Miles to full tank
Discussion
Not that I'm overly bothered as this car is about enjoyment so I normally just fill up, drive, empty and repeat. But the last few days with the nice weather I've used it quite a bit.....3 fuel stops to be precise.
Now bearing in mind, I normally won't let it drop below a 1/4 of a tank as I don't trust the guage, then when I fill it up it won't go past 3/4's.
So yesterday I let it run down to halfway between a 1/4.......looks like I got 159 miles to the fill up, is this normal?
I'm only using Shell Vmax if that makes any difference.
Now bearing in mind, I normally won't let it drop below a 1/4 of a tank as I don't trust the guage, then when I fill it up it won't go past 3/4's.
So yesterday I let it run down to halfway between a 1/4.......looks like I got 159 miles to the fill up, is this normal?
I'm only using Shell Vmax if that makes any difference.
I'm on the continent, so we are used to count in volume per distance and not the other way.
I usually expect (conservatively) to burn around 20 litres per 100 miles (yes it's a RHD Chimaera).
It's equivalent to 22.5 mpg.
With a real 3/4 of tank, you should fill up 40 litres. And that's why I'm usually stopping for petrol after 200 miles and avoid to go beyond 250.
Are you measuring your 3/4 with the gauge?
I usually expect (conservatively) to burn around 20 litres per 100 miles (yes it's a RHD Chimaera).
It's equivalent to 22.5 mpg.
With a real 3/4 of tank, you should fill up 40 litres. And that's why I'm usually stopping for petrol after 200 miles and avoid to go beyond 250.
Are you measuring your 3/4 with the gauge?
If the gauge is only going up to 3/4 when full, it's under-reading quite a lot. It's not a big tank, 57 litres, but you should get 200 miles (which would still be under 18 mpg) unless you really cane it in every gear, or are on a track day. 
On a long journey in my last Chimaera, I'd get 250 miles cruising. I've had 5 x TVRs and only the Cerbera 4.5 was regularly under 20 mpg.
On a long journey in my last Chimaera, I'd get 250 miles cruising. I've had 5 x TVRs and only the Cerbera 4.5 was regularly under 20 mpg.
blaze_away said:
You might have an overfueling issue. It's quite common on these cars.
Causes are various but easiest way to see where thongs are at is to log some data via RoverGauge. Do you have that ?
I do have RoverGauge. Having said that, it was 12k serviced a month or so ago, I'd assume this would've been picked up during that? As this has been the case with the fuel since I've had it (mid July).Causes are various but easiest way to see where thongs are at is to log some data via RoverGauge. Do you have that ?
NordicCrankShaft said:
blaze_away said:
You might have an overfueling issue. It's quite common on these cars.
Causes are various but easiest way to see where thongs are at is to log some data via RoverGauge. Do you have that ?
I do have RoverGauge. Having said that, it was 12k serviced a month or so ago, I'd assume this would've been picked up during that? As this has been the case with the fuel since I've had it (mid July).Causes are various but easiest way to see where thongs are at is to log some data via RoverGauge. Do you have that ?
The gauge on mine absolutely flies through the first half, then moves notably slower through the second half.
I also noticed that below 1/4 full, taking a spirited right turn makes the gauge drop, and an equally spirited left turn pushes it up!
If there are baffles inside the tank, they wouldn't be along the bottom anyway, so there's a bit of slosh.
I tend to refill around 200-230 miles, though I once was telling myself I had at least another 20 miles in the tank and ran out. Thankfully I was a 10 minute walk from home, so could deal with it. I must have been driving like Miss Daisy's hot granddaughter between fills...
I also noticed that below 1/4 full, taking a spirited right turn makes the gauge drop, and an equally spirited left turn pushes it up!
If there are baffles inside the tank, they wouldn't be along the bottom anyway, so there's a bit of slosh.
I tend to refill around 200-230 miles, though I once was telling myself I had at least another 20 miles in the tank and ran out. Thankfully I was a 10 minute walk from home, so could deal with it. I must have been driving like Miss Daisy's hot granddaughter between fills...
OP sent me his logfile and it shows some curious issues.
1. The car runs very cold for an extended period from stat up
2. The MAF output is very low, At idle it runs at 0.05 (5%) vs 0.32 (32%) on a normal car
3. Idle Control Valve runs at 40% vs 25% is on standard car (just needs base idle reset maybe)
I think 1 and 2 could be major factors in the fuel consumption, what do you think ?
