Few symptoms on sick Golf

5 July 2013  

By Frank Massey

Golfs fitted with the ‘pumpe duce’ or PD engines are hardly uncommon in these parts and a recent marketing campaign on the internet has seen a number of new customers with late-model German cars come to our door. If we wanted this particular customer to keep coming to us, we would have to quickly find out what was wrong with his vehicle.

Remember that cost is the true value for every job, its value is often obscured by many things. For example, time, tools, parts, training, and even things like environmental costs of running your business.

Previous attention from the customer had revealed no DTC errors – something that we confirmed ourselves. While this doesn’t disqualify the possibility of a sensor or circuit value error, it does by implication demand a different approach, which is likely to make the job a bit more expensive.

A new EGR valve had been fitted however, the symptoms of poor starting from cold and stalling were often present.

There could be any amount of reasons for this, so I decided to monitor the crank and cam sensors (triggering) via the serial port. To enable a stable environment power support was provided to both Autologic and the vehicle battery using Fronius. Despite this communication with the powertrain control module (PCM) dropped out every time the vehicle was cranked.

There was no option but to access the PCM and conduct further ‘pin out’ testing using my Picoscope.

What happened next was both interesting as well as surprising, having accessed the crank and cam sensor outputs it identified a clear but intermittent partial output failure. This was made even more curious by the fact that no misfire or unevenness of the engine was present.

Due to the mathematical predictability of the error it could not be due to a wiring or sensor failure, such is the advantage of oscilloscope analysis. At this stage I was pleased to have isolated the fault but had to go to the customer with the really bad news that it was going to have to be a gearbox-out job to replace the phonic wheel. This rather fragile magnetic disc requires precise positioning on the crankshaft using a special locking and fitting tool.

With the gearbox out, further assessment confirmed the need for a new flywheel and clutch. With all the chickens in the hut an accurate final cost could be confirmed. The original dual mass flywheel and clutch were replaced with an LuK set. Following this, the gear box was steam cleaned and the concentric release bearing primed prior to reassembly.

The conclusion was a very satisfying professional job, with a satisfied customer. As for the car, it was being sold the very next day! Such was the confidence and agreement between the repairer and owner. I hope this tale highlights the true meaning of cost, and the need for training and investment delivered by craftsmen.