VW Golf injector woes

[Tim M]

I have a 2007 1.9 TDI Golf. A month ago it wasn't sounding very happy so it went into the garage (independent VW specialist) where it was diagnosed as being a faulty injector (number 4). Injector was changed. When it was collected we were told they also had to change the injector harness. Anyway, it all ran fine.

A month later, same problem again. Engine is only running on three cylinders, sounds and runs just as it did before. Had the AA out and he confirmed its an injector fault (AA recovered it, I caught the train, it turned up at the house covered in mud with the rear light cluster smashed so god knows what happened there ).

I suspect the first time around they changed the injector and it still didn't work, hence they changed the harness. But on that basis it's unlikely to be the harness again as its had a new one.

Does anyone else have any ideas? I'm going to whip the rocker cover off tomorrow and try and establish which injector is playing up. I have a funny feeling its going to be number four again. Going to swap that over with another and see if its the injector or the power supply to the injector. Does the injector feed straight back to the ECU? Really hope its not an electrical issue as this is going to be tricky!

[boristhebold]

Ive had issues in the past with petrol vw golf gti and audi s3, injector issue is common, however sounds like they changed an injector coil and the wiring harness, so my question would be was and is it an injector coil or one of the actual injectors ? Is it similar with diesels.

Ifmit were me and if its a similar setup to petrol then perhaps swop the coils around, clear the fault code and re test and see if fault moves to another cylinder, that might indicate a faulty coil, if it doesnt move then perhaps the actual injector is at fault.

Any mecanics out there who can comment on above as im no mecanic.

And i dont have much faith in main dealers, try a good known mecanic with the right equipement.

[ribraff]

Had exactly the same thing on my other halves 2005 Golf, machine showed lack of efficiency on two injectors,replaced them but that didn't work, I replaced the internal loom, that didn't work either, took the turbo apart and cleaned it as its the VVT version which is prone to clogging, no joy.
Turned out to be the ECU in the end, it's sited just below the windscreen under the bonnet, it had water dripping on it which corroded the internals and then started throwing random fault codes.
Easy enough to get out and see if there is any corrosion on your PCB.

[tom_20000]

IF you can grab a VAGCOM cable and VCDS, can run your own fault tests then very easily. Ross-Tech do a great kit. The guys on the VAG forums are usually really helpful

[Erin]

Seems a bit odd that it worked fine for a while after replacing the injector and loom. Perhaps a poor connection at the ECU end of the loom which made enough contact for a while when the new loom was plugged in but is now failing again.

As suggested get any codes pulled by someone with VAGCom/VCDS or your nearest 'helpful' dealer then do a search on line with any fault codes found.

[Tim M]

Thanks for the suggestions. Someone suggested I replace all the injector seals. For £25 its worth a shot. Seals hopefully arriving Tuesday. After that it's back to the garage....

[Ian M]

If it's going back to the garage why mess with it? They will only blame your handiwork for whatever issues they find.

[diver 1]

I'm no expert as I never owned one of the affected cars but I'm aware the VAG 2.0TDI engines from circa 2005-2008 are to be avoided if possible.
The 1.9 TDI's were good and the later 2.0TDI's with common rail are good (I've owned both) but I've been warned by many experienced and knowledgeable mechanics to avoid the interim engines. A google search I'm sure will reveal a lot more. Its normally oil pump failure which in turns screws the engine due to lack of oil getting to turbo, bearings, etc.

[Tim M]

Just as a follow up, turned out to be a combination of a sticking valve and a dodgy fuel filter.