Hello

For the last few months when I draw up to traffic lights or a roundabout my 2000 Octavia 20V 1.8T has been idling terribly at sub or around 1000 rpm. The fault is intermittent but has been gradually getting worse and worse to the point where it now sometimes cuts out completely. I have found that when the idling is particularly wayward, the accelerator pedal actually moves up and down without me touching it all.

Does anyone know what is wrong here? Has anyone experienced the same symptoms with their 1.8T? I thought it might be the throttle-body but I didn't want to start taking things apart, until I got a 2nd opinion. The car has done 109K.

Any help would be greatly appreciated, as it is now starting to do my head in a bit.

Regards

Ian

Throttle body clean is an obvious and easy place to start. I did mine and the car now idles nicely around 800rpm. 109k is a good mileage to gunk up the body.

It's an easy job (4 bolts, bit of carb cleaner and a new gasket from Skoda for £1.20).

I put a brick on the accelerator to keep the throttle open so I could get in and around it for a good clean. Just have to remember not to disconnect the electric connectors so you don't need to reset the throttle.

If that doesn't work, then maybe new sparks?? Someone else with far more knowledge than me should be along soon to help.

Good luck

Could also be the infamous breather pipes under the intake manifold... is the front of the engine slighly oily?

Sounds like a very similar problem to mine.

My TB was cleaned approx a year ago, but will give that another go.

Have checked over all of the boost pipes and can't see any obvious signs of failure :(

My though was that maybe the idle control valve was reading funny or the throttle position sensor was dodgy...

It sounds like an idle control problem to me, not least because 1000rpm is way too high an idle in my experience; I'd expect an engine to idle at 750 to 850 (dependant on type).

i had same problem i disconnected my maf an it ran better so i cleaned it an it ran ok, just a thought

every little helps:thumbup:

Which engine does your car have? If an AGU, the idle speed should be 860 +/- 100 rpm. If an AUM, then it is 760 +/- 100 rpm.

As Colin said it could well be the vacuum pipes under the inlet manifold, a high idle speed sounds like an air leak to me.

Could also be the infamous breather pipes under the intake manifold... is the front of the engine slighly oily?

Not checked that yet, will do so tomorrow in the daylight

Which engine does your car have? If an AGU, the idle speed should be 860 +/- 100 rpm. If an AUM, then it is 760 +/- 100 rpm.

It is an AGU.

In my original message I said "my 2000 Octavia 20V 1.8T has been idling terribly at sub or around 1000 rpm".

This was probably a little inaccurate, what actually happens is the idle speed seems to dip really low (100-200rpm) then suddenly goes high again (1000-1200 rpm) and keeps doing it until it either evens itself out to around 800-900 rpm (as you would expect) after 10 seconds or so or completely cuts out. When the needle is moving up and down wildly, the accelerator pedal is also moving completely of it's own accord. Sometimes my headlamps dim slightly in time with the needle moving up and down as well.

Cheers

Ian

Mines an AUQ

Whilst it averages an idle of 800rpm it dips to around 5-600rpm when pulling up and then varies to up 1000rpm until it settles down again to 800rpm.

It sounds like a similar issue to Tik's, but mine doesn't cut out.

I'm not aware of the throttle pedal moving but i'll check that this evening.

Is there an idle control valve somewhere that can be changed?

Mines an AUQ

Whilst it averages an idle of 800rpm it dips to around 5-600rpm when pulling up and then varies to up 1000rpm until it settles down again to 800rpm.

It sounds like a similar issue to Tik's, but mine doesn't cut out.

I'm not aware of the throttle pedal moving but i'll check that this evening.

Is there an idle control valve somewhere that can be changed?

Mine seems to have the same idling problems too although there is a low down power issue when this happens. AUM engine

I know htis post was 2 years ago but has anyone found the solution, mine has just started with all these symptoms, im gunna clean the throttle body and maf sensor, where is the idle control valve located? my 2002 octavia vrs has just ticked over to 119000 miles so im looking at replacing things now rather than just cleaning them,

cheers,

Clean the throttle body. Check to see if you have the old black coolant temp sensor, if you have replace it with a genuine VAG revised green one.

Like above, start with TB clean as its cheap and easy (although somewhat messy) then after that you are looking for a VAC leak, loads of guides on how to locate these if you search