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Extremely poor fuel consumption... 19 16v cabriolet.

Reno5gtt

Active Member
After chatting to a few of you on the forum I realise my 19 16v cabriolet is using way too much petrol. So I have sat down with a pen and paper to work out exactly what miles I am getting per tank and the cost and what I should be getting.

Here it goes...

Tank specifications 55 litres / 12 gallon

Petrol cost £1.40

For the past few months I have been getting 200 miles per tank at a cost of £77.00 to fill (55 litres @ £1.40)

So per quarter tank = 13.75 litres / 3 gallon / £19.25 / 50 miles

50 miles / 3 (gallons) = 16 mpg??

So it's costing me say £20 for every 50 miles for combined driving. Even on a long run to Scotland I got the exact same miles per tank (200 - 220ish).

What I should be getting according to the technical specifications of a 19 16v cabriolet

urban driving 26 mpg (312 miles per tank)
extra urban 44 mpg (538 miles per tank)
Combined 37.5 (450 per tank)

Even saying I should be getting 350 miles per tank that works out to 90 miles per quarter so I am losing 40 miles some where along the line with only getting 50 per quarter at the moment.

Has any one got any ideas of what sensor might be faulty? Or anything other Ideas of what might be wrong?

what does everyone else get?

Cheers
 
Never filled mine up m8? but I have put 50 pound in at 139.0 a litre and I got 222 mile . Till the light came on below a gallon so I put more in due to not knowing when ready to konk out of fule . And that was going to work and back and around doors . So long trips are better for me . Plus I drive like a dic sometimes lol . Hope u can get this sorted m8 Wana know what causes this two
 
18's = extra unsprung weight and drag + a cabby is heavier than a hatch to start with. The best i used to get was 266miles to 9 gallon(i never let it go below 3 gallon) so 266/9=29.5 but my clocks read 17% out so 17% of 29.5=5.01 so my best mpg was 24.5. but i have got it as low 6/7 mpg really gunning it.
 
Well my 16v was getting 34 normal.running according to the trip, and around 140 miles to 30 quid. My l.4 only gets me an extra 20 miles on the same amount of fuel
 
First - try your brakes, if one wheel is wormer then another after few miles then they are foulty. Have you got map sensor on this engine? This could be a problem.
 
First - try your brakes, if one wheel is wormer then another after few miles then they are foulty. Have you got map sensor on this engine? This could be a problem.

I'll check them later but I don't think so, there is an awful smell of fuel from the exhaust though. Got a map sensor and swapped it over with another to if it made any difference but there was no change :roll:

Could it be an ECU fault? Would one of them USB to Renault cables help me out with a diagnosis? Would it show me a sensor being down possibly?
 
Could it be an ECU fault?

This hapening not very often. Make sure earth strap engine-body is in good condition. You might have a poor spark issue, in this case ecu will put more fuel to the engine trying to keep it working. So first to do is to make sure thet spark on all cylinders is good.
Another thing is engine temp sensor for ecu, if this does not work properly then ecu might use "choke" at all time.
 
This hapening not very often. Make sure earth strap engine-body is in good condition. You might have a poor spark issue, in this case ecu will put more fuel to the engine trying to keep it working. So first to do is to make sure thet spark on all cylinders is good.
Another thing is engine temp sensor for ecu, if this does not work properly then ecu might use "choke" at all time.

Cheers for that mate, I'm going to have a good look at it in the morning. I was working last night and really can't be bothered going under the bonnet tonight :roll:

Engine temp sensor is that the same as the Coolant temp sensor? If so I put a brand new one on just last month. I think I could have a poor earth now you mention it. Chris H said the same thing.

Just say the problem is a poor earth, if I take all my plugs out and check the spark and it's weak, will I notice an instant change in the spark if I get a better earth?

Thanks for the advice, I'll let you know how I get on (y)
 
i get 350 miles out of a tank in my cabriolet. When the clutch was gone it dropped to 300. I find the 1st quarter tank is 80 miles and the last is 100 miles, possibly due to the shape of the fuel tank or my foot getting lighter :lol:
 
Engine temp sensor is that the same as the Coolant temp sensor?
Yes, I dont know your engine but in mine I have one for ecu and another one for dashboard guage.

Just say the problem is a poor earth, if I take all my plugs out and check the spark and it's weak, will I notice an instant change in the spark if I get a better earth?

Thanks for the advice, I'll let you know how I get on (y)

At first I suggest to put jump leeds from minus on battery to the engine body then start the car, you schould feel the difference straight on.
 
Been out this morning and cleaned up all 3 earths, one on to of the gearbox into the loom, one from the rear of the head to the bulkhead and the other from the gearbox to the chassis. Made sure they were all cleaned back to bare metal and so were the points of contact on to the chassis.

haven't really noticed a massive difference to be honest yet

Just wondered if the injector on inlet manifold might have a fault and it's letting fuel pour in? What does this sensor actually do, add petrol on a cold start?

Also the knock sensor on the front of the head? What does it actually do?

can anyone tell me what colour the plugs are from the loom that plug onto both sensors (knock and cold start injector?) please?
 
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Update,

been out in my car after doing the work this morning and it seems alot better on fuel. I had pretty much no petrol in my car, the gauge was reading exactly on the bottom line and the petol light was not on. I drove for exactly 20 miles then the light came on, so I stopped for fuel and put in a tenner which should give me 45/50 miles if the problem has been fixed. The gauge is reading well above the bottom so judging how far I got on empty plus what the gauge now reads I should get 50 miles easy :)

I'll have to just wait and see.

Thanks for everyones help. (y)
 
Whats the power delivery like? maybe the cat is fucked?

Power seems ok, but I have a new cat on my list of things. I have no idea the condition of it but I know it is still intact because when I fitted my new exhaust a few months back it looked ok (imo :lol:).
 
The problem seems to be fixed now, done 35 miles and the petrol light hasn't come on or flickered once. This means I have got at least 35 so far to my tenner

35 miles per £10 x 7.7 (£77 to fill) = 269 miles per tank. Thats been urban driving and I am expecting another 10 at least which would be 45 x 7.7 = 346.5 miles per tank, 146.5 more than I have been getting.

Problem solved :)

thanks again (y)
 
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