VW sudden power loss issues

[VEEEUU]

Has anyone experienced the power loss issues as reported in the media recently?

It seems overheating in some engines can activate the "limp home" mode. If my 6r Polo had a temperature guage, then I would have half a chance in preventing such scenario.

VEEEUU

[nomadx38]

No - overheating will not put the car into limp mode (which shows engine and EPC lights)

What overheating will do is limit power output (by either shifting up gears or cutting fuel) to keep the engine running. This feels different to limp mode which has no power or throttle response. If the car is overheating it will let you know by the red temp light under the tachometer.

What you would have to do to get the temperature up that high I have no idea. Mine is always fixed at 90 degrees C regardless of 0 or 50 temps outside

[noone]

There were a lot of new threads in the last few days on those articles. The articles glossed over a few issues, sort of amalgamating them into one piece.

Are you hitting limp mode? If your car was overheating, what would you do? Drive with less acceleration? Modern cars should be designed to drive hard all day and not explode.

[VEEEUU]

Thank you for a very informative reply. Just a couple of questions if I may.

What relative temperature does an engine need to attain for the red warning light to come on. Does "red" mean it's got so hot it's too late?

It seems you have a temperature guage in your VW? No such luxury in a 6r Polo 1.2 TSI.

Also, the temperature guage in may previous Series IV Golf sat on exactly "12 o'clock" for 7 years. Like your car this was regardless of outside ambient temperatures. That is untill the water pump impellor started disintegrating. I was able to nurse the car to a VW workshop by watching the guage and pulling over when it indicated about 20% above normal. No such luxury without a temperature guage.

Kind regards
VEEEUU

[Rubbadub]

I seem to remember reading somewhere that the water temperature gauge (and this was for cars in general, not necessarily a VW) will say 90 degrees even when the real temperature is a few degrees either way of 90, so people won't panic when the temperature fluctuates a little. This is why the temperature seems to go up so quickly when the car is genuinely over-heating.

[Barracuda]

The oil temperature gauge isn't much of a necessity these days. Like what nomadx38 said, you'd have to be thrashing the car and for a pretty long time to get the 77TSI to overheat. If the car was getting into a high temperature range, a message would appear on the MFD warning you. Again, overheating really isn't a concern on the 77TSI's. I had a 118TSI golf as a loan one day... I swear, five minutes of driving it from a cold start and the engine was hot enough to fry an egg. I drove for ten minutes and when I turned the car off, it kept its radiator fan on for about 1 minute to further cool the engine. Those things have a serious overheating issue. Don't stress about overheating and the 77TSI.

[alexaescht]

VW sudden power loss issues

The TDI runs fairly cool as well, except when it's cleaning its DPF. The exhaust tip becomes hot enough to boil water on it (not actually joking) and the DPF itself glows red. I'm amazed that the foam on the engine cover hasn't melted yet – it sits right above the turbo and DPF.

[Barracuda]

The TDI runs fairly cool as well, except when it's cleaning its DPF. The exhaust tip becomes hot enough to boil water on it (not actually joking) and the DPF itself glows red. I'm amazed that the foam on the engine cover hasn't melted yet – it sits right above the turbo and DPF.

Wow! How often does it clean the DPF? Does it affect the engine performance at all?

[alexaescht]

VW sudden power loss issues

Wow! How often does it clean the DPF? Does it affect the engine performance at all?

Depends on how you drive it, but I'd say roughly every 1,500 to 2,000 kms.

Engine performance – you can definitely notice. Turbo boost is increased to counteract the leaner mixture used during the cleaning process which results in a hell of a lot of turbo lag. Engine noise increases dramatically and overall the car runs like crap.
Sometimes the ECU starts the cleaning process when the engine is cold which results in stalling, erratic idling and unburnt diesel coming out the exhaust because the engine's not up to operating temp and there's not enough fuel being fed into it, which can be interesting because coming up to intersections it either will stall or you have to rev the engine in neutral while braking. Once the engine is up to temperature it tends not to stall.

[wai]

What relative temperature does an engine need to attain for the red warning light to come on. Does "red" mean it's got so hot it's too late?

In days gone by, when cars did not have fuel or temperature gauges, these lights were known as "idiot lights". I am not sure the term "idiot" was aimed at the designers or the owners. In all probability it was the designers for being so stupid as to not providing a simple gauge.

