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VW Polo 1.2 12V 2005 - Intermittent misfire #

Posted by Geoff Taylor on April 10, 2012, 2:01 pm

Year of Manufacture *: 2005
Engine Size and Code *: 1.2 12v bme code
( Optional ) ECU Type: siemens5wp

Hi

This car was presented after been recently bo ught at an auction, it suffers from intermittently running on 2 cyls,the owner got codes read which said no2 cyl coil fault and replaced the coil this hasnt cured it.
most of time it runs ok on 3cyls but usually at idle begins to misfire. When studying service history i noticed some handwritten note that the ecm had been replaced but its casing doesnt look new, there a signs that much other work has been done i suspect previous owner has decided to put it in auction after nobody been able to fix.
NB i have heard of other polo with same fault with no fix, before spending many hours trying to discover cause wuold appreciate any input.

GEOFF TAYLOR.

Re: vw polo intermittent misfire

Posted by Lee Mackintosh <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1348' width='330' height='300' border=0 style='border:none;'> on April 10, 2012, 3:01 pm, in reply to "vw polo intermittent misfire"
Lee Mackintosh

I had one of these in a few weeks back the exact same fault. Compression was down on 1 cylinder even though it was fairly high compresson (which i thought acceptable) it obviously wasn't.

Don't know the outcome as the customer (trader) was going to take the head off to ivestigate.

Seems they suffer with valve problems.

thanks
lee

Re: vw polo intermittent misfire

Posted by john womack <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2611' width='330' height='300' border=0 style='border:none;'> on April 10, 2012, 6:06 pm, in reply to "Re: vw polo intermittent misfire"
John Womack

Hi geoff

this engine is a problem we use bg induction cleaner with good results.
carbon seams to be the big issue making valves stick, weve replaced valves to find after 6 months or so to be nobetter if not run on top quality fuel & used for the supermarket run .

Re: vw polo intermittent misfire

Posted by Jon Morgan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3190' width='330' height='300' border=0 style='border:none;'> on April 11, 2012, 10:13 pm, in reply to "Re: vw polo intermittent misfire"

These are a troublesome design, VW have taken measures to rectify this fault with modified valve guides & engine software which alters the idle speed & fuelling strategy.
Reworking the head results in the fault returning.

hth.

Re: vw polo intermittent misfire

Posted by geoff taylor <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5467' width='330' height='300' border=0 style='border:none;'> on April 11, 2012, 10:44 pm, in reply to "Re: vw polo intermittent misfire"
Geoff Taylor

thanks for all your replies they all seem to be highlighting a inherant design flaw.
i would like Jon to clarify what he means when he describes reworking of cyl head and does the the remapping have to be carried out byVW dealer.
GEOFF

Re: vw polo intermittent misfire

Posted by Jon Morgan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3190' width='330' height='300' border=0 style='border:none;'> on April 12, 2012, 8:21 pm, in reply to "Re: vw polo intermittent misfire"

Hi Geoff,
by reworking the head I meant strip & fit new valve guides /valves etc.....
I've heard of the heads cracking after new guides have been installed & received too many reports off folk who attempt head repairs on the single cam 1.2 suffering misfire faults again.

I recently heard of one via another garage where the head had been sent to an engineers 3 x to resolve misfire issues.

Some of the above is covered in a lengthy dealer bulletin that involves testing everything in a long winded process & ends with, "if all of the above fails, replace the cylinder head"

We cut out the middle man - compression test when misfire is present, if any compressions are 15% off spec we fit a new head.

I can root out the bulletin & email it to you if you like?

The software update is a Dealer tool or Autologic user affair.

A couple of local workshops have fitted new heads & then sent them to us for the update to be installed.

Jon.

Re: vw polo intermittent misfire

Posted by Geoff Taylor on April 12, 2012, 10:44 pm, in reply to "Re: vw polo intermittent misfire"
Message modified by board administrator April 13, 2012, 1:17 pm

hi jon
i would appreciate your offer of e mail the bulletin my email address is on members database
thanks GEOFF TAYLOR.

