Re: A6 2.5TDI Smoking + ultrasonically cleaning injectors

No white smoke on start-up. Well, not that I've noticed anyway. Exhaust points down, and I'm never in a position to see it when I'm starting the engine!

I thought the point about snake oil is that it lingers in the system, potentially causing future blockages??

Cool, that puts my mind at ease. I want it to have a really decent effect, so I'd rather put more in and have more smoke in the short term, but a longer lasting effect, rather than it just having a gradual effect - by tank takes about 78 litres at most (so not quite 20 gallons) - would 2 litres in a whole tank be too much (is there any potential damage it could do) or should it be ok?

Also, you say you've tried it - have you tried on VAG TDI engines before?

Peter

-- "The truth is working in television is not very glamorous at all. I just go home on my own at night and sit alone and eat crisps."

system,

He-he :-) "Snake oil" is just a generic term for useless products. AFAIK it originated in the Wild West when medicine salesmen sold quack medicine as a cure-all.

No potential damage and it will be OK. I would try a maximum of 1.5 litres at first. Use up threequarters of a tankful of the treated fuel then top up with diesel only for the second tankful. By the time you use most of the second tankful you should find a very significant improvement. If not, try again. If it doesn't work then, the injectors need calibrating. This is unlikely though not impossible.

As to speed. Nothing works instantly. Think of a washing machine full of clothes. It takes a couple of hours to wash, then they need to dry and be aired and ironed before they are clean and fit to be worn again. Much less palarver is involved with useing an additive like ATF to clean the injectors. Just apply, use and wait for results. Best to forget about it for a week afterwards before checking the smoke. Otherwise it is rather like watching paint dry or yourself growing old; nothing much happens from minute to minute.

No but I have used it with good results in a Toyota high pressure fuel system and various other diesel vehicles only on an 'as needed' basis. Remember to mix well. I fill the tank about a third full and add a third of the mixture, fill to half full and add half of the remainder and then add the rest at around the 3/4 mark. No need to be *that* precise but remember that when fuel is concerned "cleanliness is next to Godliness"

Huw

decent

then,

No, I mean taking the injectors out to spray and pressure test them. Crack-off pressure falls off over time and also fuel volume injected gradually increases, usually to the actual benefit of less noise and more power to a point. That point is where soot emissions become unacceptable to the extent that either you are concerned or it fails the MOT soot test.

I don't know whether your engine is a standard unit or a Pumpe-deuse. Either way, your mileage should not cause this kind of concern. But you never know. There is a bit of luck involved with running any engine.

If you are still concerned after doing the cheap additive trick as I described, then take it to an MOT station and ask them to actually do a soot test. They will be able to give you a proper measure of the soot to either confirm your anxiety or take a load off your mind.

Huw

Yeah, I think the fact that it's quite a freely revving diesel engine means that the power is easily accessible and it's quite easy for it to overfuel a bit.

It's just a standard one. Proper old-skool design, dating back to 1991!

As far as MOT soot tests goes it's fine - it's only when it's under load under hard acceleration, or actually during acceleration generally, that it smokes a bit. I'll give the ATF a try as you've suggested and let you know how I get on.

Anyway, cheers for all the advice. Good, this internet thing, innit? I'd happily repay the favour if you ever need any help with talking s**te or telling mildy amusing stories.

Cheers,

Peter

-- "The truth is working in television is not very glamorous at all. I just go home on my own at night and sit alone and eat crisps."

them.

injected

fails

engine

It is a diesel engine and that should not happen at any revs. It is governed and turbocharged and, in your case, electronically managed. It should not smoke *significantly* at any revs, though it could give the occassional puff when suddenly accellerated from low revs. To gauge what is 'significant', take it for that smoke test.

Not in an A6 it's not!

innit?

Thank you I'm sure.

Huw

The other obvious thing to check is the actual boost pressure. If that's fine then check the injectors.

