Fuel Economy Question...

[Jim 2]

Inspired by a semi-related post on the eGroup earlier today, and by my 250 mile round trip to Huddersfield this weekend, I wanted to ask a few questions.

 

Firstly... is the fuel economy on (modified) Corrado G60's accurate? I ask because I managed to return a pretty astonishing 37.1MPG this weekend on my drive down the M1 - admittedly I was not giving the car any stick apart from the occasional squirt up to about 90-100MPH to get past some troublesome drivers, and was lumbering along at about 70-80MPH the rest of the time. And even then on the A-roads near my house I was doing about 60MPH so... is 37MPG accurate? Looking at the boost gauge I was rarely taxing the G-Lader so perhaps this is why? Its just funny because this is hugely better than my old 16v used to give me.

 

Secondly.. what kind of fuel economy do you guys get? I do get a pretty eye watering 20-22MPG going to work in the morning, but I suppose thats what you get if the car hasn't even warmed up on a morning!

[Henny 0]

yeah, on the long run to Cornwall last summer, I sat at a nice relaxed 70 -> 75 on the motorway and got a calculated 37mpg... the MFA was reading 36.5... 8)

 

It's start stop stuff that kills the economy on the G60, cruising on a motorway at a steady (70ish, not 90ish!) speed will give pleasantly nice economy... add 20->25 mph on and you'll see it plummet to around 28mpg :roll:

[Jim 2]

I noticed that quick bursts of speed produce entertaining drops in economy too.. if you reset the MFA and are getting like 45MPG and then toe it, it'll just shave 10MPG off instantly.. kinda funny ;)

 

But back to the topic.. i'll have to try a steady 70MPH next time. Problem is most of the time, the general traffic flow is around 80MPH and its harder to keep at your own speed rather than go with the flow.

[BeavisJem 0]

Ok now i have just got in from a drive from Norwich to London where i live 135miles and on the mfa i got no more than 24.4 mpg :cry: , i didn't exceed 75mph and it was clear all the way. Whats wrong with my car? I even reset the mfa in mode 1 and again it started at 66 then 30 then it evened off at 24 mpg after about 3-4 mins.

 

I have a standard 92 G60 with stage 4 charger and supersprint backbox. And i was using optimax. Only me in the car and no luggague.

 

Should i start to get worried.

 

Seems to drive ok.

 

BeavisJem

[Henny 0]

drop your speed to 65 -> 70 and you'll see a difference in the economy.. ;) Odds are that your speedo's out (under reading) of the MFA isn't as accurate as it could be... Fill 'er up, do a trip at 70, fill 'er back up and work out your economy by hand... My old 16V 'rado's MFA fuel economy gauge was loads out! :roll:

[jedi-knight83 0]

i managed 30 mpg on a 140 round trip to london yesterday...doing about 80-90 ish most of the way in my VR6.

 

MPG has gone up since i used Wynns hydrolic tapet cleaner about 3 weeks ago.

 

I also check the MPG with my own calculations when i got the car and it seemed pretty acurate...i should do it again some time and see if its the same still

[BeavisJem 0]

ok did my own calculating and i have worked out that i was getting about 22mpg on a run.

 

I did 178 miles on £28.76 of optimax at 78.9p a litre.

 

2876p / 78.9p per litre = 36.5 litres

 

36.5 litres / 4.5 to get gallons = 8.1gallons

 

178miles / 8.1 = 21.97

 

Included in this journey was 135 miles on the motorway and 50 miles on dual carridgeway to the coast 60mph all the way.

 

Hmmm i am starting to get worried. :(

 

Anyone got any ideas

 

BeavisJem

 

P.s did i work out the mpg properly

[jedi-knight83 0]

well first of all it will be more acurate to work out the mpg from a full tank? how do you know it was only 8.1 gallons

 

did you fill up , drive around, and fill up again to work out how much was used?

 

that sounds very low mpg for the type of driving. may be worth using some fuel injection cleaner and some of the tapet cleaner stuff i mentioned (do G60's have hydrolic tapets???)

[Henny 0]

Looks like you've worked it out OK... :|

 

Could be a lambda fault, making it run rich...

 

It's probably worth taking it to a garage and getting 'em to shove the exhaust gas analyser up the pipe to see what's coming out...

[Henny 0]

(do G60's have hydrolic tapets???)

 

yup, they have hydraulic tappets... 8)

[BeavisJem 0]

cool i think i will do that thanks, i just went and filled it up and i got 8.1 gallons in it.

 

and did 178 since the last fill up.

 

Cheers for your help guys.

 

What injector cleaner stuff should i use (should i use it) and if the lambada is messed up how much £££ are we looking at.

 

BeavisJem

[jedi-knight83 0]

i used some stuff that cant be bought on the shelf...it was from my mechanic friend, but redex would do a similar thing, and the tappet cleaner was Wynns hydrolic tappet / lifter fluid.

