MR2 Roadster Owners Club

The Workshop => Performance Related => Topic started by: Liz on November 26, 2005, 17:06

Title: Petrol Guzzler
Post by: Liz on November 26, 2005, 17:06
 s:evil: :evil: s:evil:   Not happy at the moment, since I have been doing the 52 mile round trip again my car is  drinking petrol like its going out of fashion.

Now setting myself up here I know for being accused of driving like a granny   s:? :? s:?   - but before I used to get...

by 1/4 tank - done 90 miles
by 1/2 tank - done 180 or there about
by 3/4 tank - done 270ish, petrol light generally came on around the 330 mark if I let it get that low.

I appreciate that I now have the unichip, but I thought it was meant to make the car run more efficiently?

Today when I left for work the mileage was on 175 at half a tank, but the time that I had travelled into work the level was sitting at just over the 1/4, just home and it has gone down to just past the 1/4 level, only travelled 50 odd miles in that time.  The tyre pressures have been checked and they are ok, nothing appears to be binding. and I am sure that I don't have a leak, any ideas anyone, I have searched honest, I can find a post I did about this ages ago, but that was pre-unichip.
The roads I travel are mainly 50-40mph and 70mph, very little urban driving, ok I hang around the 80mph mark normally (but I don't endorse speeding). I can honesty watch the level of the petrol go down.

I may as well change cars now to what I want to get as the fuel consumption is about the same!  Any ideas anyone - especially those with unichip?  Thanks in advance.
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Post by: aaronjb on November 26, 2005, 17:25
Sounds like you're getting about the same mileage as I do now - I've only managed 300+ on a tank when sitting at 60ish on the motorway for a long (half tank plus) run..

Are you filling up at the usual station, or have you changed?

I've been keeping track of my mileage recently (watching the pennies and all that), and I was getting between 33 & 37mpg and it was costing me between 11 & 12p/mile, paying 91.9p/litre at Murco..

So I filled at a Texaco station on the way home from work - 88.9p/litre, so that should be cheaper, no? Except I only got 30mpg on that tank, so it actually cost me nearly 14p/mile...
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Post by: Liz on November 26, 2005, 17:37
This tank is Tesco 99RON, I normally use Optimax, but to be honest - not noticed much difference between the two in that the level goes down at about the same rate.  I hit a bump the other day, I might check my petrol tank hasn't got a huge dent in it or something!!
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Post by: LeeUK on November 26, 2005, 18:03
Blimey Liz, don't knock it, I'm getting 200+ miles per tank.  I think it's mainly to do with the induction kit, fuel/air mix etc.  More air drawn in, and therefore more fuel burnt too!
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Post by: darrenjuggins on November 26, 2005, 18:06
Hi Liz,

the milages your getting sound pretty good to me, I've never got better than 330 out of a tank (I do use my aircon all the time thou).

This was achieved after I *cough* had to slow down a little after a little brush with your colleagues on the M18 *cough*.

I was amazed what smoother driving achieved for my MPG - nearly enough after a few tanks to pay for the *cough* fine!

The weather is changing at the moment and that will cause the engine to take longer to warm up, etc, etc so I'd not worry to much.

Cheers

Darren J
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Post by: filcee on November 26, 2005, 18:08
Two things spring to mind.  Petrol takes up less volume in colder temps - though whether this is enough to make the gauge reading change I don't know.  Secondly, colder air is denser air, therefore more oxygen is being drawn in to the engine, which requires more fuel to be burned to maintain the correct fuel air mix in the cylinders.  This latter would mean higher consumption.

If it's any compensation, consumption on mine has gone up a bit too, though I have to admit that I had put that down to using the air con all the time now that winter is here.
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Post by: Liz on November 26, 2005, 19:54
Thanks for the comments guys, maybe I just need to get used to the gauge moving again, after filling it up once a month and now back to about every 5 working days, I am sure to notice a difference, but it used to be so spot on with the marks on the level.
Good points guys which you raised, I feel a bit better now!  s:) :) s:)  

I will have to lose the heavy right foot on the dual carriageway I think, but I do hate to be overtaken by Novas!
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Post by: proeliator2001 on November 26, 2005, 20:13
I was getting about 34 mpg before the cold weather and now, with headlights on all the time, heater going with demister on, its down to about 31-32mpg (which is still good IMO).  Must be the same for everyone I'd have thought.
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Post by: Anonymous on November 26, 2005, 20:51
Christ I must really drive like a very old granny....  s:cry: :cry: s:cry:    s:cry: :cry: s:cry:  

I'm getting 36-38mpg and have achieved 43mpg  s:!: :!: s:!:  on a long leisurely run to Scotland.

