220D Mpg / Performance With Full Tank (New Engine!)

bigmick777 · February 26, 2013

Hi Guys,

Ok, so I "appear" to be having an unsual issue with my car, I say appear as it's difficult to be 100% sure. Let me explain....

IS220D Sport, complete new engine fitted @ 92,500, they checked the EGR valve (OK) and acid cleaned the manifold etc as the engine etc as the old engine was extemely coked up.

So ran the engine in up to 100,000 miles and the new engine has been running really well (quiet, a lot more responsive, and the sport gearing is even better, car copes with 6th well under 50mph).

Tank AVG MPG has been about 37ish and has gradually risen since the engine was installed.

At 100,000 took it to the Lexus garage for MOT / 100K service, they also did the front pads and needed front tyres which I got from a local tyre place (Uniroyal)

Since the service / MOT the MPG had dropped to around 33 / 34. I noticed this from the moment I used the car - I travel 120 miles a day, same route, same speed etc (mainly motorway). I also felt that its down on power (car appears to be throttle back under acceleration it is marginal but I do notice something not right). I called Lexus on the first monday then during the latter part of the week the MPG started to rise and any concerns of performance issues disappeared!

It's now 3 weeks since service and it would appear to be when the car is full of diesel. It hovers around 34MPG tank average until tank half full then the average starts to rise to about 37 - 38! Similar story with my interpretation of perfomance issues, after half tank the car "seems" more responsive.

I certainly havent spotted this before and as doing a lot of miles I am sure it would have been obvious. Wouldnt have thought that there was any significant weight in the diesel tank. Checked tyre pressures (they were down so inflated to 42 front 45 rear iirc).

Sorry for the lengthy post but as this seems very unusual to me wanted to explain and welcome any ideas before I book back into Lexus.

Cheers, Mick.

bigmick777 · March 4, 2013

Thought I would post an update.

After another tank full I have now confirmed it has nothing to do with how much diesel is in the car - thought it was weird.

Anyway gave the car a reasonable blast over the weekend, filled up, put a havoline diesel treatment and travelled my usual Monday journey, no issues whatsover with power, felt really responsive, the AVG mpg (which hasnt been reset for the last 3 weeks) went up from 34.7 to 35.1 after just 60 miles and the TANK AVG up around 37 - 38.

Not sure the treatment has had time to do anything but starting to suspect that maybe the EGR valve

I tend to do 400 miles a week of steady driving (revs around 2K) and I had hoped with a new complete engine (modified parts) that the carbon wouldnt be as much of a problem but it sounds like my issue could be EGR valve related :-( not great as in 3 years of owning, I have had 3 EGR valves prior to the new engine.

bigmick777 · March 28, 2013

Well its still doing it!!

Really funny, the last tank I got 427 miles out of, previous was 480+ so MPG dropped from 38 to 32.5 without any real change in my driving style - I do the same journey each day.

Nipped it into Lexus to get them to check the codes as on hol tomorrow so driving cornwall. No codes reported (sort of expected as I aint seen any warning lights).

Scratching my head, may check the EGR valve see it it needs a clean - I have done approx 10K in the car since the new engine is in although it does go on long runs with revs > 2000K daily.

This may sound really daft but should the diesel filler tube have a little flap (about the size of a 10p)? I am sure mine used to but not anymore! There is a hole either side of the metail filler which looks like it could have had something fixed - could be a real long shot but if there should be one and this has come off the only place I can see it going is into the tank? Maybe interupting fuel feed into the engine?!?

Mick.

ronsis · April 20, 2013

filled mine earlier... my filler is the same as yours... hole plus two smaller ones either side ?

( just run from glasgow to london on cruise... 70mph...ish... all the way...6hrs 15 min. refilled with 36 litres... 397 miles = 51mpg ? ish ? i'm happy.)

Mouser · April 22, 2013

filled mine earlier... my filler is the same as yours... hole plus two smaller ones either side ?

( just run from glasgow to london on cruise... 70mph...ish... all the way...6hrs 15 min. refilled with 36 litres... 397 miles = 51mpg ? ish ? i'm happy.)

51 is much more like what I'd expect from the 220d, I get better mpg than BigMick from my 250, especially when doing mainly motorway travelling.

bigmick777 · April 22, 2013

filled mine earlier... my filler is the same as yours... hole plus two smaller ones either side ?

( just run from glasgow to london on cruise... 70mph...ish... all the way...6hrs 15 min. refilled with 36 litres... 397 miles = 51mpg ? ish ? i'm happy.)

Yeah thats the same filler as mine, it was a long shot! I think its down to some crap in the fuel system, DPF, EGR as after a good "swift" run to Newquay its been much better, no lag on performance.

I now get around 500 miles to a tank, 38 ish MPG but I reckon if I keep at 70ish it would do about 44-46MPG. To hit 50 I have to be doing 60mph, A roads etc - its could be less than yours due to the gearing on the sport.