1.2TDi enormous fuel consumption

If it's a leak as in fuel is pouring out on ground somewhere, then his DIS display would not show any change in consumption, as miles per gallon are calculated not by measuring fuel level in tank vs miles, but injector reported (calculated) injected fuel amount in cylinders.

PD injector seal leak is possible - if any of seals are bad, then injector wont work properly, ecu will compensate to some extent and car will still run.
 
Also worth checking coolant and fuel temp sensors are ok

Cheers Spike

Should have explained the coolant temp sensor is a dual channel unit with one feed to the gauge and the other to the ECU. It's possible the gauge can read correctly but the engine is seeing much lower temps. From cold the ECU delivers two or three time more fuel than when the engine is up to temperature which could explain the problem
Out of calibration sensors don't always flag up fault codes so it's useful to log them with VCDS,

I think the ECU also adjusts fuel delivery depending on fuel temps so this could also be logged

Cheers Spike

PS. Have you checked for high oil level to see if fuel is draining into the sump
 
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Look at what is coming out of the exhaust. White smoke and/or soot would indicate failed seals. The engine may also run unevenly.

There are two parts of the fuel circuit. Fuel is drawn from the tank by the fuel pump on the end of the camshaft; this part is under vacuum and is therefore less likely to leak. The second part is the return from the engine to the tank via the fuel cooler; this part is under pressure and more likely to have a leak. The leak on the pressure part may only show with the engine running.

Also check for binding brakes.

RAB
Engine runs smoothly, clear smoke coming out of exhaust pipe. Can't find any leaks, but will check again under car when there'll be available lift. Wheels are the same temperature as far as I can tell...

If you can scan another good 1.2 and save its data you can compare it to your own. Not convinced a scan is the complete answer as not every part reports its status back to the basic computer in the A2. What is the mileage sorry Km on the car, how good is the service history, again when was the fuel filter replaced, fuel temp sensor will affect economy but not by that much. Have you run the car with the engine cover / insulation removed.? All fuel hoses are bone dry and no leaks below tandem pump?
I checked injection amount and air mass and it seems very close between two cars. Filters were changed less than 10k km ago and car has 250k total. I have engine insulation on, there's a little oil under it, but not a lot. Can't smell any fuel tho. To check under engine I'll need to take off underside metal plate that acts as a guard, waiting for an available lift to do so.

Can anyone help me create a checklist of what to compare between cars and how to get there in vcds?
 
Can anyone help me create a checklist of what to compare between cars and how to get there in vcds?
I gave you some names. If you don't want the help, please say so. I don't think you understand the fundamental issue that of the ca. 7000 1,2s built, the vast majority stayed in Germany and so that's where the knowledge is concentrated. In fact, I can specify that; 4221 were registered in Germany in 2007, and that was down to 2511 in 2016.

- Bret
 
I gave you some names. If you don't want the help, please say so. I don't think you understand the fundamental issue that of the ca. 7000 1,2s built, the vast majority stayed in Germany and so that's where the knowledge is concentrated. In fact, I can specify that; 4221 were registered in Germany in 2007, and that was down to 2511 in 2016.

- Bret
Alright, I get it. Still, common TDi tests list was very helpful.


Hi WaIIK.

Do you use a genuine vcds cable? If yes. Checkout the TDI info at Ross-tech.

http://www.ross-tech.com/vag-com/cars/tdi.html
Not quite, but the program is the same. Thank you!
 
This doesn't seem like an issue that is specific to 1.2's. Changing gear when you don't expect it may indicate a disconnected hose connection between the turbo and the inlet manifold or a failed intercooler. Have you removed the bonnet and looked underneath? Not sure that that would be the only issue to cause high fuel consumption.

RAB
 
This doesn't seem like an issue that is specific to 1.2's. Changing gear when you don't expect it may indicate a disconnected hose connection between the turbo and the inlet manifold or a failed intercooler. Have you removed the bonnet and looked underneath? Not sure that that would be the only issue to cause high fuel consumption.

