LCR illogical MPG?

[6th.replicant]

Having a bit of head-scratch re my LCR’s touring mpg, wonder if you folks have any suggestions?

Bought the car – a ’03 210, 45k, 1 owner, fSsh, standard map – in June ’08.

At first, its touring/motorway mpg was 34-36 when cruising at a steady 85-90mph (ie 3250-3500rpm in 6th), which seems to be similar to other LCR owners on SCN.

Two months later, during a long trip, the touring mpg suddenly dropped to 29. Then, 2 hours later, one of the coils died – all 4 were replaced. However, still get 29mpg on long runs.

Yet, in town it does 23-27mpg (depending on light or heavy traffic) & 37-40mpg when cruising at 60mph.

I had a VAG-COM ‘road test’ done by AMD, which indicated that the MAF was faulty. New MAF was fitted, followed by another road test with VAG-COM & the readouts indicate that all is running AOK – but no change to mpg.

In addition to scheduled servicing, I’ve re-set the ECU (thrice); fitted a new air-filter (Green Cotton panel); new temp sensor; new fuel filter; new plugs (NGK plat’); and the engine oil is Millers XF fully syn’ – none of which have had any affect on the mpg.

Tyre pressures are always correct, as is the tracking/alignment (laser); also checked that the brakes are not binding.

Tried using Shell V-Power (4 consecutive fill-ups) – no change.

I’m pretty certain that it’s not my driving-style. As a yardstick, I do a regular trip from London to Brecon (M25, M4 + A/B-roads; 240-ish miles) that I’ve driven in various cars over the years & always achieved OK mpg, for example: 911 (996) Carrera 4S – 26mpg; ’04 Jag XJ 4.2 V8 – 27mpg; Honda S2000 – 32mpg; Mk5 VW GTI 2.0T – 37mpg. My LCR – 29mpg.

In all other respects, my LCR runs fine – no lumpy tick-over or surging, always starts 1st time etc, revs sweetly, feels mighty quick & doesn’t use any oil.

TBH, I'm not too concerned with the cost implications of the 5-7mpg drop. However, I am concerned that this anomaly is indicative of a fault ...

Any suggestions? Ta.

 

[Willie]

All the other cars above are NA apart from the MK5 GTI. Perhaps its down to your driving style.
The best fuel economy I have gotten in my standard map LCR was 42.5 MPG avaerage over a full take of fuel. This was gotten by very very slight feathering of the throttle.

Have you run VAG com logs to see whether you have a boost leak?

Have you checked your PCV set up to see it is still okay?

Have you checked or changed the lamda sensors?

Have you had a RR/logs done to see if your running very lean/rich?

Hope this helps

 

[6th.replicant]

Thanks for response & suggestions, Willie.

... Perhaps its down to your driving style...

Pretty certain it's not my driving-style, cos I get 23-27mpg in-town & 37-40mpg on a 60mph cruise. Plus, I was initially achieving 34-36mpg at steady 85-90mph & haven't changed driving style since.

Have you run VAG com logs to see whether you have a boost leak?

AMD did a run with VAG.com & reported that boost was fine, no leaks etc.

Have you checked your PCV set up to see it is still okay?

Sorry for being dumb, but what's 'PCV'?

Have you checked or changed the lamda sensors?

Not checked lamda sensors - does this require VAG.com or is there a 'manual' method?

Have you had a RR/logs done to see if your running very lean/rich?

No RR/logs, but have repeatedly checked the spark plugs' electrodes & they're always the 'correct shade of brown' - ie not black (rich) or pale grey (lean).

Thanks again.

 

[Willie]

The PCV system is part of the block venting that has been known to be a weak point all through the VAG range. This isn't usually linked to a change in MPG more a change in performance, but worth a check anyway.
This is below your intake manifold.
I'm not too sure about any checks for the lamda probes.

 

[6th.replicant]

The PCV system is part of the block venting that has been known to be a weak point all through the VAG range. This isn't usually linked to a change in MPG more a change in performance, but worth a check anyway...

...I'm not too sure about any checks for the lamda probes.

Again, thanks for response.

Will investigate PCV - do you know what PCV abbreviates?

Re lamda probes: been advised by my garage (a long-standing VAG specialist) that if the lamda sensor was faulty, then a) a light on the dash would illuminate & b) the car would not have passed its recent MOT. Correct?

Garage also suggested that cleaning the throttle body could be a solution?

Ta

 

[Ruddmeister]

So you are loosing around 5 mpg? the changes (new air-filter (Green Cotton panel); new temp sensor; new fuel filter; new plugs (NGK plat’); and the engine oil is Millers XF fully syn’ ) wouldn't affect it as far as I can see.

No fault codes.

Throttle body may be worth a clean as suggested

It could be slightly over fuelling, maybe try changing / swapping / cleaning the 3 bar FPR (fuel pressure regulator) I fitted a 4 bar FPR in error, I was massively over fuelling, getting 20mpg although apart from less power no other symptoms.

Slightly left of field cure, a phase 1 remap. Like many people I saw better economy after the remap.

This is the kind of issue to which there could be 100 explanations.......it could drive you mad finding the answer....

Sorry I can't be more specific with things to try......

 

[DPJ]

I'd really like to see some vag-com logs before commenting further.

 

[Ruddmeister]

I'd really like to see some vag-com logs before commenting further.

Logging with VAG COM to see if anything looks odd is a good place to start if he can get access to a copy

 

[6th.replicant]

I'd really like to see some vag-com logs before commenting further.

... if he can get access to a copy

Thanks for responses.

However, can't access VAG-com, or even DL the free/share version because laptop is a Mac (OS X).

Anyone in the south M25 area or north(ish) Kent have VAG-com, please!

 

[Healyrae]

This might sound like a daft question, but do you drive with the average or actual mpg showing on the dash comp?

I constantly drive with mine on the actual mpg setting and the difference you can get with the slightest touch on the throttle is unreal.

Drive with that on, and watch your actual mpg at all times, then when yuo get home check the average.

Im doing about 35mpg with a mix of motorway and A roads.

If I don't put the actual mpg on dash and just "drive normally", I then get 26mpg.

Works for me.

 

[6th.replicant]

This might sound like a daft question, but do you drive with the average or actual mpg showing on the dash comp?

I constantly drive with mine on the actual mpg setting and the difference you can get with the slightest touch on the throttle is unreal.

Drive with that on, and watch your actual mpg at all times, then when yuo get home check the average.

Im doing about 35mpg with a mix of motorway and A roads.

If I don't put the actual mpg on dash and just "drive normally", I then get 26mpg.

Works for me.

My mpg figures are based on manual calculations - ie fill-up, do journey, re-fill, then calculate distance/fuel used - & the trip computer's average mpg readout; surprisingly, the latter is actually 100% accurate.

 

[6th.replicant]

I'd really like to see some vag-com logs before commenting further.

Hi Dave

Found someone who's kindly offered to assist with VAG-COM logs.

Can you please advise re process for acquiring correct/relevant data? (I assume it's a case of plug-in 'n' drive for a specific distance & period at 85-90mph - if so, for how long & how far?)

Ta