Economy quick check

[Seanalf]

Hi all, we all know the fuel economy dips in winter, but I'm just looking to do a couple of checks to see if there's anything else potentially causing problems. currently, I'm struggling to get above 54mpg when this time last year, I was easily getting 60mpg. I've had new tyres (Bridgestone Potenza's with an A/B rating), tracking done and a recent service.

I'm going in for a gearbox service this week, just a touch overdue (5k) and I think that will help a bit, but I was wondering if I could plug in my icars to get some live data to just see if there's maybe an injector or even if the maf is out? I'm not picking up a drop in performance, no missfire that I can tell, so it may be something and nothing. Where could I find some guides/numbers on this or any pointers what to look for? I'm ok at the pulling bits apart, not so much on the plugging in bits

Most appreciated.

 

[Bobby Dazzler]

What’s the water/coolant temperature? Thermostats on the blink can affect fuel economy.

 

[markjay]

And make sure that your tyres are pumped-up to the higher pressure value within the permitted range ('loaded car').

Also, fill-up with premium fuel (Shell V-Power, BP Ultimate, etc), or alternatively pour some fuel additive (Redex, Millers, Forte, etc) into the fuel tank.

 

[KennyN]

Any sneaky wee dealer (emission) updates done when the vehicle was in for a service ?

K

 

[Seanalf]

What’s the water/coolant temperature? Thermostats on the blink can affect fuel economy.

Seems to be good, steady, no sudden drops, obviously takes forever to come up in the lower Temos at the moment, but nothing obvious.

 

[Seanalf]

Any sneaky wee dealer (emission) updates done when the vehicle was in for a service ?

K

Ahahaha

No, didn't use MB for the service, local specialist. It's only had the airbag done and the emissions was refused, that was over a year or so ago

 

[Seanalf]

And make sure that your tyres are pumped-up to the higher pressure value within the permitted range ('loaded car').

Also, fill-up with premium fuel (Shell V-Power, BP Ultimate, etc), or alternatively pour some fuel additive (Redex, Millers, Forte, etc) into the fuel tank.

Tyres done when I had them changed, used forte recently on a long run, she gets a good boot now and again as well, new dpf sensor just before winter, so initial basics done I hope. It's just odd it seems to have dropped off, hence why I'm looking for something else as to the reason.

 

[markjay]

Ahahaha

No, didn't use MB for the service, local specialist. It's only had the airbag done and the emissions was refused, that was over a year or so ago

Refused ant not done, or just refused...................?

 

[Seanalf]

Refused ant not done, or just refused...................?

Refused and not done

The car has been running fine with good economy until the last few months, at least 18mths after the airbag was done.

I've managed to get out and get some live readings. Engine cold I'm getting a MAF reading of 2.1lb/min which seems high to me? I'm going to run her up to hot and have another look, but I'm sure it should be lower, even cold.

 

[Seanalf]

Swapped out the MAF for one I had here as a spare (old one from a scrap car), plugged that in, dropped to 1.4lb/min cold, took it on a run, full temp, but of miced driving, came back to idle at approx 1.6/7 lb/min or around 12.8 g/s, does that sound about right? If so, I've found the fault, or at least improved it (I hope).

With a view to replacements, anything from £400 to £30, any recommendations to look at/avoid? I'm assuming Bosch are a good option?

 

[tonysmb]

In addition to what you've already picked up, any indications of a sticking caliper?

 

[Seanalf]

In addition to what you've already picked up, any indications of a sticking caliper?

No, no excess heat, new pads about 1k ago. Drove in this morning and with the spare MAF on, the economy is better.

Be good to have a comparison to see if it is similar, higher, massively out to others. Before I go taking a leap on a new one. I'll get some cleaner too, see if that helps, although it's not dirty in there by any form

 

[Seanalf]

I'm also wondering if I should clean the EGR? Not seeing any smoke etc, but she's done 79k now and I doubt it's ever been off. Maybe go simple with a clean of the MAF, EGR and check airbox etc? Worth a go?