Polo 6n2 misfire at idle?

[Waynepolo]

So I've got a polo 6n2 1.0, 51 plate, a touch over 40k on the clock, full service history from a vw garage, and it's misfiring at idle. It won't do it all of the time, and it runs fine when you put your foot down, but at idle it will rev anywhere between 1000 and about 500, and will feel like its juddering off load. It had a new coil pack put on 200 miles ago, and I've just changed the leads and plugs, but it's still happening. Does anyone have any suggestions for this? Thanks

Wayne.

[alexperkins]

Get a can of carb cleaner, and clean the throttle body out per the instructions on the bottle. Wynns Fuel Intake and Carb cleaner from halfords is one of the best ones to get (in a big purple can)

If that doesnt fix it, check out the vacuum hose that goes from the throttle body to the brake servo as this has a tendency to split causing irregular idle.

[Waynepolo]

Took the air box off, cleaned a lot of the gunk out of the throttle body, now looks like a mirror. Checked all the hoses anyway, no splits or holes or loose connections... Started it up and a big belch of white smoke came out, probably the cleaner burning off. It runs a little better, is a lot less jumpy at idle, but it will still only tick over at 500 rpm... Is this normal for a 1.0 6n2?

Thanks.

[alexperkins]

Have you sprayed some carb cleaner into the engine whilst it is running like the can describes? Its important to do that as it clears out the inlet manifold

Tickover for a 6N2 is 750-800RPM

Have you had the car scanned with VCDS?

It could also, bizarrely i know, be a fault with your alternator. I had this on mine, and once it was replaced, the problem went away.

[Waynepolo]

A friend of mine scanned it. Cylinder 1 misfire, cylinder 3 misfire, random multiple misfire, max engine RPM exceeded ***WARRANTY VOID***.... teaching the girlfriend to drive, slams it from 4th to 1st at 30... could be the cause of the last warning.

Had the codes wiped, and the cylinder 1&3, and random multiple misfire still came up.

Yeah I did spray it in there, there was probably a fair amount of cleaner left inside the throttle body before I started it up, as it took a few attempts o start back up (is this a problem?)

[alexperkins]

What I meant was did you spray it in there whilst the engine was running. The engine would start to choke but you just give it more gas and it'll keep running. This properly blasts it out

I would get a compression test done if that doesn't sort it.

[Waynepolo]

Oh, no... Where do I spay it in?

[alexperkins]

Directly into the throttle body mate

[Waynepolo]

I did spray it in there, but not when it was running. I had to take the air box off to get to the throttle body so I can't start the car with that off, can I?

[alexperkins]

Yes, its fine to run it with the airbox off for the purpose of cleaning it.

[x3D]

I've just resolved this issue on my polo.
You need to replace the lambda sensor, which will cure the rough running, and replace your brake cervo vacuum pipe. I can put money on that pipe being split. It was even a recall at one point.
Ignore everyone saying to put stuff in your throttle body, that's all fine.
Lambda sensor, and brake cervo vacuum pipe. It'll be about 70 to 100 pounds altogether.

[TRiBaL]

I've just resolved this issue on my polo.
You need to replace the lambda sensor, which will cure the rough running, and replace your brake cervo vacuum pipe. I can put money on that pipe being split. It was even a recall at one point.
Ignore everyone saying to put stuff in your throttle body, that's all fine.
Lambda sensor, and brake cervo vacuum pipe. It'll be about 70 to 100 pounds altogether.

Which sensor? Pre cat or after?