Alfa Romeo Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
748 Posts
Discussion Starter #1
Right - been keeping an eye on my miles per gallon since getting my 2.4 JTD Sportwagon ( 2001 ), 140 BHP engine. And I'm NOT happy:rant: I've read up on this site - and have done the following.

New MAF

New Airfilter

Working and clean EGR valve - currently blocked off.

The ONLY time I get ANY smoke is if I'm really hammering it out in first gear.

I don't drive like an OAP - but I'm certainly no boy racer.

I live in London, so most of my journeys are short town trips.

AutoLusso gave it the once over on their Saturday workshops, including diagnostics, and nothing was out of order.

Am using injector cleaner ( only just started so waiting to see if it helps )

The car is running very well, with no problems to report - other then low MPG

THESE ARE THE RESULTS I'M GETTING:

1) 80 MILES (motorway) --- 29.8 mpg

2) 136 MILES (motorway) --- 33.1

3) 96 MILES (motorway) --- 34.9

4) 110 MILES (motorway& town) --- 35.7 --best

5) 100 MILES (short town) --- 26.7

1) 46 MILES (short town) --- 21 -- worst

These figures seem very low to me:(

What I'd expect and be happy with would be 40mpg plus on longer journeys, and 30mpg plus on town trips.

Now the one thing I've yet to do is change the thermostat, which definitely needs changing as it's running cool.

So my questions are:

What difference ( in MPG ) will changing the thermostat realistically achieve?

And what else should I check that may be causing this?

Driving me nuts!!:rant: :rant:

cheers all.
 

·
Registered
Joined
·
4,772 Posts
I don't think 40mpg is an unrealistic figure on a run, so the figures do seem low, how have you calculated these?

How long have you had the car; have you had diesels before? Driving diesels needs a more measured use of the throttle and use of torque rather than revs. Anticipation of traffic conditions, maintaining correct (or slightly higher tyre pressures) and using fully synthetic oil all make a difference.

I changed my thermostat and to be honest it didn't make any significant difference, perhaps 2-3%, the big difference was warming-up time.

Hope that helps, if it doesn't improve a re-map may help or sell it and get a v6:thumbs:

Rob
 

·
Registered
Joined
·
1,786 Posts
My Croma (reported elsewhere) gets water temp up in 3 miles, previous Fiat diesels take 6-8 miles, wasting huge amounts of fuel. So short trips are expensive. You can only check mpg from fill up to fill up, on board computers can be anything from accurate to 10% either way. Unfortunately the Croma (2.4 auto, heavy car) is accurate, and is just below 37 mpg, with no heavy traffic use. I expected 45.
Engine temp is important.
 

·
Registered
Joined
·
1,038 Posts
Are you using a trip computer or calculating the MPG using (the only reliable method) the actual amount of fuel used for a given mileage?
 

·
Registered
Joined
·
377 Posts
When I first got my 136 I was averaging 29mpg, it then dropped to almost single figures when the boost pipe split. Once fixed I was got 36mpg on a 600 miles run (although I was fairly shifting) and this was with a standard Angel Remap. With a High map my MPG has dropped right down to the mid-20's I imagine but it doesn't help that I have a lead foot and only do relatively short journeys these days.
 
A

·
Guest
Joined
·
0 Posts
Having seen all you have done I think there are two explainations of your questions.

1) Yes you need a new thermostat. You need that engine up to operating temp ASAP for good thermal efficiency. Getting up to temp in 3-6 miles is pretty good I'd have thought, unles you are in traffic when it should be a lot quicker of course.

2) Short journeys are very bad news for MPG and affect diesels just as much as petrols, if not more relatively. You will quite simply not get very good MPG round town as you get too much short burst overfuelling, and too much stationary idling in queues and at traffic lights. A diesel is at its best at constant revs on a long journey just slogging along at an easy cruising speed with minimum starting stopping/accelerating braking cycles. Thats when you will see good MPG.

We get consistently high 40s on the long weekly commute ours does.

AlfaLincs
 

·
Registered
Joined
·
1,613 Posts
I never really got much more thn 35mpg in mine.

Driving style has a huge amount to do with it, one mans idea of a spirited drive is quite different to another - one may be like your gran whilst the other like they just stole it.

5 pots aren't massively economical in any car, volvo never got the economy from their 5pot petrols, and the d5 had to be driven at 50mph to get 50mpg!
 

·
Registered
Joined
·
563 Posts
Are you using the computer on the car for the mpg or by filling up the tank and seeing how many miles you get?! I normally get around 600 miles or so from a tank which normally indicates low to mid 50's on the computer, so they don't quite tie in(110 miles a day commute). Some times I've had an average of 67mpg on the computer, others it's mid 40's.

I'd get a new thermostat if you're showing much below 85 degrees when warm and check your tyre pressures are correct too.

Cheers,

Mark
 

·
Registered
Joined
·
12,881 Posts
Still got my stat waiting here if you want it ... :) ... I get 45mpg on mine but I mainly do motorway driving, if you are using the trip 'puter then that is always out, mine reports that I'm doing 53mpg!!!!
 

·
Registered
Joined
·
748 Posts
Discussion Starter #11
I'm measuring the MPG mechanically - I.E. fill the tank to the brim and calculate from the miles travelled and quantity of fuel used......
 

·
Registered
Joined
·
12,881 Posts
Time to get that stat sorted then ... you'll probably save the price of it in diesel alone ... (have you checked your tyre pressures as suggested by Mark?)
 
1 - 12 of 12 Posts
Top