OK. Slightly weird problem: We've had an Octavia 51 plate (ie late 2001) for a couple of years & it's been totally reliable (apart from the aircon compressor -- see related threads :( ) except for one fault: when the roads are very wet (ie, *lots* of road spray) the car is really down on power. It's absolutely fine the rest of the time & light rain doesn't affect anything.

As far as I can tell, the turbo is not kicking in at all when it's in this state - there's no turbo whine & the kick of acceleration from 2k up is simply not there (which is bit perturbing when you want to put your foot down in order to merge onto the motorway!)

So, any thoughts? The air filter was changed about 7k ago fwiw. Could the box round the air filter be leaking and lett ing the filter get soaked? Could the MAF be playing up in the wet somehow? Anyone else seen this?

Any suggestions gratefully received!

Phil

Probably not the same problem, but I had a similar occurrence in my turbo-diesel Astra last month after driving through flood waters (not quite the same as heavy rain). Turned out that I had destroyed the boost actuator valve - felt exactly like the turbo had gone. Possibly something similar, maybe the sensor controlling the valve is getting wet, or the valve is sticking in wet weather?

Probably not the same problem, but I had a similar occurrence in my turbo-diesel Astra last month after driving through flood waters (not quite the same as heavy rain). Turned out that I had destroyed the boost actuator valve - felt exactly like the turbo had gone. Possibly something similar, maybe the sensor controlling the valve is getting wet, or the valve is sticking in wet weather?

Hmm. Could be. Do I really want to do round spraying different components with water to see if they stop working though?

Phil

pharm - does the problem go away if you switch off the engine, wait a couple of seconds then re-start?

Sounds to me like its the turbo inlet hose in the offside front wheel arch. It has been revised to improve the seal at the top.

If it were on a diagnostic machine I'd bet you'd see a 17705 error code.

This may be of interest:

http://www.briskoda.net/forums/octavia/where-pipe/51329/

pharm - does the problem go away if you switch off the engine, wait a couple of seconds then re-start?

Haven't had a chance to try: will do next time. I've never really wanted to stop (it's always those long journeys in the rain when you just want to get home & get it over with...)

Sounds to me like its the turbo inlet hose in the offside front wheel arch. It has been revised to improve the seal at the top.

If it were on a diagnostic machine I'd bet you'd see a 17705 error code.

I stuck VAG-COM on it after the last time & there were no fault codes logged. Unfortunately the only laptop I have with a serial port died a horrible death a couple of weeks ago so until I can track down a replacement I can't check for any current fault codes.

My only quibble with this is: why only in the wet? I supose the water could be lubricating the hose joint enough to let it shift or something.

cheers, Phil

My only quibble with this is: why only in the wet? I supose the water could be lubricating the hose joint enough to let it shift or something.

Hmm. Now I'm trying to remember if there's been a time when it wasn't wet. There might have been one a year or so ago.

Annoying that it happens so rarely in a way. I'll try cycling the ignition next time.

cheers, Phil

IMHO it is well worth changing that hose for the new one (revised seals) anyway - if that is not the cause of the problem then you're bound to have issues with it later on.

what engine is it Pharm, the pipe that goochie refers to is only on the 1.8T, the 1.9TD is completely different. I'd say its not the pipe though as the pipe coming loose doesn't reattach itself, logs a fault code(17705 i think) and you can hear the turbo whistle quite loudly as all the pressure is escaping.

best of luck though.

If it is a TDI and you have not changed the MAF yet I would do so, also put in a new genuine or good quality air filter at the same time.

I know that water would cause the MAF to go funny over a period of time.

mine is acting a bit odd tonight at low speed, jumpy and not smooth, but mine is petrol and no turbo.

what engine is it Pharm, the pipe that goochie refers to is only on the 1.8T, the 1.9TD is completely different. I'd say its not the pipe though as the pipe coming loose doesn't reattach itself, logs a fault code(17705 i think) and you can hear the turbo whistle quite loudly as all the pressure is escaping.

best of luck though.

110 TDI.

I'm fairly sure there was no turbo whistle.

cheers, Phil

in vag-com log boost in the dry then again in the rain, also a few other things that you could log that might help

Disregard all I have said above - I assumed it was a 1.8T