[Mk2] [Turbo] Bad Fuel Economy ? potential issue ?!

[JLW]

Hi Guys

So this is probably going to be the one main issue that I really need to resolve,
I never bought the MR2 turbo with the idea of having a fuel efficient car. But seeing as this will become my daily driver when I pursue a different job ( have had company cars for the last 6 years, so bikes have been my toys ) I really need it to be better then it is and I'm hoping its an issue that can be fixed.

I always run the car on higher octane petrol, wether its BP ultimate or Shell Vpower etc, typically as I'm sure your aware it takes about £40-45 quid to fill her up.

From a full tank the best I have ever achieved was 190 miles !! ( b-roads )
that was with 90% of the time driving normally and not really hitting much boost. the other 10% was maybe a handful of 1st - 4th gear hard pulls etc.

I have re-searched the issue thoroughly and through peoples advice I have done the following.

1. diagnostics check - no fault codes found
2. timing checked - found to be perfect
3. NEW denso oxygen sensor bought - fitted and not making any difference
4. TRD spark plugs & Magnecor leads fitted - no difference.
5. Hub based dyno run, showed good fueling except on top end ( as to be expected ? )

The cars running a Blitz Nur Spec exhaust, it pops and bangs on overrun quite a fair bit which Peter Gidden @ SBITS said is not normal ?

Basically my question is, is this normal MPG / economy.
what are you guys getting to a tank ?

I've been told of other potential issues being,

1. Rotor arm
2. Dizzy Cap
3. Green Coolant sensor
4. Thermostat problem

Please help, I'd love to get a little bit more then 170miles which I've just got on this current tank !!!

thanks,

Jordan.

[SonicSW20]

Start off with the basics.

What are your tyre pressures?

When were the brakes last refurbished? Do all four wheels spin freely? Can you push the car around on flat ground pretty easily?

No point tearing apart ignition / fuelling stuff if you've got a couple of sticky calipers!

[C35Rob]

190 miles out of £45 of v power (about 42L at current prices) works out at about 21mpg, not too far off the mark on short-ish B road journeys tbh.

What sort of mpg are you expecting?

[JLW]

Hi Gaz

Brakes are perfect, I serviced the callipers all round and the car recently
had a full bleed and re-fill by HM Racing. Tyre pressures are 29 front and 31 rear. always maintained there.

Hi Rob

TBH mate I wasn't sure what to expect, its just I've had soo much varying
mileage from different people. Peter Gidden mentioned he gets 250 miles to a tank. but the head guy at Rouge Motorsport said the best he gets is around 200miles. I'm not sure tbh.

[thomp1983]

Firstly when you say you get 190 miles to a tank is that measured by completely filling it emptying it then completely filling it again or just it's at 190 when the ligt comes on?

[2tmike]

This issue is really much affected by the right foot but 170 miles does seem quite low. Mine's fairly standard and gives 250 miles with normal mixed road driving and up to 300 on the motorway at 'normal' motorway speed. On the track probably 7-8 mpg if its anything like the gt4!!

[JLW]

Firstly when you say you get 190 miles to a tank is that measured by completely filling it emptying it then completely filling it again or just it's at 190 when the ligt comes on?

Hi Thomp1983

tbh thats when the needle is at the lowest mark !
the light has come on and then gone off a few times when at that mark so I'm wondering if there is an issue with the cluster. its been in and out of the car a lot of times recently !

but 190 miles is basically from empty on the needle mark,

This issue is really much affected by the right foot but 170 miles does seem quite low. Mine's fairly standard and gives 250 miles with normal mixed road driving and up to 300 on the motorway at 'normal' motorway speed. On the track probably 7-8 mpg if its anything like the gt4!!

See 250 miles and id be happy ! , at 190 miles per tank I'm really not driving hard at all !

[2tmike]

Best way is to brim the tank, drive a good distance and brim it again. Going by the gauge or warning light isn't that reliable. I can do 30-40 miles in the MR2 from the light coming and staying on but the GT4 is out of fuel almost immediately

[thomp1983]

Firstly when you say you get 190 miles to a tank is that measured by completely filling it emptying it then completely filling it again or just it's at 190 when the ligt comes on?

Hi Thomp1983

tbh thats when the needle is at the lowest mark !
the light has come on and then gone off a few times when at that mark so I'm wondering if there is an issue with the cluster. its been in and out of the car a lot of times recently !

but 190 miles is basically from empty on the needle mark,

This issue is really much affected by the right foot but 170 miles does seem quite low. Mine's fairly standard and gives 250 miles with normal mixed road driving and up to 300 on the motorway at 'normal' motorway speed. On the track probably 7-8 mpg if its anything like the gt4!!

See 250 miles and id be happy ! , at 190 miles per tank I'm really not driving hard at all !

You need to work it put from filling the tank each time the resistance range on the guages is quite big it could easily be 3-4 litres more or less whulr showing the same reading.

You don't need to run the tank to empty from filling it the first time down to half then fill it is enough. The second time you fill up to full will give you the number of litres used, divide that by 4.54 to get gallons then divide miles covered by gallons used.

Different car but our golf tdi regularly does 5mpg more than the mpg shown on the dash doing the maths with proper figures is the only way to accurately tell

[SonicSW20]

Definitely do a proper measurement before you jump to any conclusions, the gauge isn't very accurate.

