V5 170hp Open Circuit on Cyl 2

Calling all V5 Tech specialists, this is officially a mayday...

Ok, this is the history of this fault.  
First off, started getting an intermittent misfire which would clear itself up then come back again randomly dependent on how long you drove the car for.  
Initially thought it could be a blocked injector or gank in the injector rail.  Poured approx 1.5 litres of Redex through the system over multiple fill-ups with no real change to the problem.
Next replaced all coil packs and spark plugs, again with no resolution to the problem.
Then decided to purchase a 2nd hand injector online and take it to a local recommended VW specialist to install.
They installed, problem still there.  Problem was, they never swapped injectors over to see if the problem moved or not.
So now we're at the most recent work done.
Took off the manifold and removed potential problem injector, tested the resistance on a multimeter and it was fine at 14.5ohms.  Placed a bit of twin and earth on the contacts of the injector and the battery terminals and it happily clicked away.  Multimeter tested the injector plug with ignition on, and again, found there to be a voltage reaching the cyl 2 injector.  In addition tested all other pairs of cables feeding the injector rail and they are all receiving current as expected.
Swapped two of the injectors around, now knowing they are all good, hoping for the problem to move to another pot.  Replaced and started the engine, only to find the problem still exists on cyl 2.  And my trusty £15 handheld diagnostic machine confirms this, and that all other sensors appear to be 'ok'.

So this is where my knowledge ends, and where most forums have little to no further information on what to test/replace/check next after these items have been looked into with this outcome.

So I put it to my fellow V5 owners, in the hope that someone has had similar issues or gone down the same road and found the same head scratching problem.

Any sound advise on any sensors to replace/look at or ignition amp to look at or whether the issue is likely to ultimately lie with the ECU and whether it's worth chasing the fault down at all would be greatly appreciated.

I love my V5 and will do almost anything to keep him going as other than the misfire, it's a sound motor that has never let me down.

I now put myself in your hands...

Fingers crossed Buddy, someone reads this and can help !
Am naff on electrics sorry   

Hi mate, I had 2 long weeks of trying to find the reason why my AGZ 150bhp V5 randomly misfired. I tried everything. New HT leads, coilpack, sparks, injectors. In the end I looked at the ignition amplifier. I found one on EBay for about £20 and hey presto was fine after that. It is a common fault apparently. Is definitely worth looking at and if it doesn't fix it you will get your money back on the part if you relist it.

You're a star! Ok that's the next port of call then. Could you advise me on where to locate the little bugger and how easy it is to replace. Any pointers would be greatly appreciated!

Again many thanks for potentially putting me and my V5 out of their misery

Sorry to say buddy, the 170 doesn't have an ignition amp, just the 150 does.
but read below, sounds the same problem you have   

http://uk-mkivs.net/topic/17426-golf-v5-agz-misfires-on-one-cylinder-solved/

Yep, after reading the response from R444SPY, which is still appreciated btw! checked a few parts suppliers to find just that.

Strangely came across that post too Welshie, in my part hunting travels yesterday.

Well I've bitten the bullet and ordered up a crank position sensor in the hope that's the culprit. Already had the front off the car to look at the injectors, so should hopefully be a painless install.

Not sure I want to go messing about with the ecu connectors though as that post suggests, as I've read that disconnecting those results in the basic settings to the ecu being lost and requiring the dreaded VW Main Dealer intervention, which I want to avoid at all costs. If you know differently I'll give them a wiggle.

Will keep you posted with progress.

P.S. Just noticed that a local work dodger has had a go at trying to remove my windscreen and cracked it from the edge all the way down the drivers viewing area, so another thing to add to the list!

The crank sensor cost much ? hopefully it sorts it

Ah yeah, forgot the 170bhp V5 doesn't have one.
Hopefully the crank sensor sorts you out mate, fingers crossed for you.

Well I can get a genuine crank sensor from TPS at £81+vat, but I can find others that I'm guessing aren't genuine Bosch parts for far less, around £19 from ebay or £48.50 from Motorpart, also ebay..

My guess is, if I go for a non OEM part it'll either resolve the problem, but not for long, or not resolve the fault at all. Anyone have any recommendations as I haven't spent out on the part yet.

Best off getting the genuine 1

Ok, problem sorted and engine running sweet as a nut again.

All it ended up being was the ecu connector (the one on the right as you look from the front of the car). Never got as far as replacing the crank position sensor.

Turned out that the retaining clip had bumped loose which forces a good connection to the ecu unit. A little lift with a screwdriver threw the vent immediately resolved the misfire, and I knew at that point I'd found the fault. Nothing else needed to replaced, no parts, sensors or connectors.

The only struggle was getting the central wiper arm motor off which resulted in an emergency call to a mate who I knew had a wiper/battery terminal puller. Once removed could take trim off and get easy access to the ecu connectors. There's a sliding clip that runs along the back of the removable connector on the right, and by design it forces the connector to engage with the ecu male connectors, it had simply slid far enough out to cause a bad connection, and also explained the intermittent issue.

So for anyone else that happens to have a similar problem, I'd advise checking that first before spending any money. Could have saved £100's in diagnostics, coil packs spark plugs and crank sensor, and could have had it sorted in a day!

I hope this helps anyone else out with similar issues on their AQN 170HP V5, man finally won over machine!

One chuffed V5 owner signing out...

P..S. Anyone want a brand new unused crank position sensor (Vemo) paid £41 for it, should have been £62, sensible offers accepted

Glad its all sorted.. Party time