Sunday, 5 July 2015

VW Golf 1.6 TDI CR - CAY Engine Turbo Problem

My little MY2009 VW Golf Mk6 1.6 TDI is a little slow but it's economical and does me just fine.

However, a few months ago it started to misbehave. It suddenly wouldn't want to accelerate up hills, up to the point I was actually flashed by a taxis driver - embarrassing!

I lifted the bonnet (hood) and put a vacuum pump on the actuator (where the wastegate would normally be) thinking it was sticking but everything seemed to be OK mechanically.

VW Golf 1.6TDI - Engine Code CAY Garrett (Honeywell) VGT or VNT Turbo
You see, most modern turbocharged vehicles have variable vane boost control to alter the characteristics of the turbo, this is instead of directly controlling the boost pressure in the traditional way by bleeding off the wastegate back-pressure to control the boost. The net advantage of this is to provide a nice engine torque-curve (by controlling the aspect ratio of the turbo) coupled with greater fuel economy and lower emissions - a bit of a win-win.

However, these are mechanical systems and at the end of the day sometime or other they will break. The most common complaint is a build-up of carbon on the vane assembly itself causing it to stick or seize and gradually turn your car into a pig. Instructions how to free them can be found all over Youtube, an example of one such procedure can be found here using Sodium Hydroxide Foaming Oven Cleaner. Not in our case though, the vacuum pump showed that the vanes were moving, so they probably weren't stuck.

Connecting VCDS up revealed chaos in the ECU's DTC error table. Manufacturers try and make things easy for their service mechanics by getting the ECU to tell them what's wrong. However, if you have a mechanical fault, all that happens is the ECU starts telling you a whole host of errors (open collector fault, blah, blah) - In fact, the only error it didn't say was "Replace Whole Engine!".

I kept driving the car in it's "simulated full-race state of tune" for a month or so to convince myself what was going on. Googling around the various forums (carefully filtering out the BS that people seem to be good at saying), I was convinced that the Actuator Valve was not working and the Variable Vanes were randomly stuck in various positions.

I would not have been too bothered about this particular fault but the car was so laggy to get moving, it was damn-right dangerous to attempt to pull out of junctions. I'm sure other motorists must-have thought I was doing it deliberately because they saw me pull out in front of them, stop and then after several seconds suddenly accelerate away! Additionally, the fuel economy was absolutely terrible....

A quick Google search and trawl through eBay led me to CarPartsLink Ltd - Mike. The trick is to search for your engine code (CAY in my case) and include the words "turbo actuator". He was the cheapest on eBay and after a quick phone-call, he confirmed his part would fit and turned out to be a nice chap.
The old Turbo Actuator
A couple of days later it was in my hands and ready to fit. Fitting is quite straight-forward and can be done in a couple of hours with the turbo still attached to the engine.

Firstly un-clip the top engine cover, then remove the undertray of the engine because you will drop something! Secondly, remove the turbo inlet hose and the connector to the Turbo Actuator. You should now have a clear view of the turbo and Actuator.

Clear view of the Turbo Actuator and the bits you need to get at.
The three bolts that hold the actuator on need to be removed. They are T30 headed bolts with a little bit of quality-control paint on them.

Remove all Three Bolts.
I find that to help stop any bolt-head from rounding, place the tool into its hole and tap it in with a hammer.

Tapping Tools into place stops any heartache later!
On the underside of the actuator there are three 10mm nuts, remove them to loosen the bracket we've just removed. The purpose of this is to allow us to gain access to the actuator rod where it is connected to the actuator on the turbo.

You can just see the rod-actuator connected to the turbo's actuator.
The trickiest bit of the whole procedure is to disconnect the actuator rod. It's held in place by a circlip that needs to be removed. We can do this by modifying a pick so it looks like this:

A modified Pick to remove the Actuator Circlip.
There should be just enough room to get the pick into the gap and flick the circlip off. Usually, it's about this time you realise you should have removed the undertray! All being well, assembly is just the reversal of removal. Once everything's in place, you can marvel at your hardwork...

Your work from this angle...

And your work from this angle!
Testing can be a little fraut and frustrating because you have to remember that while this fault was going on, the ECU has been attempting to bring the boost pressure back to normal. This will mean the car will seem very flat to drive and not wanting to rev at all. You should attempt to try a few gentle standing starts and back to stop again. Additionally, gently accelerating in second gear from 1,000 RPM to 3,000 RPM will slowly teach the ECU the correct parameters.

Good luck and I hope this helps somebody. Andy