Warm engine consumption

[plavis]

Hi,
I recently changed timing belt and replaced vacuum pump with refurbished one (old one was leaking fuel in small ammount).

First thing I noticed that my brakes are stronger now.
Second thing is that fuel consumption is worse now, especially when engine is warm.
On idle, before intervention consumption was 0,5-0,6l/h, and now when engine is cold is the same, but when engine is warm it's around 0,9l/h-1,0l/h.
Also, on the road, my average consumption was before 5,0-5,5 l/100km, and now between 6,5-7,0l/100km

Do you have any idea?

 

[zslnk]

Sounds like a PD motor with vac pump leaking fuel. Tandem pump.

What was your torsion value pre/post timing belt replacement? Torsion is a number that relates to the difference between the crank and cam sensor. Adjusted with cam pulley bolts on the belt cog. If your consumption changes after a belt change, check the timing.

 

[plavis]

Torsion value is 2.2 on idle, and sometimes jumps to 2.8

 

[Tdijarhead]

Move the torsion toward .0 my fuel consumption at idle is about 0.4 , my last fill up two days ago got me 52.4 mpg. My torsion is set at -1.5.

 

[zslnk]

Agreed, I run my PD +/- 0.5 and I find it runs well, starts well and returns good mileage.

 

[plavis]

Interesting fact.
I monitored consumption by fueling to the top on several occasions. Actual consumption is more or less the same as before, but the display on the board computer is still quite high. Prior to these changes to the engine, the difference between the actual consumption and the consumption shown by the on-board computer was minimal.

 

[C.Powell]

On a 2003 ALH jetta wagon, using VCDS, I measure about 0.2l/hr fuel consumption at idle (c.900rpm) rising to between 0.3l/hr and 0.4l/hr with the air con running. I do not know if those figures are typical or not for fuel usage at idle. Engine warm or cold does not seem to cause a notable difference. Is the onboard computer giving an accurate reading?

 

[plavis]

Onboard computer was pretty accurate before changing timing belt and vaccum pump. Now onboard computer showing 30% worse.

Diesel consumption: 5,25 l/100km - Volkswagen, Bora, Bora

Volkswagen, Bora, Bora

www.spritmonitor.de

 

[Tdijarhead]

I think I misunderstood you. If you haven’t driven it and just had it idling then your fuel consumption will be worse on the screen. To get an accurate read on mileage a pen and paper is the most accurate.

I thought you were talking about fuel consumption in the measuring blocks with vcds hooked up.

 

[plavis]

Sorry for late response.
I set torsion value like it was before (0.5), but no change.
It must be related then with vacuum pump or something else.
Again, onboard computer was pretty accurate (2% error), but now it's showing poor mileage, and mileage itself (toping reservoir) is worse.

 

[BobnOH]

How many tanks have you measured? I would not trust the single readings, only full tank calculations.