Engine Knocking and White Smoke

[Wooloowin]

Hi All,
I hope someone can point me in the right direction regarding my engine knocking problem.

Recently my number 2 injector failed. I replaced it with a new OEM unit and all related seals. The injector code was updated on the vehicle ECU by the local Eurocar mechanics. I also just completed a full 100k service and the vehicle was running perfectly.

I then thought it would be good to give the engine a good carbon cleanout. I purchased some Penrite Pro Series EGR and CAT cleaner liquid. It can be added to the fuel tank or directly via vacuum hose for a stronger clean. I wasn’t confident about which vacuum hose to use, but remembered seeing a number of similar cleaning products that were sprayed directly into the throttle body in short bursts.

I set up my air compressor with a spray cleaner gun and added the cleaning liquid to the container. In order to reach the throttle-body I added some clear hose to the spray nozzle. I started the motor and made short sprays. The engine coughed and choked and then a new mechanical engine knocking sound started. White smoke poured out the exhaust pipe together with a little initial liquid.

I was then shocked to find the atomized liquid from the spray gun had recondensed in the clear hose so the engine had been fed cleaning liquid directly (about 300ml). I thought the engine would settle down but it didn’t. The white smoke, severe spluttering and metallic knocking noise continued. I then shut everything down.

I used my Bluedriver scanner to read three new error codes. P067A (No. 4 glow plug), P2237 (Lamda Sensor), P0087 (Low Fuel Rail Pressure).
I was shocked to find part of the No. 4 glow plug had broken off. I removed the No. 4 Injector and glow plug and fed a stepped down hose from a powerful vacuum cleaner into both openings to try and remove any possible debris if any in the cylinder. I don’t think it collected any.
I then deep cleaned all four Lamda sensors (one was filthy and the other three weren’t too bad), checked all the related fuses and restored/recharged the battery to ensure full current (P0087). This cleared all the error codes from subsequent OBD2 scans.

The engine would start easily and was smooth for the first 30 seconds and then the metallic engine knocking would return together with billowing white smoke from the exhaust. The smooth start “seemed” like there wasn’t any mechanical damage. I checked the main Lamda sensor which was filthy again so cleaned it again. I repeated this 3-4 times but the same start up symptom process occurred. If the dirty Lamda sensor was the culprit surely the P2237 error code would have re-occurred. There are no error codes.

I am scratching my head and am down to 4 possible contributing causes
1. The dirty main Lamda sensor is causing the problem without error code and multiple runs/re-cleans are required before operating normally
2. Some other sensors or components are failing when the engine warms up (no error codes-which ones?)
3. There is mechanical damage in the cylinder head and or cylinder (Godforbid a rebuild)
4. The cat converter may now be clogged from the carbon cleaning (no error codes)

Any suggestions or directions to related information would be greatly appreciated.

Cheers

Wooloowin

[Wooloowin]

Just Updating problem diagnosis.

I have done both dry and wet compression tests (with fuel pump relays removed). Cylinder 4 is about 5 bar higher than the other 3 cylinders. The glow plug port on cylinder 4 also looks wet with diesel fuel. Getting a friend to turn over the engine revealed diesel spray out Cylinder 4 glow plug port. I swapped injectors in cylinders 3 and 4 and the original symptoms moved to cylinder 3. The culprit could therefore be a leaking injector. I have ordered a new one. I'll provide further updates on progress. (Note: The local VW dealership provides a diesel injector exchange price and reconditioned unit purchase option so on face value old injectors should be repairable. I enquired with some VW mechanics and Diesel Injector specialists that said the injectors couldn't be repaired and had to be replaced with new units. This is contradictory so I am making further enquires.)

The number 4 injector was working fine before I put through the EGR cleaning liquid. Perhaps it created a wave of carbon muck that jammed it open or something else.

Hopefully some of this problem diagnosis process will help others with similar symptoms.

W

[Wooloowin]

Looks like injector 4 started leaking after the un-vapourised 100% EGR cleaning liquid was added. The Lamda sensors also got drowned in the flushed carbon. The new injector cured the engine knocking and the car idled smoothly. Still a lot of white smoke at high revs. Half an hour of constant high rev driving eventually cleared dislodged contaminants along the exhaust path and the white smoke eventually disappeared. Just got to get the new injector 4 code correctly updated on the vehicle ECU by the local Eurocar specialist. Hopefully the vacumn cleaner step down hose suction through the injector and glow plug openings got rid of any potential broken glow plug pieces. Fingers crossed.