RAB
It seems solid, I even squeezed it a bit :)
I don't have radiator grille (was lost before me) so the radiator isn't in the best condition. I'll ask someone fluent in diesel engines to look at my intercooler, thanks!

On another note, momentary fuel consumption is really close to average on DIS when driving. I'll figure out how to make a graph with fuel consumption and injection amount on the same screen and will record it. Hopefully I'll be able to do the same with working (at least mileage wise) 1.2 and compare.
 
So.... what was the final verdict? Did you solve the fuel consumption issue?

So many interesting threads on here, with such a wealth of experience and generous input - many hours of conversations and investigations - then they just cut off dead! No conclusion, no resolution, no update. I don't really understand why - isn't it etiquette on here? Otherwise, very friendly forum.
 
So.... what was the final verdict? Did you solve the fuel consumption issue?

So many interesting threads on here, with such a wealth of experience and generous input - many hours of conversations and investigations - then they just cut off dead! No conclusion, no resolution, no update. I don't really understand why - isn't it etiquette on here? Otherwise, very friendly forum.
I'm sorry to leave you hanging.

No, it didn't go back to normal.
I've got orings and copper washers changed on injector thingies (not sure what the proper English name) and nothing changed. They said it would be good to change spray nozzles as a whole or just spraying part, but that's really expensive, so I've left it at that.
They also adjusted ignition delay, promising that it would liven up the car and slightly reduce fuel consumption, but it did just the opposite. I can't convince them that they are at fault here, as ignition is "less then a degree away from ideal" (they checked it with VagCom). I can't confirm nor deny it as I don't know where to look in VCDS.
After all this operation my start-stop doesn't start the car anymore (just clicks). Starting manually works ok. I've paid to service my starter too, turns on faster with key, but still not on eco after stopping ):

Now my turbochager acts up (can be a big part of my mpg), G38 gives implausible signal sometimes (left me almost stranded once) and steering angle sensor turns off abs and esp (adaptation helps for 100km or so).

So I've got a lot on my plate with this car. 6L/100km if driving calmly is acceptable for now.

I think I need to scratch together some cash and find 3L specialist to look at it. Local mechanics are just no knowledgeable enough or I haven't found the one.

Thank you all again! Sorry to disappoint.
 
Did you test injectors on a test stand (out of car)? Turbo could not spool fast enaugh if there is lack of exhaust gasses due to insufficient fueling... That was a problem on my A2. I did put existing injectors on test stand to confirm the problem and changed injectors afterwards with tested good used ones.
 
Did you test injectors on a test stand (out of car)? Turbo could not spool fast enaugh if there is lack of exhaust gasses due to insufficient fueling... That was a problem on my A2. I did put existing injectors on test stand to confirm the problem and changed injectors afterwards with tested good used ones.
Yes, they tested it on a big scary test stand. They said it was dispersing a little more fuel than needed (if I remember correctly), but not very far from normal operation.

New injectors cost nearly a grand (870 pounds is local dealer's quote) so just changing them is not an option really.

Turbo just turns off if you drive hard for a period of time, but will start working after turning off ignition. I'll take it to specialist in the near future, city driving is almost unaffected by that (apart from mileage of course).

My gearbox robot left me motionless on railway crossing. I did eventually drive away, but that were very scary moments sitting with open door playing with gear lever...

I got car towed and am waiting for clutch (should just change it if I remove gearbox) and cam belt (it is time for a replacement). I'll change that 8 euro sleeve, probably clutch slave cylinder and G38 sensor and will hope that were all my problems for now.
 
Hello. My car eat a lot of diesel. What was your problem ?
My turbo is not in the best shape.
Thx.
 
Hello. My car eat a lot of diesel. What was your problem ?
My turbo is not in the best shape.
Thx.
I fixed everything I mentioned in previous post except turbocharger. It's still around 6L/100km, so 90% chance it's ECU knowing about turbo problem and adding more fuel to compensate
 
after i fixed everthing, i have the same problem whit fuel...
if i gone make a chip tuning ...maibe the problem of the ECU it's gone disappear ?
 
I fix everything except injectors because in VCDS test they are in the limit.
 

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