2006 VW Polo - Idling problem

Soldato
Joined
27 Jul 2007
Posts
5,670
Hi all,

I bought a 2006 VW Polo 1.4 FSI Sport a short while ago with 53000miles on the clock and full VW service history. The car is on a long life service regime at the moment.

Last week I took it to a VW Specialist garage for a service and new brakes. I mentioned to them that the car sometimes jerks quite violently at idle but the revs don't drop. I said I thought it was the compressor for the aircon, but even if you turn the A/C, it still does it. The car drives absolutely perfectly apart from this one annoyance.

Sometimes after a violent jerk, the car will start idling just under 1000rpm. It doesn't feel any different and after a few miles the needle will drop back to its original +-850rpm.

They hooked it up to the VW diagnostics machines but the ECU wasn't reporting any problems. They disconnected one coil pack at a time and the engine reacted like you'd expect. They say that it might have dirty valves. I've tried a tank of super unleaded (97RON) this week to see if that might help, but no such luck.

Any other ideas guys? I'm really hoping they don't have to remove the head like they said they might.
 
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Soldato
Joined
4 Sep 2005
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6,423
Location
Whitwood, West Yorks
Throttle body. There will be a crankcase breather then vents into the airbox. Engine gunk comes through this to be sent through the combustion process, but it also covers the throttle body in gunk reducing its functionality.
 
Soldato
OP
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Ah, right! Thanks :) He did say that the air filter was quite clean for a car that's done 20000 miles since it's last service.
 
Associate
Joined
19 Sep 2005
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1,242
As above, try removing the throttle body and giving all the sensors, idle control valve etc. a good clean up with WD40. With the standard oil breathers you get a fine mist of oil going back into the inlet - it can/ does gunk sensors up eventually causing all sorts of strange issues.
 
Soldato
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Location
Whitwood, West Yorks
20000 mile service intervals cant be good. If you dont feel up to Leeums tb cleaning, you can just take the top of the airbox off, and spray carb cleaner at the tb whilst someone revs the engine.
 
Soldato
OP
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Posts
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20000 mile service intervals cant be good. If you dont feel up to Leeums tb cleaning, you can just take the top of the airbox off, and spray carb cleaner at the tb whilst someone revs the engine.

The car does mainly motorway mileage so the longlife service schedule seems to be working quite well for it.

My wife has a good friend that's a mechanic so I'll show him these suggestions and ask him to do the work. I'm carp at these sort of things!
 
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