problem with daughters Car.

[glennjamin]

Yet again I need the assistance of the PH VW forum.

Daughter's first car a 2005 VW polo 1.2 petrol. Been good as gold until recently. Drives really well but engine management light came on and felt like it's lost power. To level that it creept along hardly making progress.

Been in garage and fault finding came up with 2nd cylinder coil pack faulty. Has been replaced and fault cleared. Has been great but yesterday after 2k easy driving engine management light came on again?

Any ideas ? Before I book it in again....

Thanks in advance

[Hammer67]

2000 miles since the last fault?

Almost certainly unrelated and is a new problem.

Scan it for codes.

[cuprabob]

Assuming all the coilpacks are of a similar age, it could quite simply simply be that a coolpack on another cylinder has failed but until the fault code that's triggering the EML is read it's guesswork.

[Belle427]

Or it was a cheap and nasty coil pack that has failed again.

[cuprabob]

Belle427 said:

Or it was a cheap and nasty coil pack that has failed again.

Yes, there is that possibility too

[glennjamin]

Sorry for delay in responding to comments. I've ill for a few days.

But this morning decided to replace all coil packs as fault code was 16686 on scan.

Did this replaced with Delphi coil packs and new set of NGK plugs.

Took for test drive running really smooth for 3 or 4 miles then engine management light came on loss of power struggled to get back.lifted Bonnet checked cables to see it lose connection no difference wriggling wires ! stiil seems to be only firing on 2 cylinders. Scanned came up with same code. Cleared and runs ok again.

Any idea why having replaced all coil packs and plugs still got same fault code ?

Thanks in advance !!

[Belle427]

That code seems to suggest it’s a misfire on cylinder 2 so if you have chased the spark area then I’d be checking the injector first as a next step.
Probably a good idea to do a compression check too.
What was the original trouble code?

[TedStriker]

Compression check before anything else

[Jordie Barretts sock]

TedStriker said:

Compression check before anything else

Surely this points to electrical rather than mechanical? If there was low compression on a cylinder(s) then it would miss from the off, not 3 miles into a journey?

[996Keef]

Probably:

Burnt exhaust valves

Worn rings.

Worn timing chain

Or a combination of all 3

Usual 1.2 polo problems

What did the old plugs look like? f they're black and oily it's time for a rebuild

[glennjamin]

Plugs we clean no oil, not blackened were virtually like new. Originally when returned to garage head was thought to have been a problem so was removed and checked valves and seals were ok. ECU was also sent off.

Totally puzzled by this one.

[aka_kerrly]

glennjamin said:

Sorry for delay in responding to comments. I've ill for a few days.

But this morning decided to replace all coil packs as fault code was 16686 on scan.

additional information about the fault code from the RossTech site:

VAG Error Code: 16686/000770/10592
EOBD II Error Code: P0302

Fault Location:
Cylinder 2 - Misfire Detected

Possible Cause:
Malfunction Indicator Lamp (MIL)(K83) active.
Lack/loss of power.
Hard start.
Engine hesitation.

Wiring/Connector(s).
Ignition system.
Fuel injectors.
Fuel pressure.
Running out of fuel.
EVAP canister purge valve.
Evaporative emission system.
Low compression.
Base engine problems.
Engine Control Module (ECM) damaged.

Special Notes:
This feature search for engine misfire in a specific cylinder. Most of the time the cause for a misfire is a lack of combustion in a cylinder due to absence of spark, poor fuel metering, or poor compression.

Tech Notes:
The P0302 code means that the cylinder 2 is misfiring or is randomly misfiring. Start by checking for intake leaks an if no leaks are found the next step is to replace the spark plugs on cylinder 2. If the problem persist more tests needs to be done to diagnose problem.

Description:
When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position Sensor signal to vary, the Engine Control Module (ECM) can determine that a misfire is occurring.





Hope this gives you a few pointers on some more free/easy checks you can do at home before committing to getting a compression test done.

[Matt_E_Mulsion]

1.2 TSi normally = Stretched Timing Chain

[the-norseman]

Matt_E_Mulsion said:

1.2 TSi normally = Stretched Timing Chain

2005 doesn't have a TSI engine.

[glennjamin]

Thanks guys you're absolutely awesome. Can always rely on this forum for help. Looks like I've got some busy time to investigate more.

Merry Christmas to you all !!

[catso]

cuprabob said:

Belle427 said:

Or it was a cheap and nasty coil pack that has failed again.

Yes, there is that possibility too

My Son had a 2004 1.2 Polo, we got it cheap (£200) because it didn't run. Problem was a faulty coilpack that had also taken out the ignition fuse.

I fitted a new coilpack and bought the cheaper one (the coilpack with no name) to save a few quid and all was well for a few months when it failed again so obviously it wasn't up to much.

Replaced it with the better quality version and it was fine for a good few years. Sadly the car was written off this year due to excessive rust on the sills etc. making it uneconomical to repair (though it was great mechanically).

On the plus side, the local breakers paid £351 for it...

[Matt_E_Mulsion]

the-norseman said:

Matt_E_Mulsion said:

1.2 TSi normally = Stretched Timing Chain

2005 doesn't have a TSI engine.

Fair point!!!

[cslwannabe]

What fuel does it typically use? I still hear the odd story of engine woes on supermarket UL. Never sure whether an urban myth but my petrolhead mate experienced it on his M140. He was advised to switch fuel and never had any more issues.

[glennjamin]

Normally put momentum at Tesco haven't had a problem only use Tesco's as 1/2 mile from home. But might try BP ultimate.....

[cslwannabe]

Should be fine with momentum - ran my first golf R on that for long periods and no issues.

Presumably it gets a decent run every now and again? And you’ve tried an Italian tune up, once its up to operating temperature?

Had a misfire on my Boxster recently - coil packs the issue. Only happened at low revs and for such short periods it logged no codes.