Golf 118 TSI Engine Failures and Service Campaign 24S4

[nicandlance]

Shouldn't you be speaking to VW about this? I understand your concerns, but no one here is in the right position to give you any guarantees with this particular issue.

I wouldn't expect an honest answer from VW... would you?

[logger]

I am open minded to as to the cause by the way. I have a hunch related to emission controls, not fuel, but will not be able to check until I see how my car compares after any ECU "fix" via VCDS. Anyone know at what part of operating regime this engine is exposed to the greatest heat stress?

Eureka. I think I can now confirm my hunch to be the case. Noticed something with the 118 about 6 months that, coming from a background of operating gas turbines, really surprised me. I susequently logged and recorded it again back when the tsi eng fail thread was here, before it got sanitised and erased. I nearly mentioned it to the protagonists, but thought they would scoff at me if I mentioned it. Anyway post SC 24S4 it clearly no longer has this extreme characteristic. Just got to check it once again and will report back later.

Suffice to say it is nothing to do with fuel types and all to do with aggressive emissions control.

BTW I ran some good long 20 minute drive logs with SC 24S4 last night and I cannot see any obvious changes in the parameters. This might be because I am missing something, but I think it is more because SC 24S4 changes nothing there.

[DracZ]

I wouldn't expect an honest answer from VW... would you?

And getting a false sense of security via someone who has no authority on the subject would be useful how?

[prise]

Anyone know at what part of operating regime this engine is exposed to the greatest heat stress?

Logger,

In response to your question, the worst heat stress is normally at WOT and max RPM (maximum gas flow). Most manufacturers tip in extra fuel at this condition to protect exhaust valves, cataytic converters, etc. You might be interested in the following quotes from VW's self study programme material for the dual charger engine:

"Up to now in petrol engines, the mixture was enriched
early due to the high exhaust gas temperatures.
The exhaust manifold on the 1.4l TSI engine is
designed for exhaust gas temperatures up to
1,050 °C. As a result, the engine can be run with a
high boost pressure and with Lambda 1 in almost all
map ranges."

and

"Due to the higher exhaust gas temperatures, the
outlet valves are filled with sodium for better heat
transfer. This reduces the temperature at the outlet
valves by approx. 100°C."

[parso_rex]

I'll bet that they don't run at Lambda 1 across all ranges now

[Flighter]

I even had a car that should have been recalled and wasn't. Grrrr!

[POLARBEAR666]

I'll bet that they don't run at Lambda 1 across all ranges now

I would bet money that this is the issue. Normally turbo cars since their inception have pumped out black smoke under full throtle to varying degrees as a result of moving from a lean cruise ratio (lambda 1) to a much richer full boost ratio.

This is because the extra fuel cools the pistons and engine in addition to accounting for the higher amount of compressed air at higher boost.

So, running lambda 1 at all ratio's seems crazy dangerous to me as you are never allowing the fuel to cool the turbo engine as almost all other turbo cars do.

You will also note that the GT and GT SPORT earlier cars do not have this failure issue and they use more fuel than the 118TSI.

[nicandlance]

And getting a false sense of security via someone who has no authority on the subject would be useful how?

Whatever...

I wasn't after a false sense of security... just hoping that someone 'in the know' might have some knowledge about why this issue was occurring and whether or not this recall is likely to fix it. VW are only likely to give you the 'spin'.......

[DracZ]

Whatever...

I wasn't after a false sense of security... just hoping that someone 'in the know' might have some knowledge about why this issue was occurring and whether or not this recall is likely to fix it. VW are only likely to give you the 'spin'.......

Unless you've neglected to read the past 12 pages of this thread, its all down to speculation at this point. The only one truly "in the know" would be VW themselves. As for your obvious mistrust for the manufacturer - I struggle to understand why an anonymous individual on an internet forum deserves any more? Although there's clearly an issue here, VW have both acknowledged and addressed it in a reasonable amount of time. We'll just have to wait and see if the update has the desired effect. So lets just get back OT shall we?

[prise]

I would bet money that this is the issue.

Who knows! - remember that in the original carsguide article, Karl Gehling from VWA was quoted as a saying that the change would reset the settings on the engine's knock-sensor. My last car (6MPS) had the opposite problem and until the software was upgraded would occasionally go into a reduced power mode becasue the knock sensor calibration was too sensitive.

The official cycle for the urban and extra urban tests used to measure economy and emissions are very sedate in terms of acceleration profiles (you could comfortably follow them in a fully loaded van) so I would be surprised if there was a need to compromise thermal margins to get improvements in the offcial economy figures. Also the words in the self study material were "..almost all map ranges..." which indicates that there are still regions where enrichment is required.

Your comment on the earlier GT is a valid one, however it is interesting that are no reports so far of this problem occurring in the UK and Europe on the current generation of TSI engines. I am not aware of any reports of pistons with holes in them, dropped valves or blown turbos which are the normal casualties of running too lean although running leaner does increase the tendency to knock or 'ping'.

The mazda DISI motors, particularly in the more heavily worked CX7 application were known for blowing oil seals on turbos due to heat soak so I was pleased to see that VW have a dedicated coolant pump that continues to pump coolant through the turbo after the engine is switched off and there are relatively few reports of turbo problems with VAG vehicles. I guess it also helps that most of the time the turbo isn't being asked to work as most driving around town and on the highway would be under 2500 RPM with the supercharger doing the work.