What's not? Are you saying that the 2.5l in-line 5 cylinder diesel engine isn't 'proper old-skool design', or that it doesn't date back to

I am saying that in the A6 it has the emmissionised version of the engine. I do not have intimate knowedge of this particular version but I suspect it differs from earlier versions substantially, depending on model year, by having electronic control of the [higher pressure Bosch VP3] injector pump. Latest versions *might* even have switched to PD which is different again.

Now, I am not certain of any of this because I have lost contact with things VW in recent years, but whatever version is involved, it does not alter the jist of my previous posts as the engine version is largely irrellevant to basic diesel operation.

And yes, someone said to check boost pressure. Well worth checking at some point, though I personally have never had a problem with this over many engines. There can be problems with air pipes sometimes delaminating internally which can restrict air flow. That's another possibility. In fact there are a heck of a lot of possibilities, even that there is nothing wrong at all.

Huw

If you have power loss and no smoke then in typical VAG fashion the MAF is buggered. If not then the MAF is fine- you wont get excess smoke from a faulty MAF.

At 125k or so the injectors are well past it- have them overhauled if it is getting abit smokey- likewise clean out the EGR system, and if possible blank it off- this is a major cause of excess smoke.

If you're really going for it, you might hook up a boost gauge and check what level its at- with age and heat the wastegate springs go weak so you dont get factory boost- this can (not always) cause abit more smoke than it should do (with a factory set max fuelling setting)

Tim..

They really shouldn't be, although they could be. I've never had a general wear or maintainance problem with them at this mileage on a modern engine although the very occasional one does actually fail in some way.

have them overhauled if

Yes, all those vacuum operated valves which restrict air flow etc and which rely on small capillary tubes are a potential nightmare. I've long rendered my Isuzu's system inoperable due to problems. My Toyota OTOH has been no bother in this area, neither have the Nissans. Yet.

Huw

Nedavno Huw pise:

| cheaper, is a litre of ATF [automatic transmission fluid] for every 20 | gallons of diesel in the tank. This is only needed once [a year | perhaps] and, in the case of ATF, will take the consumption of a | tankfull or two to work, but work it will.

Can ATF be added in a petrol engine for injector cleaning (NF 5-cylinder

Injectors are past their best at 80k. At 125k they'd be shot. You dont notice the fall off in smoothness, and performance until you fit a new / recon-ed set.

Tim..

I have absolutely no idea. Unless someone comes up with a positive report, I would *not* try it if I were you.

Huw

mirror

smokes

Obviously

should

Toyota

Not my experience I'm afraid. All I can go on is my experience, but it does cover a huge number of engines. Within reason, the more an injector is used, the smoother the combustion, though ultimately the injectors do wear of course. I have changed several sets of injectors [before I started to use ATF] with either no result, or twice when the proffessionaly reconditioned injectors were worse than the original ones with over 100k on them. Similarly with injector pumps. Between my own fleet and indirectly maintaining a large park of other vehicles, I find quite a few [mainly] rotary injector pumps that need maintainance/repair every year. The other day one of a fleet of Nissan vans came in as a result of the driver opening the fuelling out and upsetting something internally. Sent it away to one of the most reputable frachise specialists in the Country and it came back exactly the same, with shovel loads of soot coming out of the exhaust. Second time lucky though.

To put some figures on injector wear, I have found that the average use before an injector actually needs some work done to it is about every 450,000,000 cycles. This equates to about 150,000 miles on average I would have thought. I have one Mitsubishi Shogun with the old 2.5 indirect injection engine presently that has led a very hard life, with much heavy towing and its share of two minute runs, and which has never had its fuel system touched apart from filter changes. 145,000 and it smokes and runs no worse than new. Unless an injector suffers a catastrophic failure, I can see no reason to change or touch the injectors any time soon.

My moto has always been, "if it ain't broke, don't fix it, but if it is broke, get the job done quick"

By the way, My BMW 3.0 diesel needed a single new injector at around

Huw