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Alright, this is going to be quite a long troubleshooting description of a DPF, Check Engine and ESP lights, so sit back :).
I just replaced the intercooler (which was leaking oil) around 2000km back, when on a morning, right from when I turned the key, the DPF light came on. It then started flashing after about a minute, and then the E-Light and ESP lights came on exactly 20 seconds after that, and the car went into limp mode.
Ordered an OBDII scanner, checked the fault codes, and they came back as P242F and P2458 (screenshot attached). I tried clearing them, and all it did was turn off the E-light and ESP light for 20 seconds (codes also disappeared for the said 20 seconds), but the DPF light kept on flashing. After 20 seconds, limp mode and Christmas tree of lights on the dash again. Most probable cause that came to mind was that since I replaced the intercooler, the oil which was leaking out of it was going into the engine, producing tons of soot and ultimately blocking the already not-so-clean DPF (last time I remember being on a highway was before the repair). Went out, got a full tank
of premium fuel and added a DPF cleaning additive, drove 200km in 6th keeping revs at 2.5k (Catalyst temps from the OBDII reader were above 300C for more than an hour), but absolutely 0 improvement. Which looking back to it, is not too surprising, I had no signs of a blocked DPF in the first place (no smell, loss of power, smoke, rough idle, anything). Came back home, disconnected battery for 15 minutes, and the fault represented itself in the same exact way as it had the first time (video here). I also tried the procedure which worked for me when the DPF light came on in the past (with no E or ESP lights), which is jumping the top right pin on the 6-pin connector to ground and pressing the accelerator pedal 10 times with ignition on, obviously, to no avail. On top of all this, engine is working just as smooth as it was before, no fluctuations in RPM, no smoke, smooth and just great, but with really little power now (by the way clearing the DTCs while engine is running produces a 20 second window of normality). So my best guesses at this point are either a very stubborn ECU that is asking for service or something (this light appeared in between driving cycles, right at the start of the day), or a faulty sensor somewhere. I really want to deal with this myself in the cheapest way possible, since I don't plan on using the car much longer before getting a newer one (we're talking 2006 here), so any tips on even just not fixing it but just turning the damn lights and limp mode off will be greatly appreciated (since I literally can't feel or hear or see even a single thing wrong with the car). Also, just any tips on what sensors to check are also appreciated.Thanks in advance for any answers and thanks for reading into such lengthy description!
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Um, WHY was there oil in the intercooler? It doesnt hold oil, so you need to address THAT first.

Went out, got a full tank of premium fuel and added a DPF cleaning additive
UM.... WTF??? Diesel doesnt come in octane grades...
 

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Um, WHY was there oil in the intercooler? It doesnt hold oil, so you need to address THAT first.



UM.... WTF??? Diesel doesnt come in octane grades...
Well, the only source of oil in the intercooler that I can think of is the turbo spitting some. It wasn't pure oil, it was much thinner so it was oil mixed with a bit of condensation. Since my intercooler was cracked, it didn't hold pressure, so it generated a stronger vacuum when letting go of the throttle (a bit counterintuitive here but I hope you understand what I mean) that sucked oil out of the turbine. I have no way of checking if there is oil there or not now that it is sealed and holds pressure properly, but no signs of it really, so I would call it addressed already with the intercooler replacement.

Regarding premium diesel,
there are higher cetane grades, not octane + cleaning additives (mainly nitrogen based) that are in premium diesel fuel here. They do in fact make the engine run a bit smoother by cleaning the injectors a bit and overall having cleaner combustion when you run 2 or 3 full tanks though.
 

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No, if you have oil in your IC, then you need to address that first... what part of "it doesnt hold oil" is hard to understand? No, vacuum cannot suck oil out of the turbo... a cracked IC doesnt increase the vacuum the engine can pull.
 

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No, if you have oil in your IC, then you need to address that first... what part of "it doesnt hold oil" is hard to understand? No, vacuum cannot suck oil out of the turbo... a cracked IC doesnt increase the vacuum the engine can pull.
Yes, I understand it is not supposed to have oil in it and I understand that a vacuum should not pull oil out of the turbo. But in my case the failing turbo does indeed spit oil when exposed to vacuum, which ends up in the IC. The vaccuum was stronger with the cracked IC, in my understanding, because instead of pulling the pressurized air (say .3 bar of positive pressure and dropping it to -.1) it was pulling atmospheric pressure down to, say in this case, -.4 bar. I understand that ideally I’d need to address it as it is the root cause, but I do not want to spend on a turbo what would be in my country the amount of money I spent on my car, especially because I am upgrading soon. Anyways, I solved the check engine problem.
Ran the clearing cycle (top right pin in the breaker box short to ground + 2 full throttle presses), but nothing happened. I then disconnected the battery and ran the cycle before the DPF light had a chance to appear. The cycle finished about 80 minutes in and no lights are on the dash anymore :) .
 