[Fat Tony 0]

Ok now i have just got in from a drive from Norwich to London where i live 135miles and on the mfa i got no more than 24.4 mpg :cry: , i didn't exceed 75mph and it was clear all the way. Whats wrong with my car? I even reset the mfa in mode 1 and again it started at 66 then 30 then it evened off at 24 mpg after about 3-4 mins.

 

I have a standard 92 G60 with stage 4 charger and supersprint backbox. And i was using optimax. Only me in the car and no luggague.

 

Should i start to get worried.

 

Seems to drive ok.

 

BeavisJem

 

I get the same on mine never see over 22mpg even when doing the reset at 56 mph it will go up slightly but not much. I done a 300 mile trip from Glasgow to Derby and filled up, worked out at over 30mpg on paper. I dont have much faith in the MFA mpg readings. You can look at the sns web site and you get the current reading i.e. not the average on one of the settings. Even when doing this my reading where poor. This points again to the fact that the MFA is way out.

 

Let me know how you get on when you get the car tested as I may have to follow. But 'm of the opinion that the MFA on my car (which is standard) is way out. I'll be mad as hell if my car has been running rich for 3 years (The thought of how much I have wasted on petrol would drive me nuts :mad: :mad: :mad: ) Can you tell from the MOT readings if the car is running rich?

 

Chhers

[Fat Tony 0]

"Notify me on" I keep losing posts that I'm intersted in Sorry :oops:

[Majik 0]

The bit that confuses me is that if you let the car coast in gear, foot off throttle the instant fuel economy is reported at 99.9mpg it seems like some sort of parameter for the switch, however if the car is stationery than the instant fuel economy reports 0.0 MPG. So i assume that as long as the throttle is pressed and the car is moving then the MFA will be accurate.

[jedi-knight83 0]

where do you get those read outs majik? i only get a average mpg, not instant???

[Jim 2]

There is a little MFA trick you can do which will report real time fuel consumption.. though I don't have the procedure to hand.

 

Isn't it the same procedure that lets you check the vacuum / boost pressure on G60's?

[Jim 2]

The bit that confuses me is that if you let the car coast in gear, foot off throttle the instant fuel economy is reported at 99.9mpg it seems like some sort of parameter for the switch, however if the car is stationery than the instant fuel economy reports 0.0 MPG. So i assume that as long as the throttle is pressed and the car is moving then the MFA will be accurate.

 

Well it seems to make sense...

 

If you are rolling forward using only the fuel required to make the engine tick over, then surely you would get enormous fuel economy. Especially if you coast at like 60MPH but the engine is idle.

 

But if you are not moving anywhere but are using fuel, then you are getting 0 miles per gallon as you are not actually going anywhere? :)

[Fat Tony 0]

Is there a fuel cut off switch on these motors?

[Supercharged 2]

My MFA is pretty accurate from what i've worked out, I have had 40mpg on a (slow) trip to Norwich last year (50mph all the way), I get 30mpg to work everyday which is a 12 mile journey with a mix of town and A road driving. G60's are pretty economic really. 8)

[Majik 0]

If you are rolling forward using only the fuel required to make the engine tick over, then surely you would get enormous fuel economy. Especially if you coast at like 60MPH but the engine is idle

the engine wont be at idle if you coast at 60mph on 5th gear it would be around 2500 revs but because the throttle butterfly is closed, the fuel must be enough to make the engine run lean, but cos the display has only --.- digits showing the maximum value it can display is 99.9 which could be inaccurate.

Doh! about the stading still economy! :oops:

[Jim 2]

Ah... well I meant if you dipped the clutch as well

 

But I do remeber reading something on a Bosch interactive CDROM about K-Jet fuel injection (spotted it on the desk of a lecturer in the motor vehicle dept at work and borrowed it to try and learn something) that when the car is on run-off (ie you aren't using the gas but the engine is still moving) then it doesn't use hardly any fuel... hence the astronomical MPG figure :)

[Henny 0]

yeah, on K-jet the air plate can be forced down as well when on over-run which just allows a trickle of fuel into the cylinders so that it doesn't just stall... Mega efficient for a mechanical system... 8)

[Guest]

ok, sort of relavent, had a weird thing this morning.

 

my MFA2 (total journey) read 25.4 MPG when I got in her this morning, this is over approximately 350 miles.

 

when I get to work I check my MFA1 (single journey) reading and it says 24.7MPG (15 mile journey) but the MFA2 now reads 25.5.

 

question is, if the journeys average fuel consumption was 24.7, how can the MFA2 average have increased to 25.5? I've thought about it, and can't work out a way that it has calculated this, any ideas? On the whole i'd say the MFA was very accurate though

 

I'm not concerned with the MPG readings here, as the the engine hardly warms up, and involves alot of traffic, and 120MPH blatt down a duel carriageway, best figures i've got was high 40s :D

[seanoVR 0]

managed to get 320miles out of a full tank of BP Ultimate. Does that sound about right?? Quite a bit of town driving was involved so am not sure if this is consistent with what you guys are getting. It's a VR6.