HELP - Bluey/white smoke - 1.9 CDTI 150

[DieselWig]

I've just replied to Micky86's latest post - again, sounds like DPF regen - Signum's have these DPFs too. If the smoke is coming out from the front of the car, it may also be a sign of a split flexi-section of the exhaust or split DPF hose to the differential pressure sensor.
As soon as a regen begins (and it won't when you first start the car), more fuel gets delivered in order to heat up the exhaust gases to burn the soot in the DPF, but if the DPF is seriously blocked it can result in back pressure splitting the sensor hoses and exhaust gases can escape from any leaks in the exhaust upstream of the DPF.
If you have the MPG readout, can you see this figure decrease when it begins to smoke? This would be another sign of the regen starting.

[Teapot]

My signum occassionally emits blue smoke for the first minute or so of a DFP regeneration.

If is is DPF regen as suspected, the blue smoke is caused by the post-injected fuel. At first the pre-cat is not hot enough (about 200 degress C) to fully catalyse the unburned post-injected fuel. As the fuel continues to be catalysed, the pre-cat temperature will soon reach approximately 600 deg C, thus the pre-cat is working effectively and no more smoke will be seen.

If blue smoke continues after approximately 1 minute, then either the engine is not hot enough or the pre-cat is faulty.

The way to tell if a regen is in progress is to look at the instantaneous mpg reading on the BC whilst idling. During regen it will read 0.6-0.9 gal/h. In normal operation it will be 0.1-0.2 gal/h.

[d_ghedia]

@DieselWig, @littleteapot

Thanks for the info gents... I definitely think it was a regen as it hasn't happened since Monday.

My thermostat is goosed so I guess the engine doesn't get hot enough which caused it to smoke for longer than it should have and maybe the pre-cat not getting hot enough. I didn't check the mpg reading on the BC but I will bear this in mind for next time, however, I was under the impression that one of the lights (coil?) on the dash would have flashed during a regen.

I also need to check the front-flex....

Once again thank for your help.

[Teapot]

Thermostat replacement is very easy on Z19DTH engine, strongly recommend you do it asap.

Early software versions did flash the glow plug light during regen, but too many hapless owners who couldn't be bothered to RTFM were taking them back to the stealers becuase they thought it indicated a fault, so they removed that feature from all later software :-(

[d_ghedia]

This regen happened again. How often does this usually happen?
it was still regen-ing when I arrived at home, should I have waited for the cycle to finish or would be ok to stop the car mid cycle?

How can I check if the dpf is blocked, faulty or if it needs replacing?
I guess I would be better off removing the dpf all together with a new zorst.

[ThatAudioBloke]

If there's someone local to you with Tech2/vauxcom/opcom you can check the saturation level of the DPF. You really shouldn't interrupt the regen cycle though. If you have a motorway near you, give it a good 3rd gear blast for a few miles (not economy driving by a long shot but should get the EGTs up enough to successfully do a regen) and then have the saturation level checked again.

If you want to remove the DPF, then you'll need it mapping out of the ECU as well. Also rather than remove it, just have it's insides knocked out as there was something about DPFs possibly being a MOTable item (I'm not sure on this one though)