2.0 lumpy idle

[simonsaunders]

Hi,

Just looking for some pointers really. I've got a 2000 2.0 Octavia, 72k, FSH, etc. and it is not idling properly. It is fine when I start the car as it revs a little higer (900 - 1000 rpm), but once it has warmed up the idle drops to 700(ish) RPM and then it is well lumpy. It sounds like it misfires and drops a 200-300 RPM and then recovers. It does this every 2-3 seconds (so it is not misfireing every revolution).

If I increase revs (either static or once moving) ever so slightly it seems to be OK - no misfires higher up the rev range.

Changes the plugs and leads to no avail, although it is a bit better. Optimax or BP Ultimate helps too.

I do not know if it is related, but if the revs drop (e.g. change gear, come to a stop, etc.) the revs drop right down to 400-500 and then come up again to a lumpy idle.

I'm at a bit of a cross road really... do I:

a: replace the coil pack

b: change something else - like the throttle position sensor (maybe the reason why the revs drop, but then recover?????)

c: send it to the dealer for some diagnostics and pay through the nose...

Any advice will be appreciated!

Si

[cheezemonkhai]

Can you adjust the fast idle speed like you could on the old carb cars?

[Tech1e]

Sounds like a faulty throttle valve. But emissions faults are common on the 2.0.

Any fault codes?

[simonsaunders]

I don't think that you can adjust the idle - I understand that it is all tied up in the ECU?

The engine management light does not stay on once the engine has started - does this imply that there are no fault codes?

[Mil]

It shouldn't be at 700rpm in idle, thats too low. The 2.0 does shudder normally, at somethin like 850-950 rpm, but below that, it sounds like you have a problem.

[spiggotpaddy]

try some carb air intake cleaner on the throttle valve, it could be just sticking a bit.

[r.carder]

Mine did that but plug leads sorted it. I have had problems after 2 services like this.

I hope you get it sorted, let us know.

Regards

Roger.

[simonsaunders]

Hi all,

As I started this post, I thought that I best bring it all to a conclusion! I've been charging around on my two wheeled death trap (Fazer 600) and not thought too much about cars, and certainly not bothered fixing my Octy. Until now. Oh, and it got worse - low revs with full throttle was really jerky and pulling away was a pain - unless I gave it lots of revs it bogged down sooooo easily.

I got some mixed messages from fellow posters - I'm not knocking what anyone said, it just that there wasn't a common theme so I didn't know where to start. Out of sheer laziness I decided to pass it over to a pro and get them to sort it. I spoke to James at the Kent VW & Audi Centre (Kent VW and Audi Spares) they do spares, but also work on cars from the VAG. Rather than take the car in, he said that he was 99% sure that it was the butterfly in the throttle body that was gummed up and generally not moving like it should, and that I should try to sort it out myself but if I have no joy to drop it over.

His advice was to disconnect the pipe work from the throttle body (really easy - start with the airbox and follow the ducting back until you get to something metalic at the rear of the engine - that is the throttle body) and then with the engine running to skirt small amounts of carb cleaner into the butterfly (the small 'flap' that moves).

I did this, and opened/closed the butterfly whilst doing so. I think that it got about 30 blasts of carb cleaner, about 1 second in length, over a 15 minute period.

And now it is fixed! :-) :-) :-) :-) :-) :-) :-)

It runs just as it should - nice stable idle, feels crisp at all RPM - good as new!

So a gold star for James @ Kent VW and Audi Spares - it is nice when someone is genuinely useful rather than just taking your cash.

Looking over the thread, Lummox got close, but Spiggotpaddy got it spot on! Apologies for not following your advice sooner...

Si