Friday, 3 April 2015

1.6 Tdci Turbo Failure? Here's The Real Cause

Ford, Peugeot, Mini, Volvo 1.6 Tdci Turbo Fault

In this article we take a look at the main root cause of turbo failure on the PSA 1.6 Tdci engine. This engine is fitted to a wide variety of manufactures vehicles with Ford, Peugeot, Mini, Volvo and Suzuki to name but a few. A list of just a few of the common models affected are:

  • Ford Focus 1.6 Tdci
  • Peugeot 307 1.6 Hdi
  • Mini Cooper D 1.6 9HX engine
  • Volvo S80 1.6D DRIVe

Whilst turbo failure is a common occurrence on this engine, once properly repaired a new turbo should last many thousands of miles.

The cause of turbo failure on the 1.6 Tdci engine starts, not with the turbo but instead with carbon build up and the injector seals. Once the carbon builds up in the engine oil it will cause the gauze filter in the turbo oil feed banjo bolt behind the DPF/Exhaust to block and starve the turbocharger of oil. 

To measure the oil pressure directly at the turbo I made a special adaptor for our oil pressure test kit. Your kit may vary so making the adaptor could be different for everyone. Here is the how I connected the test kit to the turbo: 

How to measure oil pressure at the turbo
Oil Pressure Test Connected To Turbo
Next I measured to oil pressure here is the result:

Oil pressure at the turbo with the gauze still fitted
Result Of First Oil Pressure Test
The engine oil pressure at the turbo whilst the engine was at idle was around 0.8 Bar or 12 Psi, way below the recommended 2.3 Bar minimum. It was clear this turbo had failed due to oil starvation.

Because the 1.6 Tdci engine leaves the factory with a gauze filter in the oil feed pipe bolt the next step was to remove the bolt, remove the gauze, refit the bolt and measure the oil pressure for a second time. This step also confirms that oil pump and oil pick-up are in good working order. Here is the result from the second oil pressure test.

Turbo oil pressure test with gauze removed
Result Of Second Oil Pressure Test
The resulting oil pressure with the gauze filter removed was 3.4 Bar which is more than acceptable for the PSA 1.6 Tdci engine.

For reference here is a image of the gauze, in this case the oil feed pipe was replace by another garage before. However they failed to take the correct steps and remove the gauze filter after 30 miles, they also failed to replace the injector sleeve oil seals and clean other traces of carbon from the engine, this resulted in the new turbo failing within 2 weeks:

Turbo gauze filter
Turbo Oil Feed Pipe Gauze Filter
Next we replaced the turbo and followed the instructions that came with the turbo. The main points of which I have listed below:

  • Oil feed pipe and banjo bolts replaced.
  • Oil sump removed and cleaned.
  • Oil pick up / strainer replaced.
  • Oil filter housing / oil cooler removed and cleaned.
  • Charge air cooler / intercooler removed and cleaned.
  • Exhaust checked for blockages.
  • DPF cleaned.
  • Brake vacuum pump removed and cleaned.
  • New oil filter fitted.
  • Oil return pipe from turbo removed and cleaned.
All the above points are critical actions you must take to ensure that a new turbo will last for thousands of miles. However I missed one point and it is the most important part as this what will have likely caused the carbon build up in the oil that ruined your turbo in the first place, and that is the injector oil seals.

The number one cause of turbo failure on the 1.6 Tdci engine is the build up of carbon around the injectors and the eventual failure of the injector oil seals. This is due to the injector sealing copper washer failing, carbon then builds up in the injector sleeve, this then rots the injector sleeve oil seal, carbon then gets into the engine oil and will eventually cause turbo failure.

Here is an image of the build up of carbon around number 4 injector in this case:

Build up of carbon on injector
Carbon Build Up Around Injector
Once the injector is removed it becomes clear how the carbon builds up in the injector sleeve, here it is compared to injector number 3:

Injector carbon build up comparison
Comparing Injector Carbon Build Up
We then covered the holes and cleaned the carbon away to expose the injector sleeve oil seals. Once this was complete the damage to the oil seals was clear. For reference here is an image looking straight into the injector sleeve:

Injector Sleeve Oil Seal Faiulty
Injector Sleeve Oil Seal Failed
Now if we compare this to the seal on injector sleeve number 3, it is obvious that the seal on the forth cylinder was damaged sufficiently enough to allow carbon into the oil system:

Injector Sleeve Oil Seal Good Condition
Injector Sleeve Oil Seal In Good Condition

With the seal replaced, the injector sleeves and injectors cleaned, injector copper washers replaced and the injectors refitted all that was left was to put fresh oil in the engine. 

The final step and this is also critical was to drive the vehicle 30 miles and then strip and remove the gauze filter from the banjo bolt on the feed pipe to the turbo. The oil and filter was then replaced again and the vehicle road tested a further 50 miles. 

It is recommended that after the turbo is replaced and the above procedure is followed to correct the original cause of turbo failure, the oil and filter should be replaced every 3000 miles.

I hope this helps anyone that has experienced turbo failure on the 1.6 Tdci engine.

