Golf 118 TSI Engine Failures and Service Campaign 24S4

[cameronp]

That's way better than I've ever got from mine in similar conditions - your drive to work sounds similar to most of my non-commute driving. Currently has 4500km on the clock so it should be well and truly run in, have only ever used 98 RON from Caltex or BP. It's interesting that you were using 95 RON and getting better economy than I was with 98. I was actually thinking that the Golf was pretty damned economical because it was using up so much less fuel than my previous car - and about the same as my old Nissan Pulsar which was nowhere near as powerful.

I've only ever seen the average trip fuel meter drop below 7L/100km when travelling at low speeds (below 110, say) for long distances between stops. e.g. the freeway from Perth to Bunbury I got (IIRC) 6.7 L/100km, which is the flattest boringest 200km you could imagine, about half at 100 km/h and half at 110 km/h.

[prise]

Gee Stelex
Can't help wondering, if 'lean burn' feature of motor distorted due to incorrect information from Lambda probes!

I'm fairly sure that the 118 TSI doesn't use lean burn for a few reasons:

1) It would require NOX storage catalyst which isn't fitted (NOX storage catalysts can't be used in Aus anyway due to the sulphur levels in our fuel).
2) The data I and others such as LOGGER have obtained via the diagnostics port shows no evidence of lean burn. It runs at lambda=1 virtually the whole time, dropping a bit lower on full throttle and high revs (a lambda value of 1 equates to a fuel mix where there is just enough oxygen to burn the fuel completely. A value less than 1 is richer and a value greater than 1 is leaner).
3) The VW self learning material for the engine makes no mention of it using lean burn and says it uses "homgenous mode ( lambda 1)"

Most manufacturers using direct injection have stuck to homogenous charge (uniform mixture in the cylinder) with lambda = 1 as the cost of the catalytic converter required to clean up the nitrous oxides (NOX) produced during lean burn is prohibitive and ultra low fuel sulphur levels (<5ppm) are required to stop the sulphur poisoning the catalyst. BMW is one notable exception, however the models using this technology cannot be imported into australia.

[Corey_R]

I've only ever seen the average trip fuel meter drop below 7L/100km when travelling at low speeds (below 110, say) for long distances between stops. e.g. the freeway from Perth to Bunbury I got (IIRC) 6.7 L/100km, which is the flattest boringest 200km you could imagine, about half at 100 km/h and half at 110 km/h.

Holy crap man... I can get my POLO GTI with APR Stage I ECU, which VW rates at 7.9 in stock form, to do average trips below 7L/100km easily. I mean, this is a 14 year old 1.8T Audi motor. And we're not talking on highways either. Along Old Windsor Rd from Bella Vista to James Ruse to M4 to Parramatta Rd to Stanmore - I often get ~6.5L/100km. From Bella Vista, same route but off onto Silverwater Rd and all the way down the #6 through to Sutherland Shire, 5.9L/100km. These roads are mostly 70 and 80kph zones with lots of traffic lights along the way.

I guess it just comes down to how you drive your car, and also, traffic and how many lights you get

[prise]

I've only ever seen the average trip fuel meter drop below 7L/100km when travelling at low speeds (below 110, say) for long distances between stops. e.g. the freeway from Perth to Bunbury I got (IIRC) 6.7 L/100km, which is the flattest boringest 200km you could imagine, about half at 100 km/h and half at 110 km/h.

The tyres that come with the sportpack might give you a bit more rolling resistance but 6.7 seems high for that sort of run. Did you have had a strong headwind or crosswind becasue that can make a surprisingly large difference? In still air conditions my 118 TSI would normally use about 5.5 on a similar run. I've averaged 6.4 l/100m in the nearly 7000km since I bought it and I've got a combination of rubbish traffic and some freeway running.

[Cossor]

Thanks "Prise" for correcting my wrong assumption re VW using lean burn.
(Learn a bit more each day)
What I really had in mind, is if Lamda probe develops fault (Due to poor fuel)
Could this cause motor to enter unsafe operating conditions? Or would it just result in poor fuel economy?

[cameronp]

The tyres that come with the sportpack might give you a bit more rolling resistance but 6.7 seems high for that sort of run. Did you have had a strong headwind or crosswind becasue that can make a surprisingly large difference? In still air conditions my 118 TSI would normally use about 5.5 on a similar run. I've averaged 6.4 l/100m in the nearly 7000km since I bought it and I've got a combination of rubbish traffic and some freeway running.

