poor fuel consumption

[Freepress]

I have a 1.6 trs auto with a weber 32/34 carb, am having poor fuel consumption, checked timing Ok plugs running a bit black/grey have weaked mixture, any more ideas

[Philip Chidlow]

When you say poor fuel consumption, what sort of figures are you getting? The 16 auto is not exactly renowned for its economy... my 16TGS auto used to get 20 mpg (14 litres per 100 kms) ('urban' and barely managed 30 mpg (9.3 litres per 100 kms) over longer journeys.

[Kitch]

My 16 auto was dismal on fuel. As I understand it, they all are! Word has it the 19 is actually better because the engine doesn't have to work as hard.
The difference between an auto and manual with the same engine wasn't subtle. The 16 did 42mpg average on a long run, the auto never bettered 25mpg and it had a brand new weber carb fitted. It was in good mechanical shape.

[Tim Leech]

Weird I get 40+ out of mine on a run, and isnt noticeably thirsty, and thats on that shite solex.

[mat_fenwick]

40mpg sounds very impressive Tim!! You sure your speedo isn't in km? Is everyone else whizzing past you?
I've never liked autos with small engines, admittedly I've never driven a BX16 but I feel that they're more suited to a big lazy engine. Still, each to their own...

Freepress, has the consumption got worse all of a sudden? Which would suggest something is wrong, rather than just par for the course.

[kiwi]

I have a 1.6 trs auto with a weber 32/34 carb, am having poor fuel consumption, checked timing Ok plugs running a bit black/grey have weaked mixture, any more ideas

Depends on what you call poor fuel consumption and how you have checked it?

Brim to Brim (not the 20 quid rough guess lark) over a few trips of similer driving conditions? Grade of fuel used and remembering the BX was introduced before unleaded became the fashionable grade have you retarded the timing to use that lower octane?

Next is have you checked the brakes? Do the wheels rotate Freely?

Tyre Pressure are they correct?

You got a roofrack on?

You have Aircon and use it all the time?

Tyres are they the correct size? If not then you could have a speedo error that makes the fuuel consumption look heavy or even have a faulty speedo with an error (Its possible I have a BX with uncalibrated speedo/odometer and one with wrong size tyres)

One that I have a question on relevance myself is the exhaust system! I have two BX19 Manuals and differant fuel consumptions on each. The car thats heavier on the juice also has a speedo error (which calibrated with a GPS) and aircon (which is rarely used) but also has a tinkering from what sounds like a loose baffle in the muffler.
Yet theres a 1km per litre differance in fuel consumption even after the calbration...hence I mention exhaust.

In theory with the open road driving at 100kph I do on open roads I should be getting good consumption! I dont because of the twisty and undulating (Hills) I drive, undulating in that the altitude changes by up to 800metres on a 50km Trip. More closer to urban style driving!

Unfortunate that the official figures are done undder perfect test conditions with 97 octane (4star) So expect slightly lower

Having an Auto 16 ironically has a better urban economy than a open road economy than a manual. According to the Goverment fuel stats sheet I have in my handbook.

[DLM]

On another tangent, check the rear brakes aren't binding/stuck - many 16 autos have pootled around doing low mileages and don't carry a load in the back to bring the rear brakes into play very often. As a consequence, discs rust and things generally gum up in the caliper area.

Same with the front brakes (minus load issues) though they normally squeak away if binding. Is the air filter recent, and are the engine breather tubes clear? Is there a lot of emulsified oil in the wire gauze at the top of the oil-filler cap from short journeys?

I am inclined to agree with Kitch's comments, and even manual 16s aren't the world's most fuel-efficient cars unless doing longer journeys regularly.

[DavidRutherford]

Weird I get 40+ out of mine on a run, and isnt noticeably thirsty, and thats on that shite solex.

But yours is a manual is it not?

[docchevron]

It was last time I saw it!

[Freepress]

sounds like it is not too bad after all i am getting around 28 mpg, thanks for your help
another one for you on tickover i get a consistant knock once maybe every 10 secounds sounds like it is coming from the hydraulic pump is this normal or anything to worry about

[LiverMatt]

I was averaging about 30mpg in the winter on my 20mile commute to work in my 16TGS auto, mostly m'way.
Speaking of which, daft question from a BX owner, but is the 16TGS auto supposed to have PAS??
I'm going to hide in shame now...
=]

[DLM]

Speaking of which, daft question from a BX owner, but is the 16TGS auto supposed to have PAS?

Not a daft question. Like many car specs, Citroen's have often seemed to be decided by waving a wettened finger up to the air to feel for wind on a random day.

I don't think it did, except as an option, but probably would've been there on a TZS model. From memory, 16's aren't a struggle without PAS, but then I don't know how much extra weight an autobox might add. There'll be a flow diverter near the pressure regulator and a ram on the steering rack if yours does have PAS.

If overdue for an lhm change and filter/tank clean, then a BX with PAS might feel like it's got insanely heavy manual steering, especially when the temperature is cold outside.....

[DLM]

on tickover i get a consistant knock once maybe every 10 secounds sounds like it is coming from the hydraulic pump is this normal or anything to worry about

See here: http://www.tramontana.co.hu/citroen/sus ... ension.php
for more info.

Sounds like the pressure regulator kicking in - if it's quite regular at 10 secs at idle and more like a click or tick than a knock, then that's what you're hearing.

This noise, if at the right intervals, is all part and parcel of the hydraulics on a Citroen like yours. It tells you something about the health of the hydraulic system on the car for suspension, brakes and power steering if fitted. If it's ticking very frequently, something needs fixing soon!

You should hear the same noise after the car rises up when starting. Also, try pressing the brake pedal at tickover once the car has risen: that will probably provoke a tick shortly afterwards.

A new accumulator sphere wouldn't hurt, but as the hydraulic components in the car age and leak-back more, "tick-time" can get more frequent than the 25-30 seconds quoted in the above website as an ideal.

[kiwi]

To give an idea of what I am getting out of the 19TRS which is better than the 19TZS for reasons stated above I am thinking (tyre size, miscalibrated odometer, aircon and probably Exhaust baffle issue)

Date Litres Total $ CPL $ Odometer KMs Kms 274642
29.9.08 23.07 45.43 200.9 274875 233 10.1
4.11.08 20 33.98 173.9 275500
20 33.98 173.9 275601
27.11.08 40.41 58.96 145.9 275629 754 9.3
15.1.09 44.22 61.86 143.9 276059 430 9.7
4.3.09 49.53 82.17 169.9 276566 507 10.2
12.3.09 36.31 58.42 1.649 276977 411 11.3
14.04.09 52.57 84.6 1.649 277565 588 11.1
30.05.09 52.53 87.15 1.699 278103 538 10.2

3461 10.22

Thats 10.22 km (6.39 miles) per litre (27MPG) average on open road running but with these twisty undulating roads even at 100kph its still not close to the "offical figures" our 1500cc auto none BX averages 12kpl.

Not sure what to blame in the quality of fuel or altitude and general road conditions certainly traffic is not a factor for me.

[Tim Leech]

Weird I get 40+ out of mine on a run, and isnt noticeably thirsty, and thats on that shite solex.

But yours is a manual is it not?

Yes it is but Ive owned a couple of 1.6s, a 1.9 and 1.9GTiAutos and driven sensibly would do 40mpg on a run, maybe that the auto cars have a higher top gear 25mph/1000rpm instead of 21mph for the manual would help on motorway journeys. Guess its down to your driving style and journey type but I am a fairly steady driver and rarely do more than 70-75mph.