Sudden Drop in RPM during heavy rain.

[Klevo]

Hi Guys,

I own a vw polo 6n1 1999 1.9sdi.

It is happening often that when its heavy rain the engine rpm drop suddenly to approx 200 and the engine is almost dying, then after 10 sec it goes back to normal.

I was driving for 100 km during heavy rain and this happened more than 15 times.

Could you please tell where and why is this coming from??? Is there any damage that can happen to the engine???
Is there any connection with the engine air filter which is located at the bottom near the ground.

Thank you for the support.

[albyone]

Does it drop when you are moving? If so, how do you know when it happens as the engine will be engaged - therefore I would presume it would present as a loss of power?

Is the ECU getting wet? In my 6N2 it is under some pretty flimsy plastic under the wipers...

Does the throttle position have any effect on the problem?

Al

[Klevo]

It is dropping when I am moving, I know when this happens because the engine sound changes a bit (like it is dying) and I can see the rev drop in the dashboard (the rev drops to 200 rpm). Changing the throttle position will not make any benefit, after 10 sec it resumes normal condition, then it is repeated after some minutes again. Only during rainy whether.

I haven't checked the ECU (because I don't know where it is, I'll check the place you mentioned).

It is very irritating situation, I don't know what to do.

Thank you for the support.

[albyone]

By the sound of it, you are going to have to get the trouble codes off the car.... Have you got some diagnostic software?

[vc-10]

There should be an OBD port somewhere, I don't know where it is on the 6n but on the 9n it's under the dash on the drivers side. I'd assume it's there (or someplace similar) on the 6n too.

[Klevo]

I have connected the vag-com before, but know its going to be difficult because as I have mentioned this happens when I am driving, I might try to do this, I hope I am going to get something.
Is there any connection with the engine air filter that is located in a dangerous place at 6N1, that can get wet (I am getting scared a lot of this fact, I don't know if this can happen?).

[vc-10]

Not quite sure what you mean about the 'dangerous' air filter (not got a 6n!) but the car should store any codes that appear I think.

[albyone]

I have connected the vag-com before, but know its going to be difficult because as I have mentioned this happens when I am driving, I might try to do this, I hope I am going to get something.

You shouldn't need to check anything while driving, the ECU should log any faults (DTC's). It is these faults that you will need to get.

Is there any connection with the engine air filter that is located in a dangerous place at 6N1, that can get wet (I am getting scared a lot of this fact, I don't know if this can happen?).

If it is anything like my 6N2, no, it would be very unlikely that water can get up around the air filter. Why do you suspect it is a problem with something near the air filter?

[Klevo]

I don't suspect anything just guessing because I've heard a lot from different car services that you must pay to much attention with the air filter not to get it wet because that will kill your engine (and since I don't know anything from repairing I was just guessing).

Today it happened again on my way to work, when the rev dropped to 200 rpm there was a lot of white smoke coming out from behind, and the power of engine dropped also, than the same thing it was OK after ~10 sec.

I have another suspect, is there any connection with the v-ribbed belt, may be it is loose or anything and when it gets wet the friction with the pulley drops. I am just guessing until I get me vag-com soft and the cable.