Diesel Injector Loom/Harness Replacement

V

vkx245l

A2OC Donor
Well as much as I wanted it to be a dodgy fill up or a bunged up filter I knew it was the injector loom that was giving up, so I bit the bullet and got down to changing it this weekend. I had a good search on here but couldn't find a "how to" guide so here it is - I also thought it was time I gave something back to this forum as I'm forever using it as a reference manual

Part number 045 971 600 £57.00 inc VAT (August 2012 prices)

Summary of work required: remove rocker cover, unplug harness and replace.

Caution: When removing and replacing the windscreen wiper (I'll explain later) BE CAREFUL. There are plenty of posts on here about cracked windscreen from the lightest of touches from the wiper arm to the glass.

You need to remove a few items to get to enough room to remove the rocker cover (should that be camshalft cover?)
Wiper arm
Washer heads
Air intake

The removal of these are covered in pages 5 to 7 of the TDI cylinder head pdf attached

Once these are removed un bolt the rocker cover. the bolts at the from and on top are obvious. There are, however, three at the back that you will have to remove blind. Image 294 shows a 10mm 1/4" socket on a screw handle attached to the bolt in the middle, the one to the left is no too bad but the one on the right is difficult to get to as there is pipework above preventing vertical access. I used a flexible connector on a 10mm 1/4" socket but a shortish extension turned with molegrips might work.

Unclip the cambelt cover on the left (clips back and front) to enable the rocker cover to release vertically. Never prise of with a screw driver but hit gently with a soft faced mallet or similar if it seems stuck. The gasket is reuseable, so be careful, wipe clean and reuse!

The harness is now visible (image 295)

The harness is held in on the right hand side with 2 10mm bolts. You might find the one you can see is captured behind the bracket for the pipes which run in front of the rocker cover just un bolt it to fully reveal the bolt you need to get at.

Unclip the harness from the injectors and withdraw to the right. You will need to compress the clips so that it slides out. I found one ofthe clips needed to be compressed on both sides to go through the machined hole in the head.

As they say in all good manuals - refitting is as above in reverse!

On inspection of the old harness I could see that one of the wires was pinched and had gone through the insulation - so be careful not to replicate this!

Good luck, take it easy and be methodical, give yourself 4 hours and it'll only take two.
On reflection I'm not sure the wiper arm has to be removed but you do need to get under the trim to access two torx screws which hold the air duct up. Wiper arm removal can be a disheartening first step if it doesn't want to play ball, if so you may need a puller.
 

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Good thread - I had to do this a while back - those bolts at the back are a right PITA! I agree you're best to remove the wiper arm. I didn't have pullers but mine came off ok anyway.
 
Nice write-up. I'll move this to the 'How To' section of the forum so its easier to find

Cheers Spike
 
Excellent write up of ‘how to’. Mine is idling
very rough at the moment. It becomes smoother at anything above idle. I am gonna try this first. Any thoughts on worn camshaft option? May even be shot engine mounts.
vkx245l said:
Well as much as I wanted it to be a dodgy fill up or a bunged up filter I knew it was the injector loom that was giving up, so I bit the bullet and got down to changing it this weekend. I had a good search on here but couldn't find a "how to" guide so here it is - I also thought it was time I gave something back to this forum as I'm forever using it as a reference manual

Part number 045 971 600 £57.00 inc VAT (August 2012 prices)

Summary of work required: remove rocker cover, unplug harness and replace.

Caution: When removing and replacing the windscreen wiper (I'll explain later) BE CAREFUL. There are plenty of posts on here about cracked windscreen from the lightest of touches from the wiper arm to the glass.

You need to remove a few items to get to enough room to remove the rocker cover (should that be camshalft cover?)
Wiper arm
Washer heads
Air intake

The removal of these are covered in pages 5 to 7 of the TDI cylinder head pdf attached

Once these are removed un bolt the rocker cover. the bolts at the from and on top are obvious. There are, however, three at the back that you will have to remove blind. Image 294 shows a 10mm 1/4" socket on a screw handle attached to the bolt in the middle, the one to the left is no too bad but the one on the right is difficult to get to as there is pipework above preventing vertical access. I used a flexible connector on a 10mm 1/4" socket but a shortish extension turned with molegrips might work.

Unclip the cambelt cover on the left (clips back and front) to enable the rocker cover to release vertically. Never prise of with a screw driver but hit gently with a soft faced mallet or similar if it seems stuck. The gasket is reuseable, so be careful, wipe clean and reuse!

The harness is now visible (image 295)

The harness is held in on the right hand side with 2 10mm bolts. You might find the one you can see is captured behind the bracket for the pipes which run in front of the rocker cover just un bolt it to fully reveal the bolt you need to get at.

Unclip the harness from the injectors and withdraw to the right. You will need to compress the clips so that it slides out. I found one ofthe clips needed to be compressed on both sides to go through the machined hole in the head.

As they say in all good manuals - refitting is as above in reverse!

On inspection of the old harness I could see that one of the wires was pinched and had gone through the insulation - so be careful not to replicate this!

Good luck, take it easy and be methodical, give yourself 4 hours and it'll only take two.
On reflection I'm not sure the wiper arm has to be removed but you do need to get under the trim to access two torx screws which hold the air duct up. Wiper arm removal can be a disheartening first step if it doesn't want to play ball, if so you may need a puller.
Click to expand...
 
