Exhaust smoking after DPF regen??

[Harrihealey02]

Hi all,

https://youtu.be/Eh8NEllE980

I recently had my DPF regen done on my drive A couple of days ago and it fixed my issues I was having with the warning lights. Now I’ve noticed a plume of smoke come out when I start it, and when I floor it there’s a bit of smoke.

I know any car with a DPF will fail an mot if tester sees any form of smoke. Is it normal for a car that’s had a regen to smoke after it’s completed? (Maybe residue ash that was burnt is still flushing out of it?)

Thanks

[SRGTD]

Hi all,

https://youtu.be/Eh8NEllE980

I recently had my DPF regen done on my drive A couple of days ago and it fixed my issues I was having with the warning lights. Now I’ve noticed a plume of smoke come out when I start it, and when I floor it there’s a bit of smoke.

I know any car with a DPF will fail an mot if tester sees any form of smoke. Is it normal for a car that’s had a regen to smoke after it’s completed? (Maybe residue ash that was burnt is still flushing out of it?)

Thanks

I don’t think there are many members on the forum with a current model Polo with a diesel engine, so you may not get many responses specifically in relation to to the Polo.

I’ve had two diesel Golfs with DPF’s - a mk5 (Euro 4 emissions standard) and a mk6 (Euro 5 emissions standards) and can’t remember them ever producing visible smoke, and the chrome tips on the exhaust also stayed clean. I think the current Polo is Euro 6 emissions certified, and with emissions standards being more stringent now, I’d not expect a car that’s Euro 6 (or later) diesel to produce noticeably visible black smoke.

[Harrihealey02]

I was thinking the same. My conclusion is there’s unburnt diesel in the DPF that’s now being burnt. What’s weird is it happens when I start it up, and if it was pure diesel smoke coming out it wouldn’t usually happen at start up, only when you’re flooring it and for the whole time you are flooring it. I will give it a couple of days (if I get the chance to take it out) and see if it’s gone. Thanks for the reply.

[monkeyhanger]

My wife's 2013 Audi A1 had the 116ps output version of this engine. The output from the exhaust was always smoke-free and the exhaust tip was spotlessly clean with no hint of soot.

That car looks like it has no DPF at all - I wonder if the DPF honeycomb matrix has fractured?

Is the exhaust tip sooty?

That's almost certainly not ash pouring out of there. Ash is the incombustible portion of exhaust gases that the DPF can't process (minute amounts of inorganic impurities in the fuel and oil - mainly from oil), it builds up in the DPF until the DPF has no storage capacity for soot. The Ash never gets out unless you get your DPF professionally flushed, and the car will be be generating maybe 8g of Ash every 10k miles unless you've got a chronic oil consumption issue and you've been using non-synthetic oil with a high ashable content.

How many miles a day do you typically do in your car? DPFs are a lot better than they used to be, I've had 4 VWs and the Audi A1 with DPF equipped TDI engines. The more recent ones have the DPF right on the exhaust manifold for very quick warm up. EU6 compiant diesels should manage at least 800 miles between active (when the car is deliberately instigating regeneration by burning fuel in the exhaust system) regens if you're doing at least 8 miles on your commute. I was doing 20 miles each way a few days a week to keep the DPF clear when the wife and I swapped cars. I could hammer that car and it still gave 65mpg, with all regen occurring passively.

How's your idling speed and fuel economy? You should see idling speed increase from 850 to 1200rpm during an active regen, with a fuel economy drop of about 15%.

[Harrihealey02]

After the first AA technician cleared the codes the car showed the "Particulate filter: see owners manual!" Message on the dash Which was a good sign as this is what I should have initially seen. I took it for a drive straight after he left and the engine was idling higher (1000 rpm) and the fans were going loud, (which didn't happen at all when the warning lights were initially on before the AA technician came)
I know it was doing a regen as it had an acrid smell and you could hear it when I was stopped.
I took it for a long run yesterday and I still saw the smoke, but this morning I took it out and I didn't notice any in the mirrors when I started it. I hope it is going away! I'll see how it is later.

[monkeyhanger]

After the first AA technician cleared the codes the car showed the "Particulate filter: see owners manual!" Message on the dash Which was a good sign as this is what I should have initially seen. I took it for a drive straight after he left and the engine was idling higher (1000 rpm) and the fans were going loud, (which didn't happen at all when the warning lights were initially on before the AA technician came)
I know it was doing a regen as it had an acrid smell and you could hear it when I was stopped.
I took it for a long run yesterday and I still saw the smoke, but this morning I took it out and I didn't notice any in the mirrors when I started it. I hope it is going away! I'll see how it is later.

Fans blaring at idle or when you park up and switch off is a sign you're in the middle of an active or forced DPF regeneration. The car has put itself in a situation of artificially creating ideal regeneration conditions by burning fuel in the exhaust system to raise the temperature for soot combustion. When you interrupt that process, the exhaust system looks to cool itself down, hence the fans blaring

[Harrihealey02]

Good news! Doesn't look like there's any smoke coming out now. I'll keep monitoring it but I did give it a hard rev when I took off and couldn't see anything a-miss in my rear view mirrors.

[Harrihealey02]

Bad news! Car started smoking again and had a Volkswagen technician from the AA came and checked the car. He ran tests on his laptop and told me that the computer has told him that the DPF needs replacing. He reckons the cause was the EGR valve getting stuck open which caused the first issues I had with the blocked DPF and after having a regen with the stuck EGR valve it caused it to get soot up again. I'm getting a courtesy car arranged and they will arrange to pick it up to take it in to a Volkswagen garage on Monday.