 480 ES
1992 Renault Master Mk. 1. Machzone Chateau camper. 2.0 LPG

Previous BX's:
A966 XRL -- BX 16 TRS
H767 BEG -- BX 14 TGE
B316 AMP -- BX 14 E

User avatar
Jaba
1K Away
1K Away
Posts: 1349
Joined: Tue Jul 05, 2005 7:54 am
Location: Usually in the garage
x 10

Re: Too much fuel consumption

Post by Jaba » Sun Nov 18, 2018 11:34 pm

That works out at about 11l/100k or 25mpg. So its quite high, depending on usage and driving style. The mixture is controlled by a lambda sensor so I dont think it is adjustable.
What about the air filter or the mixture enrichment for cold starting being stuck on. Does the engine start and run well if not a sick engine can use a lot more fuel.
Is the thermostat stuck open perhaps causing the running temperature to be low. Just a few thoughts which may or may not help.
The Joy of BX with just one Citroën to my name now. Will I sing Bye Bye to my GTI or will it be Till death us do part.

User avatar
xantia_v6
BXpert
BXpert
Posts: 152
Joined: Wed Dec 16, 2015 6:13 pm
Location: here and there
My Cars: Peugeot 308 CC
Citroen XM V6 ES9
Citroen Xantia V6
Jaguar XJ-S V12
x 18

Re: Too much fuel consumption

Post by xantia_v6 » Mon Nov 19, 2018 2:13 am

The Bosch Mono-Jetronic injection system http://what-when-how.com/automobile/thr ... utomobile/ is a very primitive system. It has no sensor for measuring the manifold pressure or air flow, relying on signals of engine RPM and throttle position for determining fuelling, with medium-term correction form the lambda sensor.

This makes the system very prone to over-fuelling, as any engine fault (or wear) which causes the throttle to be opened a little further will cause an increase in fuel consumption.

A fault will either be one that causes the correct fuel mixture to be burnt inefficiently, or one which is causing a rich mixture to be burned. Monitor the lambda voltage and see whether it is generally indicating rich or lean. This should allow a number of potential faults to be eliminated.

Kaapelimies
BXpert
BXpert
Posts: 189
Joined: Wed Feb 10, 2010 9:01 am
Location: Hollola, Finland
x 6

Re: Too much fuel consumption

Post by Kaapelimies » Mon Nov 19, 2018 3:40 pm

I would first check the brakes, especially that the parking brake lever in the front brake saddles moves free and frees the parking brake fully.
BX 4x4 estate, several BX Van's and some more normal estates in Finland.

User avatar
Kitch
Over 2k
Posts: 6185
Joined: Sun Jul 03, 2005 9:36 pm
Location: Fareham, Hants
x 47

Re: Too much fuel consumption

Post by Kitch » Tue Nov 20, 2018 9:28 am

Should be getting 34-36mpg or so from one of those. The SPFI version of the TU3 is pretty good on fuel normally.