850 glt 2.5 20v bad mpg

[Cypher007]

hello,
quick question or maybe a long one :)

i have a 850 2.5 20v it is not the most economical car in the world, is there any way of increasing the mpg as if i accelerate any slower tractors will overtake, i also cruise at 56mph. ive considered the following:

1) fitting bosch silver plugs.
2) fitting either a itg or bmc air filter
3) de-cating the exhaust
4) fitting one of those ecotek valves
5) fitting a ecoflow magnet (dont think this works myself, but im desparate)
6) going lpg (but the install costs are incredible and the f**kin government wont give out grants on old cars (which are usualy the ones which would benefit the most).

also ive noticed the car hunts a little when ticking over, is this normal?
it is also hard to start from warm at times. and last question should the cooling fan run on when you turn off the ignition as mine dosent and should there be a square piece of plastic behind the front grill (like the old days when people used to put bako foil on the front grill in the winter).
p.s. has anybody got a wiring diagram or pin out for the volvo 708 stereo and amplifier (which is behind the centre console).

[liuleichan]

>hello,
>quick question or maybe a long one :)
>
>i have a 850 2.5 20v it is not the most economical car in
>the world, is there any way of increasing the mpg as if i
>accelerate any slower tractors will overtake, i also cruise
>at 56mph.

The 56 mph thing tends to be something of a myth, now. I would necessarily assume it's the most econmical speed for your car (drag squares with speed).

>ive considered the following:
>
>1) fitting bosch silver plugs.

If the spark plugs are good, and not fouling, I wouldn't worry about them. If you look at the expensive plugs, how long would it take to recoup the additional cost.

>2) fitting either a itg or bmc air filter

If your air filter is clean, and not obstructing, an expensive one, will be difficult to justify on fuel consumption grounds.

>3) de-cating the exhaust

You may need to make other changes, to make the engine work OK like this. You'd also have to be reasonably happy your car would pass MOT emission tests, without it (not *impossible* for some cars).

>4) fitting one of those ecotek valves

There's no such thing as a free lunch. I'd be at least a touch concerned about consequences. And factor in the cost of the device, against how long it would take to recoup via fuel savings.

>5) fitting a ecoflow magnet (dont think this works myself,
>but im desparate)

You'd have to be... ;-)

>6) going lpg (but the install costs are incredible and the
>f**kin government wont give out grants on old cars (which
>are usualy the ones which would benefit the most).

You'd have to keep your car a few years, and do a fair number of miles for it to make a great deal of sense - unless you can get a grant, or it's negligible in the cost of either a new or used car.

>also ive noticed the car hunts a little when ticking over,
>is this normal?

I wouldn't have thought so.

Other things to consider, for a few of the things you've mentioned - they would, no doubt, be considered as modifications from an insurance point of view, and possible attract a rise in premium.

In general, good maintenance - regular servicing, oil changes, filter changes etc... correct tyre pressures - regularly maintained. Not carry additional loads, or stuff in the boot, that you don't need. Roof racks. Style of driving - planning ahead, no harsh accelerating or braking - ie a smooth driving style. Reducing short journeys ie if it's possible to walk instead. I have noticed that some drivers, often labour the engine in too high a gear, too (I've noticed a lot of taxi drivers do this), no doubt on (often) the bogus assumption that it will definitely reduce fuel consumption. Choosing the right gear for the situation, in good time (ie smoothly) is much better, too higher gear can often cause higher fuel consumption, and other engine issues.

Addressing these points / issues are probably most likely to get the most fuel economy that you can (I'm not necessarily suggesting that you fall foul of any of these - just things to consider), really. Otherwise you are considering things like lpg (reducing fuel costs, as opposed to consumption), which are expensive (relatively) and would take quite a bit to justify on a cost basis.

Modding your car, in general, I think is unlikely to help much where fuel economy is concerned, and will probably just drain your wallet, for no gain. It's a reasonable size engine, so is never likely to be as economical as a smaller engined car. If it really is that much of a priority, you may have to consider a more economical car - a leopard can't really change it's spots.

Lei Chan

[Cypher007]

thanks for the advice.
on a more personal note (and this may sound stupid) are you from China or Hong Kong. i only ask this as my girlfriend is HK and i spent 3 fantastic weeks in HK, living with her family in a small but cosy flat.

May be stating the obvious but what is "bad" mpg ? has it suddenly gone bad, or is it not what you expected ?

[Simon Linton]

My 850 GLT saloon gave late 20s mpg around town and early 30s on motorway trips - it was an automatic and I didn't hang about significantly.

If yours is about there, then there is nothing you can do except follow Lei Chan's excellent advice; tinkering may well make matters much worse.

The 850 is a big, heavy, not very aerodynamic car - if you want better economy, you'll have to buy something else.

Just to make you feel better, my 850R saloon gives early 20s on the motorway and mid teens around town - on super unleaded!

[Cypher007]

apk
the mpg is not what i expected especially as simon states he gets early 30`s and im getting 28 at 56mph also he says he gets late 20 around town im getting 18, and im driving it very steady. what is simon doing im not (eg. mods driving style).

Hi,

Just so you have something to compare to I have an 855 GLT 2.5 20V.

If I'm careful I can get in the region of 24-26 mpg if I drive normally (which is probably a little quicker than most).

If I have a bad week (ie always late) it can get as low as 22ish.

When I'm spending loads of time on the motorway, even if I'm being a little illegal the mpg is seldom below 26.

I struggle to do a real economy test because my car does sound rather glorious when provoked!

However, my car is completely standard, but has had over 130000miles of volvo servicing. Although the economy isn't great, and servicing really does cost it's hard to think of a car that is such good value when you consider what it cost to buy (2nd hand).

It's an auto so I don't have to worry about being in the right gear.

Anyway, from my experience it sounds like your mpg is a bit on the low side. I'm assuming yours is manual, and there are tips to drive a manual more economically above. The hunting when idling isn't normal though. Perhaps there's something not ok with your engine management.

I hope this helps.


Regards, John


M reg 850 GLT Estate 2.5 20V auto.

[noiseboy]

I know that this is no concellation - but you could always cheer yourself up at the knowledge of my 17.1MPG from the T-5R. }>

Regards,

Phil :-)

Phil you need to learn there is something between the on/off position of the accelerator :) :)

[Simon Linton]

That's what it is, then...