1.6 TDI VDO Injector failure root cause analysis

[ransomz0]

This is very interesting information. I was not aware it was possible to repalce parts of the injector. Would anyone be prepared to post a How To guide to show how to replace the electrical parts, I'd be happy to chip in as required?

Great thread ....

[BenT]

Oh, it really couldn't be more simple; this is the beasty we know and love:



The large nut just to the right of the black plastic cap on the piezo actuator in the picture just unscrews to yield this:



Then you'd just screw a new one on. Here's a link to the alibaba ones:

https://www.google.com/url?q=https://s. ... r6KyI7w5xY

I'm not promoting this site in any way - I've never used it and it may of course be scamful. I'm thinking of buying one and fitting it to my failed injector (which is presumably otherwise fine) so I've got a cheap spare. There's the issue of coding it, but as Ricky302 said this might not be a problem. There's also a subroutine in VCDS/VAGcom to help with calibration, if using the value stamped on the injector doesn't work. Here's a link to a video on it:

https://www.youtube.com/watch?v=RmbN936pXQ8

The second half's the most relevant.

I'd be a little concerned about snapping the injector retaining bracket if trying to swap the actuator by the roadside without removing the injector first, they're very tight. The re-tightening torque of the new actuator on the old injector possibly plays a part in the firing delay after receiving a signal from the ECU, which would need to be accounted for.

It's almost certainly not the done thing, but I'd like to know if it's possible/safe to prevent the engine from going into full limp mode on injector failure. The offending cylinder would need to be shut down, but if the engine ran with boost pressure on three cylinders it would at least be less immediately dangerous. Just a thought.

If we could remove the safety problem and use Ricky302's method as a cheap fix, then injector failure ceases to be a problem if you're confident enough to undo one nut and swap the actuator.

[ransomz0]

Ricky302 which supplier did you buy from on Aliexpress?

I might buy one as a spare.

[Engineer Bob]

The possibility of changing only the piezo actuator maybe a great way forward to reduce the cost of these failures. I have a number of concerns, however, which relate to the reliability of the manufacturer's process and whether or not the programming would have to be changed due to the tolerances within the actuator build. I am not very confident to carry out any re-programming, having never undertaken this before and not having access to a VCDS. I note that the Chinese supplier of the actuators (using the link provided by BenT) does not provide any warranty and appears not to supply to my address. Other suppliers shown on Aliexpress seem to all be located in China, have long delivery times and are more expensive. I don't wish to sound so negative, I am only trying to persuade myself that this may be the way to go in the future!

I now have my Caddy back, The cost of replacement injectors (four) since November 21 has been over £3,100! I also have the two injectors that were recently replaced, one that had failed, the other changed in an attempt to prevent any near future failure. I will be examining the piezo actuator of the failed one in the near future and will post my findings. incidentally the resistance reading across the terminals of the failed injector was 1.8 ohms whereas the 'good one' had a resistance reading of 198k ohms.

The one question that keeps niggling me is why don't VW (Siemens/Continental) provide the actuators as a separate item, unless the reason is purely to generate maximum profits from us poor suckers!

[C Chis]

Here’s a thought (a daft one most likely)

As you can remove the electric actuator would it be possible to do the same with the less problematic 2.0L injectors and fit the 2.0L actuator to the 1.6L injector?


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[BenT]

Not daft at all! In fact, the 2.0 injectors are so cheap (relatively) it would be much easier just to sway the whole injectors across. The biggest problem I can see (other than possibly a new leak-off arrangement) is that these injectors might require a different trigger waveform and might operate at a different voltage to the VDO injectors. I really don't know. As EngineerBob's said, I don't know how much more reliable the Bosch Piezo injectors are. But, they are much cheaper to buy second hand, which might point to them being in less demand...

[Ricky302]

Ricky302 which supplier did you buy from on Aliexpress?

I might buy one as a spare.

Sorry for the late reply, I didn't buy them from Aliexpress, I bought a whole reconditioned injector from Ebay but the problem was I couldn't remove the broken one, it was completely stuck, so it was only after a bit of reading and finding out it was the electrical part that failed on these injectors that I decided I didn't have anything to lose by just replacing that part.

[Sebspring]

Brilliant thread. Genuinely enjoyed reading it. Thanks for taking the time and sharing your findings

Like all of you.. I'm so 'over' this nonsense now.

I've had another go pop. No warning this time. It had a momentary 'cough'about 10 seconds prior.. and my heart sank.. I knew exactly what was coming. 70mph Lane 3 and it just died thankfully I managed to coast with the speed to a slip road just ahead without causing to much drama for those in lane 1&2.

I can't afford to fork out like I did last time to get yet another injector replaced so I have no option but to swap it out myself.

2 questions for you knowledgeable chaps..

1. I read a couple of pages back.. someone recommended TT Automotive to supply replacement injectors. Do I HAVE to be a trade customer to get my hands on 1 or 2 injectors? (If I'm changing 1 i might as well take out the only other remaining original) or will they sell them to me as an unknown individual?
How much did they charge?

2.Anyone recommend or know anyone in the Surrey/Hampshire area that would code the replacement(s) for a reasonable price,
From what I've read I can just fit them and get back on the road until I get them coded.

I'd have a go at doing it myself.. but I don't have a laptop (presuming I can do this with copy of VCDS off the net somewhere?

[ransomz0]

You can code them with obdeleven.

[DW2207]

Agree with the above statement, plus its handle little device to keep in the van for those just in case moments.

