Arl poor mpg after head new cam/head gasket

[M53494]

I've had a load of work done on my 2002 ARL engine recently.... New cam, bearings, head gasket, new piston rings, injectors overhauled etc etc.

The average MPG used to be 50.9 MPG over the previous 10,000 or so miles, but after the work it's down to 44.6 MPG over the 2000 or so miles I've done since. On a 'Miss Daisy' drive to work I'd easily get in the mid to high 60's MPG.....but now I'm lucky if I can get 49 MPG.

Having done some research, I've found that the crank angle can be adjusted (It should be around 0.0kw) which can affect the MPG. Having just had my mechanic check it on vagcom on tick over (903 rpm). Assuming that it's the "Synchro angle" is the reading I should be looking at in Group 004 - it fluctuates between -1.1KW... 0.0KW...and +0.6KW. There is also a reading for "Spec inj. duration" which is 5.6KW. These readings are within the parameters of what is indicated below each readings 'window'.

A couple of readings that DO appear outside their indicated parameters are in block 003.
The "MAF (actual)"reading is 445.9 mg/str but it allegedly should be between 210-370. Also "EGR duty cycle" reads 4.8% when it should be 40-70%..... HOWEVER, I've done the EGR delete! It's about 8 years since its had a new (Genuine BOSCH) MAF.

Group 013 shows
Cylinder 1 -0.59 mg/str
Cylinder 2 -1.11
Cylinder 3 -1.04
Cylinder 4 -0.61

I'd post pictures of the 11 pages of vagcom readings that I took, but can't (?) to this forum.

Can anyone offer any suggestions to improve my MPG?

Cheers, Kev :-) 👍

[zollaf]

when you say recently, how recent are we talking, and how are you getting the figures. new rings will need to bed in and will be tight until they do, costing power. are you relying on the dash display or have you done a tank brim to brim. new injectors can knock this figure out, as can the recent spell of colder weather, longer warm up periods etc..

[Crasher]

Firstly, how was the valve timing set and how were the injector stroke settings done?

[M53494]

The work was done in mid September and I've driven a good couple of thousand miles since. I've done one brim to brim tank MPG calculation which shows 48.02 MPG which is obviously better than what the computer is showing. However, that calculation was achieved by constantly driving like Miss Daisy. I do appreciate the cold weather will lower MPG but even bearing this in mind I just feel it should be better than it is....especially the run to work where I could achieve 67+ MPG that is now down to around 48 MPG! Although that's according to the trip computer, but it can't be THAT far out can it? I'm going to do a second brim to brim calculation next time I fill up.

The car does notably have more power/is more responsive than it was though! 👍

Regarding valve timing....I'm no mechanic and so didn't do the work, so I don't know....but can ask. What 'should' have been done/method used?
The injector stroke was set with the cam lobe at its highest spot, screwing the pin (That sits in the top of the injector) right down and then backing it off by 225 degrees. After the poor MPG came to light, these have been reset to 180 degrees, but with no seeming improvement.

Do the vagcom figures I've posted seem 'normal' or is anything untoward there?

Kev

[Eshrules]

I've had a load of work done on my 2002 ARL engine recently.... New cam, bearings, head gasket, new piston rings, injectors overhauled etc etc.

The average MPG used to be 50.9 MPG over the previous 10,000 or so miles, but after the work it's down to 44.6 MPG over the 2000 or so miles I've done since. On a 'Miss Daisy' drive to work I'd easily get in the mid to high 60's MPG.....but now I'm lucky if I can get 49 MPG.

I'll let Crasher help you out with the technobabble stuff, it's beyond me.

In regards to the MPG - notwithstanding the fact that you're using the inherently inaccurate DIS, to drop from 50 to ~45 in winter isn't all that bad - I can see drops of up to 15mpg depending on how cold the cold snap is but my commute is shorter than it once was and thus less time at running temp to help push the MPG up.

It's a difficult one when this crops up because many people assume the DIS to be correct but only really start looking at their MPG more closely following work, usually in the winter because it's dropped.

If you had brim>brim comparisons for the same time of year to work from it would be much easier to tell if there was a genuine issue.

[Crasher]

Do the vagcom figures I've posted seem 'normal' or is anything untoward there?

The figures for cylinder 2 and 3 aren't brilliant but are well within spec, personally I do not like to see them exceeds 0.50. The problem with these figures when they are out is what is the ECU reacting to? It could be ring sealing, valve flow, injector or their settings, poor quality inaccurately machined cam, all sorts.