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VW Polo 1.2 2006 - Engine misfire, code P0301 - Fixed #

Posted by John Fletcher on October 29, 2014, 3:15 pm

Year of Manufacture *: 2006
Engine Size and Code *: 1200
( Optional ) Scanner Used: vag com/ kts/ solus ultra
( Optional) Fault Codes: PO301

Can anyone help on this one engine misfire on no 1 cylinder, before it came to us it had 3 bosch coils and plugs and a new injector. The compression is ok when it misfires the voltage shuts off on no1 cylinder which i presume is the ecu shutting the injector down, when it misfires if you turn the engine off and start it again it is ok.

The car has been in to the main agents and they have said they need 6 hours to diagnose the problem we have fitted a new servo pipe that was leaking after doing this the vehicle ran fine for a week then started missing again any suggestions John

Re: vw polo engine misfire

Posted by Chris Angus User icon on October 29, 2014, 3:51 pm, in reply to "vw polo engine misfire"

Worn valve guide would be my best guess, well known problem on these engines.

Re: vw polo engine misfire

Posted by Pete Mutlow User icon on October 29, 2014, 6:15 pm, in reply to "Re: vw polo engine misfire"
Peter Mutlow

Yes...Agree with Chris. I posted something about this about a year or so ago. The ECU "sees" the misfire and can be seen in live data in the misfire counter. A known problem and a compression check may well prove the point.

Regards

Pete M

Re: vw polo engine misfire

Posted by John Fletcher User icon on October 30, 2014, 10:14 am, in reply to "Re: vw polo engine misfire"
John Fletcher

Hi Chris and Pete
Thanks for the input I agree with your thoughts its just the fact that it drove perfect for a week i have got to start somewhere so its head off will let you know the outcome cheers John

Re: vw polo engine misfire

Posted by Andy Broomhead User icon on October 30, 2014, 8:27 pm, in reply to "Re: vw polo engine misfire"
Andy Broomhead

Sorry but has a compression test ben done?

Re: vw polo engine misfire

Posted by Steve Sneap User icon on October 31, 2014, 8:22 am, in reply to "Re: vw polo engine misfire"
Stephen Sneap

We had same problem a couple of years ago .Found badly pitted valve seats ,fitted new valve but a year later and 5k came back with exactly same fault .VW said it should have a new head only way to fully cure.....if you repair advise customer of this!
Timing chains are also an issue....
Also is owner using supermarket fuel?
Steve Sneap

Re: vw polo engine misfire

Posted by Craig Hewison User icon on November 3, 2014, 8:29 pm, in reply to "Re: vw polo engine misfire"

i had this a couple of years back and the misfire was only counted above 4000rpm, measured running compression with WPS500 over a long timebase and you could quite plainly see the cylinder compression drop with rpm increase. We advised customer of known issue, VW recommend a modified cylinder head and software update but i have heard that a good engine shop can sort it by other means (who knows). Either way, in our case the customer didn't want to spend the money and that as they say was that!

HTH
Craig

Fixed #

Posted by John Fletcher on November 18, 2014, 4:46 pm, in reply to "VW Polo 1.2 2006 - Engine misfire, code P0301 #"
Edited by board administrator November 19, 2014, 2:50 pm

Thanks for the input we removed cyl head and found no 1 valves leaking re-cut seats and valves rebuilt and everything ok after 350 miles we have warned the customer that if the fault re-occurs then a new head is required.

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