S320CDI Power Loss + Excessive smoking

[aka$h]

On acceleration, the car lacks power, until around 2000rpm, then a surge of power and clouds of black smoke. The lower part of the rev range is where the problem lies.

Ive had the mas sensor replaced,
both the cats have been bypassed to eliminate excess back pressure.

When on STAR the following tested OK:
Turbo waste gate
the 2 tranducers

the only issue is EGR rate too low, not sure if this is related or not. Other than that there are no faults present.
the rail pressure is fine as are all the injectors.

Ive had it into a couple of specialists but no-one has seen the problem before, what should I look at next?

 

[BlackC55]

Egr. Thats the first port of call for me.

 

[aka$h]

Egr. Thats the first port of call for me.

The actuation works as it should when on STAR, is it worth removing? If so, what should I expect to see, would it be blocked?

 

[BlackC55]

Expect to see it clogged up with oily slime/gunk. It is possible to clean them. Try that first.

A new one is about £270, so its worth cleaning it to try.

 

[jaymanek]

Injector problems?

 

[Dieselman]

I'd go with BlackC55, sounds like the EGR valve is stuck hence the low reading on Star.

 

[aka$h]

Thanks for the advice chaps.
I spent the afternoon taking the turbo out and took it down to a turbo specialist. It seems the turbo seals have been leaking and hence oil has been getting into the turbines causing smoke. This is most probably the cause for the smoke, but the power loss is a seperate issue.
I plan to remove the EGR unit tomorrow and see if it clogged up, and also remove the intercooler and ducting. I plan to give everything a good clean and hope for the best.
Thanks again!

 

[Dieselman]

The turbo won't cause black smoke, it'll be blue. I still think EGR valve.

Good luck.

 

[Dieselman]

If you want to give the injectors a clean try some biodiesel through the system it will de-gum the fuel system end to end.

 

[Glenn Smith]

Too much EGR, due to a faulty valve can cause serious running problems, i have had experience on a VW of this happening, the problem is that the air mass meter only sees air coming in, this air is reduced by the excessice exhaust gasses in the inlet, often this is not recorded as a fault, with the vw's we have to run the car under full load and take the air mass readings and compare with the readings you should get. Try blanking off the egr valve, usually you can make a plate to fit the exhaust or inlet manifold, note you have to blank off the valve not the control hose.

 

[A HEARN]

hi i have 2001 s320 and i have the same problem did you get yours sorted out and so what was the out come

 

[aka$h]

Update,

Over the past week the following have been carried out:
1: remove intake manifold, this was cleaned, and the flapscheck, none stick and the motor operates correctly.

2: remove EHR valve, this was pretty bad, now the egr values read as expected.

3: remove turbo charger, this was fully reconditioned due to a leaking oil gasket.

4: remove turbo pipes, these were cleaned and retitted.


Unfortunatly the fault still remains, the car has what seems like a very long lag, but after 2000rpm it gets up and goes.

two points to mention:

1: the charge air temperature seems to be high, its around 48 degrees DAS states it should be below 40.

2: the pipe coming off the front of the turbo going into the intercooler, has come off twice in 20 mins of driving, the clips are holding well as I found not pull it off by hand no matter how hard I tried.

Can anyone suggest what I can try next?

 

[Harley Man]

Have you cleaned the intercooler? could be partly blocked, and have you changed the MAP Sensor? could be its telling the ecu there is boost when there is not.

 

[Dieselman]

Is the turbo vane ring moving freely as it could be sticking in higher speed operation, so underboosting at low revs.

The charge temp sensor could be faulty or as Harleyman says the intecooler could be dirty inside or out.

Have you tested the injectors for dribbling. Try some injector cleaner or Biodiesel to clean them up.

The charge temp can only be as a result of high ambient temp, overboost or lack of intercooler efficiency.

Overboosting can be as a result of overfuelling as that increases the exhaust gas temp.

Connect a boost gauge to the MAP sesnor line and a seperate temp sensor into the intake. An inside/outside thermometer will work for this.

Measure the charge temp before and after the itercooler to check efficiency.

 

[aka$h]

Have you tested the injectors for dribbling. Try some injector cleaner or Biodiesel to clean them up.

Ive used an injector cleaner, bt how would I check for dribbling? On DAS the injected quantitys are well within tolerance, and the amount compensated is almost nil.

 

[Dave K]

Did you actually change the EGR valve? My 320 CDi had the exact same symptoms as your. Cleaned the EGR valve but the problem remained. Swapped it for a new one and problem solved.

 

[IBIZA]

If you want to give the injectors a clean try some biodiesel through the system it will de-gum the fuel system end to end.

Frequently after doing this it can be worthwhile to change the fuel filter or carry spares and the kit to change it with you. Biodiesel has a very powerful cleaning action and if switching to run on it, or using it as a flush, anything not going through the injectors will work its way back round to the filter.

This can happen fairly gradually, in that you will first notice a lack of acceleration when you go to overtake, or can seem to happen fairly suddenly when you realise to maintain speed your foot it fully on the pedal and the engine stops when you lift it.

I run cars on vegetable oil (and have informed HMR&C) which I thin with biodiesel for colder weather. Before starting this with each car - I flush them with 100% biodiesel, until they have gone through a full tank without filling a filter. One car with only 58,000 miles filled four filters (but had been sitting for over a year when i got it).