This fault has been going on for several weeks and I understand Vauxhall have had a look at the problem and not been able to solve it. To be fair to Vauxhall not sure what level of diagnostics they did or were allowed to do by customer. Also along the way the EGR valve has been replaced ,coolant temp sensor, vehicle oil /filter and air filter replaced with no improvement.

Code scan of engine shows no fault codes. Also the glow plug symbol is flashing indicating the DPF needs regenerating.

The fault happens as follows . Start engine and drive for 2-3 miles , then all of a sudden get really thick white smoke from exhaust . This smoke is definitely unburnt diesel , not steam. If you park the car and leave it idling it continues to belch out smoke. However if you switch off the engine and restart NO MORE SMOKE. Can rev the engine freely and only usual slight diesel puffs evident on WOT. Then drive it a short distance and smoking restarts again.

The Launch shows a MAF delivery of say 26kg/H air flow and the Calculated air flow shows 60kg/H whilst idling and as you rev up the engine the MAF value increases but is always a lot less than the calculated value. The MAF is working , but puts out a frequency based voltage which changes value as engine is revved. However I have no info on what the value should be of the output frequency against different input and at a cost of over £150 I have little reason to change this part in an attempt to get a fix.

Also my Launch is showing DPF filter measurement of 114% , i.e. is this suggesting filter is more than totally blocked? Not sure what this is referring to.

I need to do further diags on Monday and check injectors to ECU control , already done leak offs and all are same average value so not any abnormal
leaky injector.

I know there is a software update for the ECU regarding DPF regen according to Autodata and will need to find out from Vauxhall what this is all about , however I have no fault codes to suggest this problem. Also lots of issues with the injector plug no 3 needing replacement due to various issues on this engine.

I suspect the fault may lie with the DPF , perhaps the smoke is a regen starting during the drive? but why does it continue when slowing down and just idling. I thought regens only continue above say 25 mph and it would stop regen if high enough speed not attained. The difficulty is that I would like to take this for a decent run to allow the regen to happen but worried about the amount of smoke and getting stopped as well as the environmental issues.

If not a regen then possible low compression or ECU timing problem to injectors causing misfuelling. But no misfire is detected when smoke starts and engine drives smoothly except for masses of white smoke.

Hopefully somebody out there can point me in the right direction as always any help appreciated.

George