Monday, 30 March 2015

AdBlue Warning Light On (Fixed)

Volvo FL AdBlue Fault

A Volvo truck was presented to our workshop today, the driver had reported a fault that the instrument cluster was showing a warning for AdBlue system failure. 

Naturally the first action to take was to carry out a diagnostic code read. However when we attempted to code read the AdBlue control module (ECU) it was found to be not communicating.

Instead carrying out a fault code read of the engine control unit was found to be useful, here are the results:
  • MID(128):Injection ECU, PSID:229, FMI (9):Data update frequency
  • Connection problem with the UDS (AdBlue pump module) ECU on the SAE J1939 CAN bus data line.
It became apparent that the AdBlue system was not accessible due to a CAN bus fault. 

The next step was to monitor the CAN network at the AdBlue ECU. As we explained in our previous CAN fault finding article, we first test the CAN network with the wiring block disconnected from the AdBlue ECU. The oscilloscope was setup as follows:

  • Channel A / 1 - 5vDC
  • Channel B / 2 - 5vDC
  • Timing - 50 nano seconds

Here is the waveform as viewed on the oscilloscope:

Good AdBlue CAN Signal
Good CAN Signal AdBlue System

As you can tell with the ECU disconnected the CAN network behaves as expected (equal and opposite traces between the CAN High and CAN Low). Next we reconnect the wire to the ECU and continue to monitor the CAN signal with the oscilloscope, again here are the results:

Bad AdBlue CAN Signal
Bad CAN Signal AdBlue System

It is clear that with the AdBlue ECU connected there is a definite fault with the CAN signal. Most notably on the red CAN Low line. This suggests that the fault lies within the ECU and not the wiring.

Next we removed the ECU from the AdBlue module and proceeded to open the ECU to see if there was any visible corrosion or burnt components. 

We found corrosion and a burnt component on the circuit board, here is an image of the burnt component: 

Blown ECU Component
Blown Component Between Pins

We proceeded to order a new AdBlue pump and ECU module, once received it was fitted the fault codes cleared and the the vehicle road tested. All was good the fault was fixed and the vehicle returned to the customer.

Hopefully this article helps you to diagnose CAN network faults and determine if the fault is in the wiring or ECU.

Why not leave a comment if you have had a similar experience.

Monday, 23 March 2015

CAN Error Testing And Repair

A Quick Look At CAN Network Testing

A vehicle arrived at our workshop today on the back of the wrecker. The fault reported was non-start and also the instrument cluster was showing a warning that the vehicle was not recognising that the gearbox was in neutral.

Although the tests and fault finding steps in this post are the same for most vehicle CAN networks, the vehicle we were presented with was an 2008 Iveco with a ZF AS-Tronic EcoLite gearbox.

The first course of action was to carry out a diagnostic code read on the transmission system, here are the results:

  • Fault Code - 806 - Clutch Actuator
  • Fault Code - 830 - Clutch Position
  • Fault Code - 833 - Clutch Position Open
  • Fault Code - 834 - Clutch Position Closed
  • Fault Code - 900 - Terminal 30
  • Fault Code - 907 - Relay Circuit 1
  • Fault Code - 909 - Relay Circuit 2
  • Fault Code - 865 - Gear Select
  • Fault Code - 896 - CAN Error Message
  • Fault Code - 918 - Clutch Valve 2 Closed
This, coupled with the fact that all power supplies and earths were present and correct, also that other ECUs reported communication errors with the transmission ECU, meant that testing of the CAN network at the gearbox was the next step.

The CAN wires are normally easy to identify at the ECU harness as they are usually a twisted pair, however if you have a wiring diagram for the vehicle available it will help tremendously.

I monitored the CAN network using a PicoScope however any 2 channel oscilloscope will do the job and should be setup as follows.

  • Channel 1 or A - CAN High
  • Channel 2 or B - CAN Low
  • 10ms rate
  • Channel 1 and 2 or A and B - DC 5v

A quick and easy way to tell if the CAN signals and wiring to the ECU are in working order is to disconnect the plug from the ECU and measure the CAN wires with the oscilloscope. In this case the results are in the image below.

Good CAN Network Waveform
Good CAN Waveform
As you can tell the CAN waveform is as you would expect. Each wave on the blue CAN High trace has an equal and opposite wave on the red CAN Low trace. This tells me that the CAN network is normal and working correctly with the transmission ECU disconnected. 

The next test is to reconnect the plug to the transmission ECU and monitor the CAN. Here is the result from the oscilloscope.

Bad CAN Network Waveform
Bad CAN Waveform
In the above image it is clear that once the ECU has been connected it introduces a definite fault and this is most notable on the red CAN Low wire. 

This led me to suspect the transmission ECU was fault and the next step would be to remove the ECU and send it for testing and repair.

Once we received the ECU from the repairers, we reconnected it to the vehicle and was able to confirm that the fault had been repaired by clearing the codes and checking that the vehicle started, which it now does!! 

I hope you found this post informative and now have a basic understanding of CAN fault finding. 

If you like these types of articles and would like to see more please leave a comment below.