It was pretty much still. My average over 4500km is around 8 L/100km, from a combination of a variety of different driving conditions. Even on a mostly-freeway non-hooning run I usually see a bit above 7 L/100. When I was waiting for my Golf to arrive and borrowing other people's cars on weekends, I was getting a bit over 7 L/100km on my dad's 2L Ford Focus and a bit below 5 L/100km on a friend's Golf TDI. All this is making me think there might be something odd about my car. I'll check the tyre pressures and oil level tomorrow (since I haven't looked at either in the time I've owned it).

Anything else worth checking out or experimenting with? I'm not sure that taking it to the dealer and saying "my fuel consumption is a bit higher than expected" would be particularly well-received. :-/

[prise]

What I really had in mind, is if Lamda probe develops fault (Due to poor fuel)
Could this cause motor to enter unsafe operating conditions? Or would it just result in poor fuel economy?

There are two lamda probes, one before and one after the catalyst so normally a fault in a probe would be detectable by the ECU as it would result in inconsistent readings between the two followed by the dreaded check engine light and limp home mode (poor power and economy) to prevent engine damage. If fuel was bad enough to damage the probe it would normally also damage the catalyst and as far as I know there haven't been reports of catalysts being replaced.

VW stated in their original response to caradvice that the ECU software changes were in relation to the knock sensor so it is more likely that some combination of knock sensor and fuel burn properties caused knocking to be undetected until it had caused damage. This would be consistent with the sudden nature of the failures. With high boost engines you only need a few seconds of knocking to permanently damage the pistons so a knock sensor calibration problem can be terminal.

The ECU via the knock sensor is actually listening for high frequency vibration at very specific frequencies. The knock sensor is bolted directly to the engine block at the back of the engine. The ECU software has to be tuned to the characteristics of that model of engine and sensor.

My last car was a Mazda 6MPS and it required an ECU update to fix the knock sensor calibration. In the case of Mazda the sensor had been tuned to be too sensitive so on two occasions without warning my car went into a limp home mode with no power and had to be restarted each time to reset it.

[prise]

Anything else worth checking out or experimenting with? I'm not sure that taking it to the dealer and saying "my fuel consumption is a bit higher than expected" would be particularly well-received. :-/

I'd start keeping records for a few highway runs on cruise control, making sure you have the tire pressures set correctly (get yourself a decent tyre pressure gauge and make sure you set the pressures before you drive when the car is cold). I'd record the following info.

Distance travelled
Average speed on the MFD
Average fuel consumption on the MFD
Fuel consumption based on old fashioned (fuel in vs k's travelled) if you get the chance - this will tell you over a few tanks whether the MFD estimate is out.
Weather (temperature, wind, rain)
How many passengers
Diference in height between the start and finish of the route - a 200m altitude change over a route can make a surprising difference. If you are doing out and back routes then this wouldn't matter.
Number of cold engine starts in the route.

That's about all I can think of, unless you're driving with the windows down or or something unusual like that.

[Cossor]

There are two lamda probes, one before and one after the catalyst so normally a fault in a probe would be detectable by the ECU as it would result in inconsistent readings between the two followed by the dreaded check engine light and limp home mode (poor power and economy) to prevent engine damage. If fuel was bad enough to damage the probe it would normally also damage the catalyst and as far as I know there haven't been reports of catalysts being replaced.

Many thanks 'prise'
This DOES put my mind at rest
(The previous reported Lambda probe problems and fuel sensitivity was I believe for Golf mk V)
Have been told by dealer my Golf will be MY11, so assume will have any corrections made by VW

[cameronp]

Average fuel consumption on the MFD
Fuel consumption based on old fashioned (fuel in vs k's travelled) if you get the chance - this will tell you over a few tanks whether the MFD estimate is out.

I've done this comparison already since I was in the habit of tracking fuel consumption (obsessive-compulsively?) back when I owned cars without trip computers. The MFD display has been pretty much spot on with the old-fashioned measurement.

That's about all I can think of, unless you're driving with the windows down or or something unusual like that.

Nope, nothing unusual that I can think of...

I'll be making a trip to Joondalup on the weekend (about 30km+ of freeway each way), so I'll start keeping some records when I do that. And if I post any further on this I'll make a separate thread to avoid incurring the wrath of the moderators, since this is wandering a little off-topic.