Brim it, reset mileage counter (which is only accurate if your speedometer is, yet another variable), run it to near empty, brim it again, note down the amount you fill it with and the mileage you've covered.

190 miles with a £40 V power fill up at the current UK average of 114 pence per litre (http://www.petrolprices.com/) works out at 24.6MPG, which isn't that bad for a turbo on b roads.

[JLW]

You need to work it put from filling the tank each time the resistance range on the guages is quite big it could easily be 3-4 litres more or less whulr showing the same reading.

You don't need to run the tank to empty from filling it the first time down to half then fill it is enough. The second time you fill up to full will give you the number of litres used, divide that by 4.54 to get gallons then divide miles covered by gallons used.

Different car but our golf tdi regularly does 5mpg more than the mpg shown on the dash doing the maths with proper figures is the only way to accurately tell

Im not exactly sure what you mean by "the resistance range on the gauge"
do you mean that they simply are not that accurate ?

What I think I'm going to do is take a jerry can of 5 litres with me and figure out how many miles I'm getting from when the light comes on, till when it starts to splutter out of fuel. Then I will be getting the true mileage of what a completely empty to full tank can do.

Then will brim the tank and keep the receipt for all the figures and then run to empty and gauge from there and report back.

[androo007]

No way man that is not accurate.

Brim car, reset odo.

Drive at least half tank, refil to brim.

Litres filled / 4.545 = gallons.

Miles driven / Gallons filled = MPG.

Do over a full tank for true reliability.

[SonicSW20]

You need to work it put from filling the tank each time the resistance range on the guages is quite big it could easily be 3-4 litres more or less whulr showing the same reading.

You don't need to run the tank to empty from filling it the first time down to half then fill it is enough. The second time you fill up to full will give you the number of litres used, divide that by 4.54 to get gallons then divide miles covered by gallons used.

Different car but our golf tdi regularly does 5mpg more than the mpg shown on the dash doing the maths with proper figures is the only way to accurately tell

Im not exactly sure what you mean by "the resistance range on the gauge"
do you mean that they simply are not that accurate ?

What I think I'm going to do is take a jerry can of 5 litres with me and figure out how many miles I'm getting from when the light comes on, till when it starts to splutter out of fuel. Then I will be getting the true mileage of what a completely empty to full tank can do.

Then will brim the tank and keep the receipt for all the figures and then run to empty and gauge from there and report back.

No need to do that, you just need to measure from a known point, which is a full tank. As detailed above, fill it to the top, drive as normal (more mileage the better), fill it to the top again, note the amount you fill it with in litres and the miles covered. From there you can work out a more accurate MPG figure.

[JLW]

Ok Guys,

Ill do the half tank idea and report back with the figures.
hopefully this will work it out and I can stop stressing !!

Will let you know.

thanks,

jordan.

[bungral]

Just to give you an idea, I did exactly this method to work my mpg out today and it came in at 26.52mpg which was 243 miles from 41.75 litres.

100 miles of that was motorway and the rest mixed around town.

It is a lot lower than that when I just do home-work-home journeys.

[BrianUK]

FYI MR2 MK11 has a 55 litre (12 gallon) tank

So at 114p per litre you are looking a @60 quid to fill it up....

The low fuel light should come on around the 5 litre (1 gallon) mark - giving you 20 odd miles to find a garage.

Have to say I make a point of brimming my tank , and then running it down as low as I dare - and regularly put in £50+ worth in.

Keeping a check on what I use I'm pretty confident I get 26 mpg on average.

[rev3gtturbo]

FYI MR2 MK11 has a 55 litre (12 gallon) tank

True but some of that is not usable. The reserve light comes on when it takes about 40 ltrs to fill the tank.
(dont assume the reserve light will always work).

[rev3gtturbo]

... thats when the needle is at the lowest mark !
the light has come on and then gone off a few times when at that mark so I'm wondering if there is an issue with the cluster. its been in and out of the car a lot of times recently !

but 190 miles is basically from empty on the needle mark,
...

The angle the fuel gauge needle moves from full to empty is the same but what I have noticed can vary over the years is where it points when full (which obviously affects where it points when it is empty).

For some cars it will be on the full line.... for some cars it will be just below the full line... for some cars it could be way above the full line.

This last option is the worst because it means the fuel could run out before it gets down to the empty line.

I have had one car that has done all three variations over the years, but it is only noticeable if regularly fill up until the tank is full when the petrol station pump shuts itself off.

From a full tank, the reserve light starts to flicker after 40-43 ltrs have been used. For my cars it is usually 40 ltrs. Unusually it has been 43 ltrs to fill it after and the reserve light has been on permanently ever since even with a full tank.

[rev3gtturbo]

A standard power rev3 turbo should easily do 10 km/ltr even driving on fun A/B roads.

I always fill up to a full tank usually with cheap supermarket super unleaded.
Usually my 40 ltrs fill up (when my reserve light used to come on) would give 400-440 km on the trip meter.
That is 250-274 miles.

Easy 29-31 mpg.

I have had better mpg from BP super but not enough for the price difference.
I seem to get worse mpg from Shell super.

[bungral]

An easy consistent 30mpg seems high. You must have a light foot or a car eager to please!

My 2.0 Hyundai Coupe barely gets that.