A2 Tdi 2003. Loss of power when cold ABS and Yellow Triangle on! All clears once engine is warm and drives normal. Very confused, please help.

I’ve dealt with misfiring TDIs loads of times.

@MoMo’s experience clearly suggests that injectors do fail. Of course they do; it’s a mechanical system. However, I have never cured a misfire by changing an injector. Every single time that this fault has been placed beneath my nose, a replacement injector wiring loom has solved the problem. This is, I believe, indicative of where the problem most likely lies.

All the best,

Tom
 
Thanks @timmus for your input.
I do hope it is only the wiring loom. Is it worth trying to clean the connector?
How/Wherever that is? See if that improves things, at all?
 
I have found that cleaning the single external connector and the three internal connectors does improve matters …but only ever temporarily. You may get a few thousand miles before symptoms start again.
The injector wiring loom has a hard life. The major effort is accessing the thing, meaning it makes most sense to replace the loom, particularly if you’re paying someone else to do the work.

Cheers,

Tom
 
OK thanks so much again. . I just thought I may try cleaning what I can get to myself, whilst I'm trying to find someone in my area to do the wiring loom.

Is there any pics or guides how to clean the connector, this without taking the cover off?

I am now reading posts on intercoolers, hmm.. that seems even more complicated and labour time a few hours!
 
Unfortunately the only part of the loom you can access is the knurled wiring connector on the side of the head, the rest of the loom is internal. That is why by the time you can see it it is better to just replace it.
 
To add my 2 cents worth having had a similar intermittent problem to you, I agree with the above comments that it does sound likely that the cause is the injector loom but I personally don't believe the injector loom goes bad.

Its also not so much cleaning that is the solution (although you would obviously do this as a matter of course) as I believe that the problem is simply that the three spade connectors (one onto each of the three injectors beneath the cam/rocker cover) just wear loose over time through constant vibration and in my own experience this was indeed the case.

When I gained access and inspected them, the connector onto cylinder 2 (which was the related fault code on mine) was very loose indeed and not making a continuous connection, hence the intermittent fault and the connectors on the other 2 cylinders were a little on the loose side too, so the cure was to simply remove the connectors one by one, tighten them, then refit again ensuring a nice tight fit and which for me was a 100% fix to the problem and which hasn't returned since, maybe two years or so later.

I also agree with the above though in that it is the same amount of work to do the fix that I did or replace the injector loom itself as the cam cover has to be removed to access the injector connections, so if you aren't doing the job yourself and are paying a garage labour to do so, it MAY be a good idea to spend the extra £100 or so (the cost of the injector loom) and fit a new one. Not what I would do but your decision to make 👍
 
@audifan @A2Z
Thanks again for your advice. I think I must have mis understood a past post on the wiring loom. Cleaning the connector was possibly something else, that I could access myself;)
I have already purchased the wiring loom, so do intend to change it if it needs it. I just need to find someone available and familiar with it to do it now, and check see if the connector loose, damaged. I will show them all your advice, when I find someone.
Is there a link to showing how to fit a loom?
 
Sunflower said:
@audifan @A2Z
Thanks again for your advice. I think I must have mis understood a past post on the wiring loom. Cleaning the connector was possibly something else, that I could access myself;)
I have already purchased the wiring loom, so do intend to change it if it needs it. I just need to find someone available and familiar with it to do it now, and check see if the connector loose, damaged. I will show them all your advice, when I find someone.
Is there a link to showing how to fit a loom?
Click to expand...
For my tuppence-worth - if the rocker cover is coming off to access the loom, given how much of a job this is (and likely need to fit both a replacement cover and new gasket afterwards owing to the propensity of the old rocker to warp), it makes sense to get the injectors removed and sent away for a pre-emptive clean and service as well as fitting the new loom. That should give another 100k at least. Made a huge difference on my project car (then >290,000 miles) in terms of smoothness of running and fuel economy.
 
@Robin_Cox
Thank you for your input. I would love to be able to do what you suggest, it makes sense but I really need the car at moment, on a budget, plus not sure how the garage would be me leaving the car. It kooks like I can't get it in anywhere for at least another few weeks with a garage. Will have to try muddle along as it is....Is it better with a garage or maybe an auto electrician?
 
Sunflower said:
@Robin_Cox
Thank you for your input. I would love to be able to do what you suggest, it makes sense but I really need the car at moment, on a budget, plus not sure how the garage would be me leaving the car. It kooks like I can't get it in anywhere for at least another few weeks with a garage. Will have to try muddle along as it is....Is it better with a garage or maybe an auto electrician?
Click to expand...
I have no idea how to answer that question - the only answer that I can give is that since accessing the injector loom means that you need to take the rocker cover off - and then putting it back on (which are both a pain of a job) then if you're going to do that, servicing the injectors as part of the same job is a no-brainer.

Probably a mechanic rather than an auto electrician's job owing to the engine dismantling needed even though the loom is electrical.
 
@Robin_Cox
Thanks again, yes totally understand what you are saying. Are you able to tell the state of the injectors by removing and looking at them, see how bad they are? What is the cost of servicing the injectors? It's difficult at the moment to be without a car, and findi a new mechanic who familiar with A2's.
 
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