1. The car runs very cold for an extended period from stat up
2. The MAF output is very low, At idle it runs at 0.05 (5%) vs 0.32 (32%) on a normal car
3. Idle Control Valve runs at 40% vs 25% is on standard car (just needs base idle reset maybe)
I think 1 and 2 could be major factors in the fuel consumption, what do you think ?
blaze_away said:
OP sent me his logfile and it shows some curious issues.
1. The car runs very cold for an extended period from stat up
2. The MAF output is very low, At idle it runs at 0.05 (5%) vs 0.32 (32%) on a normal car
3. Idle Control Valve runs at 40% vs 25% is on standard car (just needs base idle reset maybe)
I think 1 and 2 could be major factors in the fuel consumption, what do you think ?
That's really interesting, makes me think the ECU will be laying on fuel if it's reading a cold engine?1. The car runs very cold for an extended period from stat up
2. The MAF output is very low, At idle it runs at 0.05 (5%) vs 0.32 (32%) on a normal car
3. Idle Control Valve runs at 40% vs 25% is on standard car (just needs base idle reset maybe)
I think 1 and 2 could be major factors in the fuel consumption, what do you think ?
Maybe the Caterham temp sensor thing would help.
I also feel like my mileage has reduced since I first bought the car (though I could be wrong), as my dash gauge usually reads around 75, whilst the RG logs give a higher number. The last log I took was a year ago, and it shows an average of nearer 83-85 in RG, and when driving in the morning it can take a good 10mins to get up to 80.
I think on my next big run out I'll take a log as per your method Frank, and will see if I can work it out.
I need to dig our your instructions for what to capture and how.
PabloGee said:
That's really interesting, makes me think the ECU will be laying on fuel if it's reading a cold engine?
Maybe the Caterham temp sensor thing would help.
I also feel like my mileage has reduced since I first bought the car (though I could be wrong), as my dash gauge usually reads around 75, whilst the RG logs give a higher number. The last log I took was a year ago, and it shows an average of nearer 83-85 in RG, and when driving in the morning it can take a good 10mins to get up to 80.
I think on my next big run out I'll take a log as per your method Frank, and will see if I can work it out.
I need to dig our your instructions for what to capture and how.
FYI The Caterham gauge sender is only for dash gauge, it has no influence on the ECU. Also I dont think there is a problem with the ECU sensor as it does record higher temps, look at the early part during warm up, its just there appears to be too much cooling happening.Maybe the Caterham temp sensor thing would help.
I also feel like my mileage has reduced since I first bought the car (though I could be wrong), as my dash gauge usually reads around 75, whilst the RG logs give a higher number. The last log I took was a year ago, and it shows an average of nearer 83-85 in RG, and when driving in the morning it can take a good 10mins to get up to 80.
I think on my next big run out I'll take a log as per your method Frank, and will see if I can work it out.
I need to dig our your instructions for what to capture and how.
If you look at the right hand side of the red line (ie the OP's car)
0 to 3 minutes it heats up from cold to 86c
3 to 14 minutes it cools down to 62c
14 to 40 it warms up to 80c
40 to it cools again to 75c
40 to 48 it warms to 83c.....would it then continue cycle around 82c ?
Maybe it really does take a hour for our cars to settle at full standard design operating temperature so for journeys of less than an hour we need to expect cool running and hence excessive fuel consumption ?
ps I'll msg you email me back and I'll send the logging procedure
blaze_away said:
FYI The Caterham gauge sender is only for dash gauge, it has no influence on the ECU. Also I dont think there is a problem with the ECU sensor as it does record higher temps, look at the early part during warm up, its just there appears to be too much cooling happening.
If you look at the right hand side of the red line (ie the OP's car)
0 to 3 minutes it heats up from cold to 86c
3 to 14 minutes it cools down to 62c
14 to 40 it warms up to 80c
40 to it cools again to 75c
40 to 48 it warms to 83c.....would it then continue cycle around 82c ?
Maybe it really does take a hour for our cars to settle at full standard design operating temperature so for journeys of less than an hour we need to expect cool running and hence excessive fuel consumption ?
ps I'll msg you email me back and I'll send the logging procedure
Hi Frank, I've got a journey planned Sunday from Somerset to South Wales, I'll try and plug it all in again and record that tooIf you look at the right hand side of the red line (ie the OP's car)
0 to 3 minutes it heats up from cold to 86c
3 to 14 minutes it cools down to 62c
14 to 40 it warms up to 80c
40 to it cools again to 75c
40 to 48 it warms to 83c.....would it then continue cycle around 82c ?
Maybe it really does take a hour for our cars to settle at full standard design operating temperature so for journeys of less than an hour we need to expect cool running and hence excessive fuel consumption ?
ps I'll msg you email me back and I'll send the logging procedure
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