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[Stumpmagnet]

i assume the reconditioned items may have these new solenoids fitted? would be worth buying a couple to try then code back in with vcds or obd11

[Jmpl]

Our caddy goes trough another round of replacement of injectors. Some were eBay bought from German recon business some from Eurocarparts. Last one cylinder 1 failed data in comparison to others

Resistance 11ohm
Capacity less than 1000uF
Voltage disturbance or almost not visible on labscope at certain moments.
0MJ

The German recons
Resistance 199k Ohm
Capacity around 5500uF
Voltage wave visible going in 3 highs per cycle.
39-40k MJ

Eurocarparts
Resistance 200.1k Ohm
Capacity around 6000uF
Voltage wave same
41-42k MJ

Replaced all 4 with German recon - Now at some point ecu said number 4 faulty so replaced 4 with the Eurocarparts one. Few days later ecu turned out number one faulty so for the check what will happen did put the one from no4 (German) and it works however data are on this slightly different
Resistance 199k Ohm
Capacity 2600uF ???
Voltage wave similar same as 39k MJ.


Let’s see what will happen…
TBC

[BenT]

Thanks for the info! What test did you carry out? I'm not familiar with the voltage cycling. I'm not surprised about the capacitance falling after failure though, when the piezo stack breaks down I'd guess this is akin to dielectric breakdown in a capacitor..

Still the perennial question though - do the crystal sheets break down over time, leading to shorting, or is there some sort of voltage spike going on which causes the material to crack? Not that we can do anything about it mind you.

[windsweptofwyke]

Hi, I'm a new to this site, and not sure I understand all of the above but I have had multiple breakdowns in my 1.6 litre caddy every time it is fuel injectors failing. And I have only done 9500 miles.

So here goes
31/1/15 Car leased on motability scheme and fitted with hoist for my mobility scooter. (not cheap)
9/1/17 NOx recall done at 3478 miles
Car then bought from motability
17/5/19 injector 3 fails 5511 miles - going up a hill
7/12/19 injector 1 fails 6184 miles - going up a hill
22/10/22 injector 3 fails 8248 miles (replaced roadside by RAC)
3/10/22 injector 1 fails 9447 miles all tested and 1 failed, 2 in poor condition and 1 is fine (which is ok is not certain as yet ... awaiting the report) - going up a hill
12/10/23 only done 20 miles if that, and something still isn't right. The only injector which was tested as good had now also failed, meaning all 4 replaced and the RAC VW original part lasted less than a year. Car currently being repaired, bill not finalised.

So I have spent £3122 and still waiting for the last bill. So that will be about £3700 in total. That is money I'm not spending on things that improve my pain and disability.
Worst of all I don't feel safe to go anywhere. And I'm about to move house so can't afford to take a new lease or PCP agreement or put any more money into a car.

I live in a hilly area of the SW of England, it is impossible to avoid hills here, I even live up a steep road.

The breakdown guy on the last breakdown said it is common fault for caddy 1.6 and in his experience is always either injector 1 or 3 that fails. He has known people replace all 4 and then it goes again.

VW have been spectacularly unhelpful. I am writing to head office in desperation.
I am utterly reliant on that vehicle to be able to go literally anywhere.

If anyone can explain in fairly basic language why it keeps happening, or more importantly what to do to stop it happening again I'd be very, very grateful. But it looks like that is the million dollar question to which there are no solutions. Is that right?

[BenT]

So sorry to hear of your problems - what a nightmare. Have you considered swapping your Caddy for an alternative?

I'd guess there one or two boffins at Siemens VDO who've carried out thorough investigations and know what the problem is, but they'd probably keep it a closely guarded secret anyway. And there's a limit to what a random nutter with a hacksaw (i.e. me!) can achieve... all I could see is that the piezo stacks had shorted out in more or less exactly the same place on the two which I took apart. Dielectric breakdown I suppose. But whether the cause was mechanical or electrical I have no idea. It may not even be the stack to blame. Perhaps a random metal fragment could jam up the mechanism further down in the injector preventing the stack from being able to expand, causing it to crack?

I sort of feel as though the piezo stacks just naturally deteriorate with use - they're brittle ceramics after all, and it makes sense that they might just gradually crumble over millions of expansion and contraction cycles. I think the VW emissions fix utilised multiple injection cycles for each power stroke when the engine's cold, which adds to the wear. DPF regeneration also requests more injection cycles per stroke. So, perhaps engines which cover a lot of cold engine miles and/or do a lot of DPF regenerations and/or have had the emissions fix applied might fail sooner just because the injectors are working a lot harder. I'm happy to be corrected!

The first one to fail for me was the #2 injector. In the West Country, going up a slight incline at 148 k miles. My #3 injector had the decency to let me know in advance that it was poorly a couple of weeks ago, since the van would only run on 3 cylinders for 5 seconds or so from cold start up! So I've replaced the #3 and #4 injectors together to save hassle.

This isn't just a VW problem - a friend at work has a newish Qashqai 1.5 dCi that's just done the same thing - another Siemens Piezo job...

My "solution" has been to always carry at least one spare injector with me, along with a triple square bit, ratchet spanner, 17 mm spanner, lots of kitchen roll, cable ties (for yanking the injectors up and out), WD40 and a small screwdriver for the electrical connection. And a stretch bolt for the injector clamp. It's actually quite an easy and quick job. If you're lucky enough to be able-bodied... Still a pain not knowing when you're going to be left stranded though.