Chris Warren said:
Excellent write up of ‘how to’. Mine is idling
very rough at the moment. It becomes smoother at anything above idle. I am gonna try this first. Any thoughts on worn camshaft option? May even be shot engine mounts.
Click to expand...
I would look at dogbone mount etc first, the injector loom typically makes the PD engine a non-runner. If you have vcds you can also check injector correction with the car warmed up. You can take off the valve cover to inspect the cam, any wear to the cam lobes will be obvious because the chamfer on the edge of the lobe will be worn down and look very sharp. I doubt that's your problem though.
 
I've attempted to tackle this today and spent 2 hrs getting to the part where I can access the rocker cover bolts. I can access all except the back right one - what a PITA.

Can anyone advise the best way to remove it? I'm assuming a 'flexible connector' is like one of these HERE?

I can get a socket on it with a small extension bar but then you haven't got enough room to add the driver on the extension or get mole grips to turn it. Access from the back looks impossible.

The good news is I can put it all back together in 20mins :rolleyes:
 
Foghorn said:
I've attempted to tackle this today and spent 2 hrs getting to the part where I can access the rocker cover bolts. I can access all except the back right one - what a PITA.

Can anyone advise the best way to remove it? I'm assuming a 'flexible connector' is like one of these HERE?

I can get a socket on it with a small extension bar but then you haven't got enough room to add the driver on the extension or get mole grips to turn it. Access from the back looks impossible.

The good news is I can put it all back together in 20mins :rolleyes:
Click to expand...
Take the EGR valve off, easy job. Then you can get over the screws to remove and torque up correctly.
 
Thanks I'll have a look at the EGR. Whilst I'll take the job on I'm still wondering if this is the actual culprit given the lumpy/stuttering happens at constant road speeds and it is perfect at idle? I've just had a look though one of my old posts HERE where the car is now doing exactly the same as it was at 150k (now on 180k) so I can almost certainly rule out the fuel filter as that was clean last time and this one is only 30k miles in. Last time the garage 'cleaned' the loom connectors amongst changing the intercooler.
 
Foghorn said:
Thanks I'll have a look at the EGR. Whilst I'll take the job on I'm still wondering if this is the actual culprit given the lumpy/stuttering happens at constant road speeds and it is perfect at idle? I've just had a look though one of my old posts HERE where the car is now doing exactly the same as it was at 150k (now on 180k) so I can almost certainly rule out the fuel filter as that was clean last time and this one is only 30k miles in. Last time the garage 'cleaned' the loom connectors amongst changing the intercooler.
Click to expand...
Delete the EGR and see if anything changes. Pull off the vac pipe and plug with a cycle valve cap.

Edit once off I cleaned up carbon deposits using a bottle brush and brake cleaner. Wear gloves etc the resulting black slop stains quite badly.
 
Easy way to check the loom:

1.4 tdi ATL lumpy rough rocking tick over running video

Hello, The engine (138K) rocks alot on tick over (warm or cold) and sounds really rough to me, having never had an A2 to compare against I thought the 3 cyclinders was reason. However having seen video of the 1.4 tdi for sale today on market ( what a beauty) with that ticking over smoother...
www.a2oc.net

Also check the connection to the loom. It was found (after I sold the car!) that the connection on my Lupo 3L had rubbed against something that had rubbed away all the insulation. This resulted in an intermittently smokey exhaust and oil dilution.

RAB
 
philward said:
Delete the EGR and see if anything changes. Pull off the vac pipe and plug with a cycle valve cap.

Edit once off I cleaned up carbon deposits using a bottle brush and brake cleaner. Wear gloves etc the resulting black slop stains quite badly.
Click to expand...
Touching on what Phil has mentioned above I'm more of a mind to point to the EGR rather than the loom. Reasons being:
  1. The hesitation lumpiness seems to occur more when the car is cold or has been stood for a few hours and cooled down a little.
  2. The idle is rock steady and the engine will free rev in neutral without any hesitation
  3. Under load there is no hesitation at all, it pulls like a train even immediatley after the stuttering
  4. Hesitation/stuttering only occurs at a constant throttle ie what you are using just to maintain a constant steady speed 30mph etc.
  5. If it was the loom then I'd expect more regular issues?
So, first off is the EGR 'delete' just a simple job of taking off the vacuum pipe and plugging it or do I need to do anything else like clean out the EGR?
 
Chris Warren said:
Excellent write up of ‘how to’. Mine is idling
very rough at the moment. It becomes smoother at anything above idle. I am gonna try this first. Any thoughts on worn camshaft option? May even be shot engine mounts.
Click to expand...
Hi Chris, I know this was a while ago now, but I was wondering whether you got to the bottom of your rough idling problem? Cheers, Dave
 
DaveySprocket said:
Hi Chris, I know this was a while ago now, but I was wondering whether you got to the bottom of your rough idling problem? Cheers, Dave
Click to expand...
Hi Dave, the problem in the end was the ‘dog bone’ stabiliser underneath that goes between the crossmember and the gearbox. The old one was shot. The engine would shake at idle, increase the revs it would smooth out. After changing it, the difference was incredible. A few weeks ago I changed the injector loom on my sons tdi. I did a VCDS scan and it showed a wiring fault on injector no 2. Car was basically in limp mode. Had a spare I knew was good and it cured it.
 
Chris Warren said:
Hi Dave, the problem in the end was the ‘dog bone’ stabiliser underneath that goes between the crossmember and the gearbox. The old one was shot. The engine would shake at idle, increase the revs it would smooth out. After changing it, the difference was incredible. A few weeks ago I changed the injector loom on my sons tdi. I did a VCDS scan and it showed a wiring fault on injector no 2. Car was basically in limp mode. Had a spare I knew was good and it cured it.
Click to expand...
Thanks for that Chris, I've just replaced my dogbone as well, but it hasn't made much difference at all, although the old one was kaput. Cheers, Dave
 
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