Re: vw polo intermittent misfire

Posted by geoff taylor <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5467' width='330' height='300' border=0 style='border:none;'> on April 12, 2012, 10:53 pm, in reply to "Re: vw polo intermittent misfire"
Geoff Taylor

jon
previous post has me listed as UKAT5467 thought you may not reply if you didnt see my name.
ps does the 6v engine also suffer same as i own a skoda fabia with BMDcode engine.
geoff.

Re: vw polo intermittent misfire

Posted by geoff taylor <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5467' width='330' height='300' border=0 style='border:none;'> on April 13, 2012, 11:01 pm, in reply to "Re: vw polo intermittent misfire"
Geoff Taylor

thanks jon for email i have briefly studied it and hope it will help us, unfortunately i have never been able to understand vw!s block/channels way of showing data but rest should help. will probably get latest software loadead as current idle speed around 740rpm.
by the way misfire always detected cyl2 code16686 P0302 with Autodiagnos mt pro.
have noticed today horrible orange sealant evident at sump joint and all over top end of engine so some previous mechanical work must have been done possibly timing chain? which also appears to be a problem according to other posts.
(if only everything in life was as reliable as a volkswagen?)

geoff.

Re: vw polo intermittent misfire

Posted by Jon Morgan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3190' width='330' height='300' border=0 style='border:none;'> on April 14, 2012, 2:02 pm, in reply to "Re: vw polo intermittent misfire"
Jonathan Morgan

Timing chain slippage is common on the early 12V engine, pre 2005.
The slippers weren't large enough to hold the chain in place after an oil change this allowed the chain to drop off the bottom sprocket & then back into position as the oil pressure returned - clamping the whole lot in a mistimed mess.

"we've serviced your car sir, it now needs a new chain kit before it will ever run again"

Re: vw polo intermittent misfire

Posted by andyhyoung <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5148' width='330' height='300' border=0 style='border:none;'> on April 14, 2012, 5:27 pm, in reply to "Re: vw polo intermittent misfire"
Andrew Young

I have also seen,"we have fitted a new clutch,madam,and now it won't start".Turning the engine backwards from flywheel end causes chain to jump.

Re: vw polo intermittent misfire

Posted by Les Smith <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1209' width='330' height='300' border=0 style='border:none;'> on April 20, 2012, 7:29 am, in reply to "Re: vw polo intermittent misfire"
Leslie Smith

One of my most used tools may help isolate fault. Vac guage. An underused tool in my opinion. Just my thoughts.

regards
Les

Re: vw polo intermittent misfire

Posted by James Eardley <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3143' width='330' height='300' border=0 style='border:none;'> on April 20, 2012, 1:35 pm, in reply to "Re: vw polo intermittent misfire"

Hi Geoff

I havn't had time to read all the other posts so forgive me if I am repeating anything.

I have done a couple of these now that have had cracked and burned out exhaust valves.

There is a gentle miss fire until the ecu decides the particular cylinder is not contributing enough power and cuts the injector to that cylinder leaving a definate misfire.

You need to do a compression check.

A cylinder leakage test will normally show the problem up.

Also if you put the offending cylinders piston to BDC and feed a boroscope down the plug hole with a piece of cotton tied to the end of the camera. You can pull the cotton and face the camera upwards onto the valves and have a good inspection of the valves.

If all these tests pass I would preferably scope the ignition and injectors.
Or, swap the offending cylinders injector with another cylinder. Same with the coil pack and plug and see if the code moves cylinders.

hth
James

Re: vw polo intermittent misfire

Posted by geoff taylor <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5467' width='330' height='300' border=0 style='border:none;'> on April 28, 2012, 11:52 am, in reply to "Re: vw polo intermittent misfire"
Geoff Taylor

UPDATE
the polo has been treated with 2 cans of forte gas treatment,then been to vw dealer for the software update and idle speed increase.
they confirm probably a compression related fault as suggested by most of posts (thanks all for leading me to cure)
at moment all seems well but if reoccurs a decision will need to be taken on further work required and subsequent costs.
thanks all again

GEOFF.

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