Grey smoke on normal driving / pulling away

Putting this in the performance section because it could be directly related to my injectors (Firad +80s) or it might not.

Basically I am noticing more and more now my car is emitting a grey smoke just pulling away / using light power in 1st and 2nd gear. It might do in third too but at speed it's not as clear to see in the wingmirror (side exit exhaust).

Since my track session a couple of months ago, and my 2 track sessions on Saturday, it seems to be getting ever so slightly worse. I have a full trackday booked and paid for on 8th October so would like to maybe get this at least diagnosed even if I don't get it fixed in time.

On track, weirdly, the car has been noted as being quite clean (for a car approaching 300bhp without NOS) with not much smoke on full chat, full boost, etc. It's just this slightly (anti social too) annoying grey smoke on normal driving. Also, I have watched the smoke as I go from "normal" to "brisk" acceleration and it just changes colour from light grey to dark grey.

First thought is a potentially broken nozzle which might mean it is pushing in a bit too much fuel on just light driving. It cannot be too excessive anyway as I am not getting any worse fuel economy than normal at the moment. I have full VCDS so could log fuelling, if VCDS could pick up a dodgy nozzle. I have no way to diagnose anything though so would need pointing to the right group to log.

I am also getting minimal oil usage, so I am assuming the smoke isn't oil related (suggesting serious bottom end issues)


Here's me just on light load in a corner on Saturday


and this is full load, main straight

Timming too late at light et partial load?



Dieseleux

dieseleux said:

Timming too late at light et partial load?



Dieseleux

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if it had always done it since day 1, I might have agreed with you, but this has only been noted in perhaps the last 12 months, but getting a bit worse during the past 6 months. It is a little like something is degrading / failing somewhere to cause this.

it is also sort of linked in to the cold start smoke issue thread I popped up that was seemingly cured by a change of alternator and the battery getting juiced up again. I am still getting a bit of cold start smoke too. Perhaps I will try hooking up a trickle charger to the battery to see what effect a boost has.

Cheers.

You have a new turbo installed right? much bigger I remember. Its not going to spool the same and you'll probably have to update the tune for it.

I'd still check the timing as I've seen timing drift as the belt stretches cause a similiar issue on my passat.....after I'd adjusted the timing the smoke reduced.

JFettig said:

You have a new turbo installed right? much bigger I remember. Its not going to spool the same and you'll probably have to update the tune for it.

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I do, and have a map to go on, however this light grey smoke is only when pulling away with no boost at all (or very minimal boost indeed)

Its possible your other turbo had enough boost in those situations to clean that up where the new turbo isn't flowing enough in that situation.

Jase, my motor has started to do this after the track day (im the 2nd car in the photo).

On light throttle I get a fair bit of grey smoke but when on boost it clears up. No help to you I know but would love to know the cause.

I thought it was turbo related, as for the day I had the tune turned right up, but maybe not ?

Running stage 2 pd150 hybrid with normal injectors

O2 sensor install?



Dieseleux

Boost pressure / fuel-air ratio is not relevant for pulling away/low-load, especially if, as it sounds, it was fine before and the smoke developed over the course of some time with no stated change in hardware.

Pull the injectors out and have them pop/spray tested. You might have one of more dribblers/streamers. Check your compression too while the injectors are out.

Before turbo spool, is very easy to put too much fuel, the owner of powerful engine dont see easily if the engine have too much fuel at low rpm and low boost, torq is addictive!




Dieseleux

I know this is a really old thread but was the cause ever found out of this grey smoke at pull away and very light throttle in 1st and 2cnd?