Bad fuel economy

[saintjamesy89]

Hello all Citroen Folk.

I worked out my mpg over the last full tank, and I got a miserable 33mpg . Almost all of those were motorway miles at the speed limit. My BX is a 14TGE, and until Richard bought it a month or so ago it had been stood for a few years under a tree.
I would really like it to run better, be more powerful and more economical as it's none of the above...

I have replaced the spark plugs, HT leads, air filter, alternator belt and HP pump belt. I check tyre pressures weekly and the brakes aren't binding.

I have also noticed the battery is either knackered or there is a wiring issue somewhere - the battery sometimes goes flat, once or twice over night, and the headlights are always dim at the moment. The terminal connections are nice and tight

It doesn't run well, it's hesitant and jerky on part throttle and has no top end power but lots of low/mid torque. It makes a lovely growling noise! Almost sounds like it's misfiring/running on less than 4 cylinders (all 4 old spark plugs were obviously in use though when I replaced them).

The cambelt needs changing, although it was done before it was taken off the road, the bearings are noisy and the belt itself must be 2/3 years old.

Could these problems have a common cause? I have a 32/34 z2 carb i'm going to fit on wednesday, (and will be properly tuned by a magical carb-man I know) and a new distributor. I'm pricing up batteries atm. Hopefully these new things will help me out a bit.

Any there any TU3 common problems I should be aware of?

Thanks everybody.

[citsncycles]

33mpg does sound a bit low - I have to be fully laden, including 3 bikes on a rack on the back & running at 70mph to use that much fuel in my 14!

I'm afraid I'm not an expert on these new fangled BX's (this is the most modern car I've ever owned!) but it sounds like it does need a tune up. Mine is running the standard carb and in 4th will still be accelerating at 70mph. There is no jerkyness, and only a slight flat spot when very cold.

I have in other cars had an occasional misfire that only happens under load, so the offending plug doesn't necessarily show up when checked. As you've changed the plugs & leads it may be worth checking the distributer cap.

To be honest, I think the work you are doing should cure the issues, & I'd be interested to see the outcome, as in theory the twin choke carb should be both more economic & more powerful.

I'm not sure if it is the correct battery, but the one in my car is the same as fitted to 2CV's, and is coping fine with the cold weather. I can get these batteries locally for around £30, but needed to shop around a bit to do so.

[MULLEY]

70mph in a 1.4, its revving away isn't it? TBH that's what i reckon is all you're going to get, drop down to 60mph & then you might get high 30's. I know a few on hear reckon they can get 40mpg, they must drive very slowly to get that. Perhaps a little bit of fettling/tuning might get a couple more mpg but not a lot more i would have thought.

If you want better economy, then diesel is the only way to go i'm afraid.

[citsncycles]

I have managed 40mpg, but the car was lightly laden, and I was doing 60-65mph on motorway & dual carriageway - not my usual driving style

The 14 seems to be best suited to A & B roads, where you're forced to drive more slowly, & thus more economically.

I also like the relatively low purchase price, the cheap tax & the light nose weight, whivh I think benefits the handling!

[scarecrow]

Mine does 40mpg @ 70mph Min. on the motorway with 2 adults a child and a dog. Drops down to around 34 going very easy around town (if not stuck in traffic). Cold weather is different because of the need for choke.

I love the little 14 because the car feels so much more balanced compared to the diesel. For me the only real advantage of the diesel is that I trust it more than petrol

[Stinkwheel]

I cant say what you should get, but i can tell you what i get in my 14 TE St Tropez.

At 70mph on motorway 38-40mpg at best. Any faster and it canes the fuel, the 5th gear is too short and its just revving too high, hence poor consumption.

Daily on my commute for about 160miles a week it will do approx 30 mpg average. Considering on the same commute a 2CV will only do about 38mpg average then its not too bad, as we all know a 2CV can do 55mpg at 65mph on the motorway.

Contrary to popular belief these 14's are not economical, but they are nippy and light and fun and very capable despite their engine size. If you want economy in a BX you have to go diesel flavour. (hence my old 17RD coming home to northants from kent on only a tenners worth of derv)

So basically what im saying here saintjamesy89 is that your car doesnt sound far wrong, service, tyre pressure and a lighter right foot will see you up to slightly better (and what i consider normal for a 14) figures.

[saintjamesy89]

Thanks for all your inputs guys. @Stinkwheel, I did notice the drive ratios are very short, it sounds like its revving 4000rpm just doing 70!

I have tried driving with a light right foot, but with the hesitance and jerking, it's accentuates the problems and you end up kangarooing, once you put your foot down a little bit and accelerate it's ok.

I drove to uni at 60 this week (A303, M3, M25, M40 and i'm there =150miles) and used 3/8 of a tank, will be interesting to see what mpg that will be once I fill it up again.

Oh and I haven't quite got the hang of the manual choke yet! I keep pushing it in too early and stall. All my carburetted cars have had automatic ones so far.

I will let you know how I get on, i'm really hoping it will get better or I might have to go diesel, or just get my arse in gear with my astras engine transplant. I'm not a fan of diesels generally...

[Tim Leech]

Gearing on the 1.4 is about 19mph per 1000 so at 70 its about 3700

[saintjamesy89]

Well there you go then Tim! Not a bad guess eh?

[MULLEY]

You could always lpg it

[scarecrow]

Choke is a nightmare dude. We've been so molly-coddled by auto chokes that it's easy to forget that you've got to progressively feed it back in until warm. It takes about 5 minutes driving for mine in the morning. I've usually just about pushed it all the way back in by the time I've reached my destination In the summer I then have to contend with the hot-starting issues - haha. Who wouldn't want a BX?

[saintjamesy89]

I know scarecrow, I usually do very little town driving thankfully as it's awful around town when cold!

What would the logistics be for installing LPG on a 14? Bet it would be far too bloody expensive though.

[scarecrow]

From what I understand it could be blooming dangerous on a Carb engine - so you might need to convert to a TU injection engine before you add lpg

EDIT1+2: I'd just go the way of the Weber - that's my plan. Then keep the car for summer driving only.

I heard on the TV this evening that some authorities have been adding mole asses to their grit to make it stick better! What next, squirrel tongues?

[DavidRutherford]

From what I understand it could be blooming dangerous on a Carb engine

LPG on a Carb engine is actually a lot easier than on an injection engine, and if set up properly is safer than petrol.

The main thing to consider when looking at LPG is how long you're going to keep the car for, and whether you'll make back the installation costs. Installing LPG can cost anything from a couple of hundred quid to two grand, depending on if you install it yourself or pay through the nose for someone else to do it.

[saintjamesy89]

How easy would it be to do a DIY LPG conversion on the TU?

Principally it seems fairly straight forward, oh wait, no it doesn't! I know very little about how carbs work, so would get stuck or would at least need help there. The rest however is just the tank, routing piping and fixing??