Hi all,

 

I had my EGR deleted by Avon Tuning about 8 months ago and although it fixed my fault (kept going into limp mode), it's smoked quite a lot since. Car is a 2010 Mk2 Superb TDI 170 CR, auto, on about 260k now. IIRC, it started doing this pretty much straight after the work was done. I don't notice it on a run but now I'm living in London and spend a lot of time sat in traffic, it's more of a problem.

 

Journeys are often quite short but I do long trips of over 100 miles fairly often, typically every week or so.

 

Any idea what might be causing it? I read something on here about a similar problem and it was a blocked/unblocked vacuum pipe to blame, but it was a different car. I'm happy to have a good rummage around but not really sure where to start.

 

Thanks for any advice/info.

 

Regards,

 

Shaun

Smoke means too much fuel or not enough air. If this coincided with the EGR delete then I'd be inclined to blame the delete tune. These engines don't take well to EGR deletion. Your best bet is to replace your borken EGR (and probably DPF) too and restore the standard ECU mapping.

I thought black smoke might be symptomatic of that, or is that just petrol engines? It's just as bad when idling as when tootling along at 30, it doesn't do it after a longer trip.

Smoke in any engine means the fuel air ratio is not being managed properly. Since your car started this after having the EGR valve mapped out it's very likely that that is to blame. The solution is to fix the EGR instead of bodging it out of the way.

Although they mapped out your EGR, did they check the EGR wasn't stuck open, which can happen when they fail.

 

I would try fitting a blanking plate on the EGR pipe.

I haven't had the EGR deleted on my Skoda, but I had it done on a Honda once, and had the same smoking problem you describe, ShaunBillBrown. In the end it was solved just with a different map, but the next recommended step from the tuner would have been to fit an EGR blanking plate so, as PipH says, that would be what I'd try in your case.

On 01/03/2020 at 18:38, ShaunBillBrown said:

it's smoked quite a lot since.

What colour of smoke? That can be diagnostic to over-fuelling, under-fuelling, using oil, head gasket failure...

2 hours ago, PipH said:

Although they mapped out your EGR, did they check the EGR wasn't stuck open, which can happen when they fail.

 

I would try fitting a blanking plate on the EGR pipe.

They did that. It was Avon Tuning near Bristol, I think they're reputable. They've offered to look over it for me so I'll see what they come up with.

 

The smoke is white I think, it doesn't have that nice old tractor smell to it, it's quite acrid.

White smoke is usually unburned diesel - it could be that it's trying to regenerate the DPF continually because of the remap. What has your fuel economy been like since the EGR delete? I'd also be keeping a very close eye on the oil level. If it has been dumping in diesel trying to regen, you could have a lot of diesel in the sump by now.

Deleting the EGR without also removing the DPF is not recommended.

 

The EGR and DPF are designed to work in harmony, disabling one without addressing the other is the issue. The DPF is now struggling.

 

I'm surprised a reputable tuning company wouldn't know this?

Also if spotted it's now an MOT fail - and if smoking it'll fail anyway