Reducing fuel consumption, 2.1 dj

[JNW]

Hi.

My Villa 3 hardtop with a 5000 mile-old recon 2.1 DJ engine has just managed about 20mpg on over 200 miles, about 2/3 of that on the motorway doing 70mph or under with nothing more than two of us inside.
I was expecting something more like 28mpg. It's '92 registered with 81k on the clock. My tyres are pumped, I'm using 98/99 RON petrol, I run through a squirt of Redex and I've got a light right foot.

The electronic idle stabiliser has been disconnected and I had to turn the idle screw right in to get it down to a sensible rate. The CO (mixture) screw in the air intake bit was screwed right in, and the exhaust fumes smell quite rich, even for a non CAT engine, and there's quite a lot of white smoke. There's a bit too much oil in it, but no mayonnaise showing in the oil filler.

So I'm trying to spend my way to lower fuel consumption. LPG is out of the question (too expensive; uncertain future pricing). I've ordered a K&N air filter as a first step (£35), and I'm considering getting it tuned (by whom?)

Any thoughts?

Thanks
JNW, Bristol

[toomanytoys]

Sounds like it needs a proper service and set up..

I'm afraid K&N wont do anything on its own..
Have you looked at the filter???

Too much oil will create drag in the engine... and is not good as it can over pressurise the crank case forcing seals and finding leaks...

[kevtherev]

yes...
slow down

because at those speeds LPG is well worth considering
My LPG returns 40 mpg and it paid for itself in a year

[toomanytoys]

Oh and you'll never see 28mpg..... unless you drive really slow... 24 is about the norm, with a couple of exceptions... you may see 26.....

LPG will reduce the running costs.. = to 40mpg running cost is achievable

[Red Westie]

I agree with Kev.....70mph is just too fast if you want the best economy out of your DJ....revs wise 70 is over 4,000rpm and into the red section on the rev counter.
You are not driving a car and if you want to see 25mpg then slow your cruising speed down to 60mph.

Martin

[Ian Hulley]

yes...
slow down

because at those speeds LPG is well worth considering
My LPG returns 40 mpg and it paid for itself in a year

Agreed 100% ^^^

Who told you it would get 28mpg ? Our 2.1 on lpg does 36 > 40 to mpg (petrol equivalent) as do all the others I know. The only 'certain' things about lpg is that the engines run better, smoother and cleaner on it and that for the lifetime of our vans it will always be cheaper than fool's gold.

Ian

[ermie571]

surely that's 40 mpg petrol equivilent!! Don't be telling him 40 mpg!!

oh - get your speedo checked against a sat nav.....mine is way out. Indicated 70 is just 60 mph. I was driving round everywhere at an indicated 55-60 mph....fuel economy crap....but then the sat nav told me I was doing 45-50!!!

so, now try and keep driving speeds between 60 and 70 on the speedo, fuel economy has improved. But if yours is under reading......then you could be going faster!!


Em
xx

[tonytech]

I've got a lightly loaded tintop, If I drive very smoothly and stick around 60mph I can average 27mpg (petrol) on a long run.
Blasting it at 70+mph mpg drops to 22mpg ish.

T

[silverbullet]

When we first bought Whitey it returned about 26-27 per gallon cruising at 60 mph. Tintop 1990 'velle 1.9 DG, 3+3 seats, spoiler (might help?) skinny standard 185R14C tyres, driver and one passenger. No junk onboard.
Probably as good as it gets for petrol?

[boatdog]

the best fuel saving method i found was use my corsa as much as possible! i agree with the sat nav thing as well mines the same my speedo is always about 7 mph a head of my sat nav always do 60 on motorway as 70 just drinks the fuel

[jpennington]

You might check the throttle position switch. If that's not working then the ECU doesn't know when the throttle is closed. This makes a surprising difference to the economy. My van went from around 24 mpg to about 18. It seems the micro-switch contacts get corroded and it is permanently open circuit. You'll need a multimeter to test it.
Replacement TPSs are no longer available, but its quite easy to fit a new micro-switch.

Any idea why the idle stabiliser was disconnected? This may indicate a previous problem with the TPS; or it may be the power transistor in the control unit has failed - this is a known weak point, I had to replace mine. Again, fairly easy if you can handle a soldering iron.

I get up to 27 mpg on a long run cruising around 60-65 (on the GPS - speedo is kph ). Short trips it drops to around 22.

jp

[JNW]

Hi guys
Wow, what a great response.
I don't have rev counter, and I assumed a five-speed box and a 2.1 would be good for 70. And you can't hear the engine - it's at the back! Ha!

So how can I get some of the oil out without removing (and replacing) the sump plug seal?

What are 'skinny standard' 185R14C tyres?

Who would you trust to tune in the Bristol area?

Any recommendations for an LPG conversion? I've been offered an ex-Jeep LPG tank/kit. Should I take it and get it fitted?

What do you do with all the time you have on a long journey at 60 mph?

Thanks

JNW

[Ian Hulley]

Unless you're due an oil and filter change ... drop the oil (but not the filter) into a clean container, measure 4 litres and pour that back in. For the cost of a decent Mann W719/12 filter from GSF and a gallon of oil I'd just swap the lot, putting 4.5 litres of MINERAL 15/40 in.

We cruise at 70 on the speedo which is 64 on our satnav, plenty left in reserve to pull away and plenty of time to stop quick if neccesary. At that we get 18>20 mpg on lpg. Consider the journey as part of the holiday not travel TO the holiday.

I don't know where you are in the country (i.e. fill in your profile ) but I'd recommend Steve at Gasure near Chester for your lpg conversion and he has a branch in the South East at Elite VW. Other converters are available but Steve's the top bloke, accept no lightweight imitations

Ian.

[xpress]

I drive at 55 on speedo. that's about 50 real life, would that see an improvement in mpg or can I afford to take it a bit faster ie 10 msr? it did about 50 quid from devon to London.

interestingly, my idle cut off switch, the black lead was cut at the coil, turning the idle speed screw or co mix had no effect. now its running at low revs and very smoothly. to JNW, its hard to set it up if you don't have a reference, you can tune them by ear, like an old car, go for the pick up in revs for mixture them smooth it out and lower the idle until its all balanced and smooth.

[jim potter]

just doen 590 miles in mine at 65 when on m/way and 50 ish when crusing through the country side in dorset.. and have returned 25/26mpg.. not bad for 4 people plus luggage .. mine is also a 2.1 dj