Black Smoke on hard accelleration or under load

[rovertone]

My car runs an absolute dream, has 160 remap and have just completed 3K round trip to Algarve achieving 43.5mpg at a fairly rapid pace and fully loaded which I think is acceptable for an auto. Mileage 128K

My problem, as the title suggests, is a black smokescreen when I boot it hard which clears as soon as I ease to cruising. This is also noticeable when under load towing my caravan. I can be climbing an incline at steady throttle and all is ok, if I put on a bit more power I get black smoke, ease off and it disappears, on and it returns.

I have had this problem more or less since I had the car at 92K (pre remap), there has always been a soot mark on the rear bumper after a long run. I would certainly have failed the last 3 MOT's on smoke emissions had it not been for a 'friendly' tester.

I have done all the usual items, new MAF (didn't real need it), upgraded PCV, cleaned out EGR & manifold, I/C hose all good new 'O' rings fitted, new air filter, fuel filter, replace stat & water pump (engine now runs correct temp).

Not sure where to look next, as stated the car runs really well but given the focus now on diesel emissions I am thinking that my MOT man may not be able to be so 'friendly' in future so need to try and sort this.

Maybe a T4 health check? Nothing showed up on remap at c96K.

Any suggestions would be most welcome
Thanks Tony

[RogerHeinz57]

Most of the diesels smoke a some stage of accelerating, makes little if any changes if you run it on Shell or other proper fuels against cheap supermarket fuel. The power upgrade will make more smoke due to elevated fuel pressures and greater amounts of fuel injected, and as you clearly have done most of the obvious fixes, there is one that not many have spoken about.
It is not uncommon for the turbo seals to allow a small amount of oil through to the lower hose attached to the intercooler, this is again quite normal and no real problems to the car, but the long term effect is this.....
The intercooler has a small puddle of oil at the bottom, when the charge is generated by the turbo unit, it enters the intercooler, whips up a nice oil contaminated mist collectively with the hot gasses and then is introduced into the inlet tract and then off it goes into the engine and becomes burnt causing noticeable smoke.
This is worsened by the fact that the intercooler internals are heavily coated in oil from many years of punishment of hot gasses and oil mist. The efficiency of the cooler is marred and the engine fueling will be right but the gasses will contaminate everything it travels through ! On my car which has the 160 and also a synergy 2a on mid settings smokes fairly well under heavy load usage, the plan is to remove the intercooler and clean out with brake cleaner thoroughly, This will enable fresh intake gasses cooled properly.

Sorry for the long winded reply, but you did ask for info !

[rovertone]

Thanks for that info, problem with intercooler had crossed my mind but more on the basis of having a leak, hadn't thought about oil contamination choking it up.

First chance I get I will strip it off and give it a good clean.

Thanks again for the 'heads up'
Tony

[marinabrian]

The main reason a car produces smoke is if there is insufficient air to completely combust the fuel being injected.

Prime suspects are intercooler hoses, o rings and associated pipework.

That is not to discount other variable such as injector spray patterns, MAF sensors etc etc etc.

It is fairly easy to pinpoint any deficiency using the live data from T4, but running a finger under the intercooler hose at the bottom is a good start

Brian

[rovertone]

Thanks Brian,
I'll have a feel under the pipe tomorrow although it all seems generally dry around the joints.
It's a while back now but Terry at TS autos fitted viton rings to the intercooler hose (adding a 3rd) after I found a Spanish garage had thrown it back together after fitting a new rad. He (Terry) commented that the intercooler hose, whilst intact, was quite soft, I assumed that it was probably silicone but am now wondering whether that's distorting.
Maybe it will need PhilT4 to give it another check, not sure whether he is back in action, I did read that he was not so well. The frustrating thing is that it runs so well but it's obviously not right.
Thanks again for your input.
Tony

[HarryM1BYT]

Originally Posted by rovertone

Thanks Brian,
I'll have a feel under the pipe tomorrow although it all seems generally dry around the joints.
It's a while back now but Terry at TS autos fitted viton rings to the intercooler hose (adding a 3rd) after I found a Spanish garage had thrown it back together after fitting a new rad. He (Terry) commented that the intercooler hose, whilst intact, was quite soft, I assumed that it was probably silicone but am now wondering whether that's distorting.

Tony

If its black and soft /rubbery, it will be the original hose which tend to swell and become porous, so worth changing for a modern, shiny silicone version.

The other thing you didn't mention trying, is injector cleaner. Take the fuel filter off, half fill with injector cleaner, refit, start and run the engine for a few seconds, then leave it to work on the injectors over night.

[bl52krz]

Also have a look at your air filter.

[grivas]

Originally Posted by RogerHeinz57

Most of the diesels smoke a some stage of accelerating, makes little if any changes if you run it on Shell or other proper fuels against cheap supermarket fuel. The power upgrade will make more smoke due to elevated fuel pressures and greater amounts of fuel injected, and as you clearly have done most of the obvious fixes, there is one that not many have spoken about.
It is not uncommon for the turbo seals to allow a small amount of oil through to the lower hose attached to the intercooler, this is again quite normal and no real problems to the car, but the long term effect is this.....
The intercooler has a small puddle of oil at the bottom, when the charge is generated by the turbo unit, it enters the intercooler, whips up a nice oil contaminated mist collectively with the hot gasses and then is introduced into the inlet tract and then off it goes into the engine and becomes burnt causing noticeable smoke.
This is worsened by the fact that the intercooler internals are heavily coated in oil from many years of punishment of hot gasses and oil mist. The efficiency of the cooler is marred and the engine fueling will be right but the gasses will contaminate everything it travels through ! On my car which has the 160 and also a synergy 2a on mid settings smokes fairly well under heavy load usage, the plan is to remove the intercooler and clean out with brake cleaner thoroughly, This will enable fresh intake gasses cooled properly.

Sorry for the long winded reply, but you did ask for info !

Should the smoke then be more blue than black if the engine is burning a little oil? or am I looking at it wronngly?

[Avulon]

Originally Posted by grivas

Should the smoke then be more blue than black if the engine is burning a little oil? or am I looking at it wronngly?

It'll be black - the oil in the intercooler is most likely as black as pitch already with soot contamination (as is the oil in most diesels just a few miles after and oil change).

[75driver]

I put the intercooler o rings in, and fitted them in from the top (bonnet), and thought I did a "sound job".
However, when I had the bumper and slam panel off to check play in the rad fan, I noticed the elbow must have rotated a bit, even though the securing bolt was in place, because the top o-ring had partially popped out and was showing on one side.
Put it all back together, from the front, and all is good again.
I'm just cursing myself that I didn't remember to put a self tapper in thru the elbow when I was at it.🙄


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