Also still on original tyres after 16,700 miles.

Do I have to leave the Club  s:?: :?: s:?:
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Post by: Ernie Ball on November 26, 2005, 21:06
Where you are doing your miles makes all the difference.

I do most of mine in Dublin, where traffic is horrendous.  My 4-5 mile morning commute can take as long as 45 minutes.

In those conditions, I only get around 200 miles per tank.  However, when I go on longer journeys to the country, I get about what Liz is getting now.
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Post by: filcee on November 27, 2005, 00:08
Quote from: "DavidM"Also still on original tyres after 16,700 miles.
Going off-topic, but I changed my rears after -er- 28000 miles!
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Post by: heathstimpson on November 27, 2005, 06:27
Liz have you reset your ECU since swapping the fuel you use  s:?: :?: s:?:  I also notice a drop in economy this time of year due to the colder mornings etc. I do long 45miles motrway runs to work and never get above about 33mpg so you are doing pretty well; even my diesel MPV that is suppose to average 48mpg is only doing about 37 in this cold even on runs  s:? :? s:?
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Post by: Liz on November 27, 2005, 09:00
I did reset the ECU before I started doing long runs again, but I am not sure that I got the right run first time out to train it, as its Sunday I will give it another go before I head into work today, should be a little less traffic around than normal. Apart from Xmas shoppers of course! I am glad to hear that I am not the only one that this is happening to though, not glad that everyone is eating petrol, but glad that this is normal for the time of year.
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Post by: LeeUK on November 27, 2005, 13:27
Hmmm tyres  s:oops: :oops: s:oops:  .  A trackday + maybe 8000 miles?  s:roll: :roll: s:roll:    I may have to go back to the OEM wheels  s:P :P s:P

Good think about this weather is getting the rear out of line sideways up the road in the wet and you're using no rubber!  s:twisted: :twisted: s:twisted:  Bargain fun!
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Post by: kanujunkie on November 27, 2005, 16:47
Sorry Liz got to agree, i normally get around 250miles to a tank, so if your getting more then thats a total bargain in my books, mind you i do like a spirited drive  s:twisted: :twisted: s:twisted:  

Quote from: "LeeUK"Good think about this weather is getting the rear out of line sideways up the road in the wet and you're using no rubber!  s:twisted: :twisted: s:twisted:  Bargain fun!

oooohhh cheers for that reminder, time for another drive me thinks, just had a complete laugh through the ashdown forest today, but theres always time for another quicky
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Post by: loadswine on November 27, 2005, 18:14
Don't worry too much Liz, the cold starts really hammer the fuel consumption. Like Heath, my diesel suffers big time from cold starts round town 32 ish sometimes,( mind you that is from an auto with 175bhp and 270 lbft ).
My 2 is not so great at this time of year , drops from 38-40 in Summer to 30-35 now.
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Post by: heathstimpson on November 27, 2005, 19:00
But Liz when I switched to using 99Ron Tesco super I found a slight improvment with economy.
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Post by: Liz on November 27, 2005, 20:03
Filled up with Optimax today going to see how it goes now   s:? :? s:?
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Post by: Anonymous on November 27, 2005, 21:23
Tis the reason for my Tdi - now getting 480+ driving like a looney
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Post by: Anonymous on November 27, 2005, 21:26
I had a 500 mile round trip down to essex and back this friday, I tanked up before setting off and was pretty happy about getting 180miles by the time the needle hit the ½ way mark.

I filled up again down there and the by the time it was at the ½ point again, it'd done 220

Both times i filled with regular 95 shell unleaded.

Usual round town driving i'm happy to get 100 miles to a tenner.
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Post by: Tem on November 27, 2005, 22:29
Maybe it's just the cold weather and short drives? The engine running rich all the time till it warms up...
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Post by: BenF on November 28, 2005, 00:08
Quote from: "Tem"Maybe it's just the cold weather and short drives? The engine running rich all the time till it warms up...

I think this is it - Its normal for MPG to drop a little in winter as it takes longer for the engine to warm up.

FWIW I'm getting 30-32mpg at the moment on a 25 minute/ 15 mile commute to work - part in town at a steady 30mph and part 70mph cruise. This is using 99RON Tesco fuel, and with the PE turbo getting some use too.
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Post by: Anonymous on November 29, 2005, 18:43
Since taking the chip out and running ordinary unleaded it has settled down to about 36-38 mpg although it's not as economical using a heavy right foot, as the weather is changing I can live with that, untill next year and the chip goes back in. s:twisted: :twisted: s:twisted:  

btw, the majority of the runs during the week are when Anne uses it for work, no more than 10 miles each way.  s:) :) s:)