Howdy folks. 

 

Cars sat on 68k, serviced every 5k miles since new.. last service was 200 miles ago. Around town it sits at 37mpg, on a long journey it can return 42-45mpg. This isnt trip, this is manual calculation.

 

Car has been scanned and returned no fault codes.  No smoke apart from a bit on start-up.

 

As far as mods go to the car, it is on 17" Ronal alloys. But I wouldn't of thought this would be the cause.

 

Possibly: MAF? Thought this would throw a fault code? Faulty injectors? Anyway to test this?

 

I know a lot can be down to drivint style, but i have tried a mix of driving styles over the past 10k miles and its never changed.

 

Any ideas?

 

Try cleaning up the maf with some contact cleaner first ??  just in case its caked in oil or the like. Thats all I can think of.  Do that first as it's a easy thing to look at.

 

How long has the fuel economy been low for? when did you notice it had dropped?

 

 

Dirty EGR valve, low tyre pressure, dirty fuel filter

Egr only cycle from cold tho? 

Binding brakes would be another one to check and cross off the list. 

 

JRJG 

I have covered about 14k since owning the vehicle.  When I purchased the trip indicated an average of 45mpg over the previous 2000 miles.

 

I will give the MAF a clean up for sure.

 

Tyre pressures are all fine, they are checked every Saturday.

 

Breaks are a possibility.

 

The EGR is deleted although I noticed that the lower intercooler pipe is caked in oil - so was planning to get all the pipes off and give them a clean as well as the intercooler.  Could this be a contributing factor?

 

As i say. Its never really bothered me the low mileage. But as weve done quite a few long journeys lately its just bugged me.

Seals leaking in an older turbo is quite normal. My old one was pouring and a few others I know of have oil leaks from turbo seals. . If it isnt whistling too much or smoking then dont worry too much.

 

Cant say for sure as my knowledge is limited but sure if that maf is picking up oily deposits then it could effect fuel...

 

See that Egr delete though..... That will effect fuel economy. And in a standard car it might drop it to those figures you are quoting.

Mine fuel economy dropped immediately after fitting my Egr delete on a standard car. Now its all tied in with the mods on my sig im returning 65-70 mpg on a long cruise. But before it was 48mpg with Egr delete.

It's the EGR delete, decreases economy, increases emissions, does nothing for performance. The most pointless mod you can do on a diesel car.

Mine used to average 47-ish on the trip meter. Would usually get 400 before the low fuel bong leaving an indicated 60-65 on board.

Used to get some huge numbers on certain summer trips. 60mph around the M25 at 25 degrees ambient netted a trip average of over 60, over 82 miles.

 

I kind of agree regarding the EGR. It smooths response on the overrun. If doing more rural driving, allowing engine braking to initially slow down for expected junctions is where a lot of extra economy comes in.

 

You could also play with your cam timing. but beware that it might strand you in colder weather. i.e. It might be fine until the first cold snap then not start.

http://www.autospeed.com/cms/article.html?&title=Big-Changes-from-Tiny-Adjustments&A=112521

 

J.

Edited 12 April, 20179 yr by vindaloo
tuning/timing meh!

Oh yeah....

 

Have a look under the back end at the rear calipers with the handbrake off. the handbrake arm on the calipers should hit a mechanical stop. Not "hover" in a mid-position. There are also cover boots over the cable ends. Make sure they're there and attached properly.

 

You can get helper springs to more reliably push the levers off. The real problem though is either a rusty/claggy cable or a problem with the main caliper piston/bore.

In the short term the springs are the cheapest way to try to get around the problem.

 

J.