Basically, when the light comes on, the engine has overheated. If there was a gauge, it would be in the red zone. The gauge would tell you how far into the red zone, and if it was continuing to climb.

If you are driving and the light comes on, pull over, stop where safe, and check under the hood.

By the way, the temperature gauge and simple warning light are of no use unless they can sense heat. If something like a coolant hose comes off, you may not get an indication of high temperature.

A friend of mine bought a MY11 Subaru Forester, and it does not have a temperature gauge. It has a coloured LED that changes from blue through orange and finally red. Not much use to him as he is red/green colour blind. To him, it is all the same brownish (his description) smudge.

[kaanage]

Depends on how you drive it, but I'd say roughly every 1,500 to 2,000 kms.

Engine performance – you can definitely notice. Turbo boost is increased to counteract the leaner mixture used during the cleaning process which results in a hell of a lot of turbo lag. Engine noise increases dramatically and overall the car runs like crap.
Sometimes the ECU starts the cleaning process when the engine is cold which results in stalling, erratic idling and unburnt diesel coming out the exhaust because the engine's not up to operating temp and there's not enough fuel being fed into it, which can be interesting because coming up to intersections it either will stall or you have to rev the engine in neutral while braking. Once the engine is up to temperature it tends not to stall.

Actually, it is pretty much the opposite process - EXTRA fuels is injected during the regen, during the exhaust stroke where it ignites so that there is extra heat for the regeneration process. This creates additional backpressure in the exhaust stroke so the car runs like crap (and uses extra fuel pushing up consumption).

Lean diesel operation will generate less power but cooler engine/exhaust temps.

[alexaescht]

VW sudden power loss issues

Actually, it is pretty much the opposite process - EXTRA fuels is injected during the regen, during the exhaust stroke where it ignites so that there is extra heat for the regeneration process. This creates additional backpressure in the exhaust stroke so the car runs like crap (and uses extra fuel pushing up consumption).

Lean diesel operation will generate less power but cooler engine/exhaust temps.

But isn't less fuel injected into the combustion chamber during combustion and then extra fuel is injected during the exhaust stroke? I read somewhere that a leaner mixture in a diesel increases NOx levels which increases temperatures helping to burn off all the soot.
I could be totally wrong but that's what I thought. Also (and I know these aren't always accurate) but the instant fuel consumption gauge normally sits at 0.4 litres per hour (at idle) and decreases to 0.2 and sometimes 0.1 litres per hour during a regeneration cycle.

[ill0gitech]

Has anyone experienced the power loss issues as reported in the media recently?

All electric power? No.

Lost power to the wheels? Yes, but not on a highway or at speed, but still dangerous. I've lost the ability to accelerate more than once whilst already moving slowly - specifically when changing lanes and turning corners.

[Guest001]

In days gone by, when cars did not have fuel or temperature gauges, these lights were known as "idiot lights". I am not sure the term "idiot" was aimed at the designers or the owners. In all probability it was the designers for being so stupid as to not providing a simple gauge.

Basically, when the light comes on, the engine has overheated. If there was a gauge, it would be in the red zone. The gauge would tell you how far into the red zone, and if it was continuing to climb.

If you are driving and the light comes on, pull over, stop where safe, and check under the hood.

By the way, the temperature gauge and simple warning light are of no use unless they can sense heat. If something like a coolant hose comes off, you may not get an indication of high temperature.

A friend of mine bought a MY11 Subaru Forester, and it does not have a temperature gauge. It has a coloured LED that changes from blue through orange and finally red. Not much use to him as he is red/green colour blind. To him, it is all the same brownish (his description) smudge.

Another example of not so good gauges are Toyotas which on some models dont register if the water drops out.

On my Landcruiser it would stay on normal until it got REALLY hot and then would move.
If however a hose blew and the water all went bye bye the gauge wouldnt move at all as it only worked when immersed in the coolant.

I put a sensor in the top hose to tell me if the water level dropped more than an inch

[wai]

But isn't less fuel injected into the combustion chamber during combustion and then extra fuel is injected during the exhaust stroke? I read somewhere that a leaner mixture in a diesel increases NOx levels which increases temperatures helping to burn off all the soot.

My understanding is that during regeneration, additional injector pulses are used when the exhaust valve opens to get a flame into the exhaust and take care of the soot, hence the additional fuel consumption.