Volkswagen Touran 1.6TDI CR Wobbly Idle / Hunting when engine is cold

[TommyT]

Hi again, so as the title really. My 2011 1.6 CAY engine VW touran has developed a cold start issue which makes it hunt and wobble. It makes a noticeable claatter noise when this is happening as well which isnt good!  It only happens when the car is stone cold and after about 5 minutes of driving its done and silent. The car still drives normally with this going on and the issue is only noticeable when the car is at idle.

With the help of @Mirez I have uploaded a little video to show what the problem (thanks)

I have VCDS and there are no error codes showing so not 100% sure what's going on. I believe this is the same engine as fitted to the Golf and Passat, the CAY engine which is known to sometimes have injector issues. So my question is has anyone first hand experience of the injectors when they fail?

Address 01: Engine (J623-CAYC)       Labels: 03L-906-023-CAY.clb
   Part No SW: 03L 906 023 H    HW: 03L 906 023 A
   Component: 1,6l R4 CR td H23 9970 
   Revision: --H23---    Serial number: 00000000000000
   Coding: 00254014032500080000
   Shop #: WSC 01357 011 00200
   ASAM Dataset: EV_ECM16TDI02103L906023H 003010
   ROD: EV_ECM16TDI02103L906023A.rod
   VCID: 2B55315B425B0E1A25-807E

No fault code found.
Readiness: 0000 0000

[Mirez]

Hey Tom, so as we discussed its likely to be one or more injectors on the way out, these engines seem to be prone to them unfotunately. and there is little infomation on the net about testing the injectors on the 1.6 TDI that I have found. It may be hit and miss diagnosing this but I can give you some pointers from what I've learnt. It's worth noting that since the 2.0 also uses the same injectors (03L130277b/s) and they don't seem to suffer so much I personally think the issue is partly software related. The other thing is that 2013 on cars with the S suffix injectors also dont seem to suffer so much.

From what you've posted so far, your engine software is "Component: 1,6l R4 CR td H23 9970".is an early firmware revision, I'm suprised that a 2011 in on 9970 tbh as 9971 has been seen on some late 2010 cars so is yours just a 2011 (11 plate) or a 61? Anyway 9971 software definately improves injector on cold starts. I believe the latest firmware is 9975 which is the emission recall software but right not VW havn't started rolling that out yet. I would speak to your dealer about maybe getting that updated, hopefully you can get them to do it for free if you are lucky.

As for diagnosing them, you want to use VCDS in the advanced measuring blocks section to log "Injector deviation" on all 4 cylinders. Again, not a lot out there on how to diagnose but I would suggest logging them for 30 seconds with the engine WARM. Post the results back when you can

[TommyT]

Thanks @Mirez, I did as you said. What do you make of these figures?

[Mirez]

That looks like the right data, Can you average the columns in excel and post back?

[TommyT]

Hows this?
[attachimg=1]

[Mirez]

Good! Now obviously we want the deviation to be as close to zero as possible, the idea of averaging the columns is because there will naturally be some injector deviation. Since the ECU will respond to positive deviation by reducing the fuel and negative deviation by increasing it, a faulty injector should see a lot of fluctuating figures. By averaging out the values, we get to see the ones which are really screwed, by those readings Cylinder 1 is your problem and 3 isn't far behind.

[TommyT]

Would you replace just the one or both then? I don't suppose there is any how to's out there for changing them? Any tips or pitfalls I should know about?

[insanitybeard]

I'm not sure if it's a required procedure with the VW injectors but sometimes it's necessary to enter injector correction values when renewing commonrail diesel injectors (some of the reasons for that are mentioned in the links in this thread), I've not used VCDS (which if it is required you would need to use to enter them) so it needs somebody else who has to advise you here. Sometimes you need a special socket to unscrew the injectors from the cylinder head but again I've no direct experience of replacing VW TDCI injectors, and it's also recommended practice to renew the high pressure fuel pipe which connects the injector to the fuel rail. Parts diagram here.

[Mirez]

Personally, and given the cost, I would replace just the one injector and then see how/if the symptoms improve. Since you are looking at 1 and 3 this makes sence because they are grouped 1+2 and 3+4 so you are only disturbing one set initially.

I noted you already have VCDS but as Paul said you'll need the full version to code injectors but its an easy process and I'm happy to guide you through.

[TommyT]

So I changed injector 1 last night and this morning it is much smoother but still has a little clunk from time to time so might change number 3 tomorrow. also found a setting in the adaptions menu to adjust the idle so added 70rpms to that which made it really smooth. I took some pics so happy to wite up a howto if that would be usueful the others?
Thanks for all the help people!

[Mirez]

How-to's are always very welcome mate! Thanks

Glad its semi-sorted, how easy were they to change?