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Yes, I understand it is not supposed to have oil in it and I understand that a vacuum should not pull oil out of the turbo. But in my case the failing turbo does indeed spit oil when exposed to vacuum, which ends up in the IC. The vaccuum was stronger with the cracked IC, in my understanding, because instead of pulling the pressurized air (say .3 bar of positive pressure and dropping it to -.1) it was pulling atmospheric pressure down to, say in this case, -.4 bar. I understand that ideally I’d need to address it as it is the root cause, but I do not want to spend on a turbo what would be in my country the amount of money I spent on my car, especially because I am upgrading soon. Anyways, I solved the check engine problem.
Ran the clearing cycle (top right pin in the breaker box short to ground + 2 full throttle presses), but nothing happened. I then disconnected the battery and ran the cycle before the DPF light had a chance to appear. The cycle finished about 80 minutes in and no lights are on the dash anymore :) .
There should be no vacuum in the induction system after the turbo but a positive pressure.
If you have got a vacuum then your turbo isn't turning. Any oil in the IC is from leaking turbo seals, so as Talon said look at your turbo.
You do not 'pull' pressurised air.
A cracked IC is more liable to blow air out to atmosphere as its pressurised or should be if your turbo is working. You do not get a vacuum and a pressure in the same enclosed space.
A turbo charger is an exhaust gas driven air compressor, the air compressed heats up and so has to be cooled by passing through the intercooler (put your finger on the end of a bike pump and try pumping, your finger will become hot) conversely expanded pressurised air cools down and can form frozen condensate. This pressurised cooled air then feeds into the cylinders as the air inlet valves open. The greater mass the of air the more fuel that can be injected and hence more power produced. Inject more fuel without the corresponding increase in air and you produce black smoke.
Do you get black smoke when you floor the accelerator or any turbo lag?
 

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There should be no vacuum in the induction system after the turbo but a positive pressure.
If you have got a vacuum then your turbo isn't turning. Any oil in the IC is from leaking turbo seals, so as Talon said look at your turbo.
You do not 'pull' pressurised air.
A cracked IC is more liable to blow air out to atmosphere as its pressurised or should be if your turbo is working. You do not get a vacuum and a pressure in the same enclosed space.
A turbo charger is an exhaust gas driven air compressor, the air compressed heats up and so has to be cooled by passing through the intercooler (put your finger on the end of a bike pump and try pumping, your finger will become hot) conversely expanded pressurised air cools down and can form frozen condensate. This pressurised cooled air then feeds into the cylinders as the air inlet valves open. The greater mass the of air the more fuel that can be injected and hence more power produced. Inject more fuel without the corresponding increase in air and you produce black smoke.
Do you get black smoke when you floor the accelerator or any turbo lag?
 

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There should be no vacuum in the induction system after the turbo but a positive pressure.
Negative. At idle and decel there is only vacuum.
 

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There should be no vacuum in the induction system after the turbo but a positive pressure.
If you have got a vacuum then your turbo isn't turning. Any oil in the IC is from leaking turbo seals, so as Talon said look at your turbo.
You do not 'pull' pressurised air.
A cracked IC is more liable to blow air out to atmosphere as its pressurised or should be if your turbo is working. You do not get a vacuum and a pressure in the same enclosed space.
A turbo charger is an exhaust gas driven air compressor, the air compressed heats up and so has to be cooled by passing through the intercooler (put your finger on the end of a bike pump and try pumping, your finger will become hot) conversely expanded pressurised air cools down and can form frozen condensate. This pressurised cooled air then feeds into the cylinders as the air inlet valves open. The greater mass the of air the more fuel that can be injected and hence more power produced. Inject more fuel without the corresponding increase in air and you produce black smoke.
Do you get black smoke when you floor the accelerator or any turbo lag?
Negative. At idle and decel there is only vacuum.
Talon, at idle there is still exhaust gas passing through the small tbb and thus developing a pressure. See attached. The engine is at idle
798 rpm, with 0.12bar pressure in the inlet system. I very much doubt there will be a vacuum on deceleration, but not able to check that at the moment. You have to realise this is a diesel not a petrol. The only time that there would be a vacuum is when the butterfly closes when you turn the engine off, which reall doesn't count. Normal running there will always be pressure due to the turbo spinning and producing scavenge air. I will stand to be corrected with screenshots but not words.
The tbb would have to be stationary whilst the engine is running for a vacuum in the manifold and thus wouldn't work.
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Talon, at idle there is still exhaust gas passing through the small tbb and thus developing a pressure.
Do you understand what my name represents? I know a shit ton about turbos and those motors, there is no such thing as a non-vacuum ICE. Why must you ALWAYS argue with me and try to prove me wrong?
 

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Talon, 0.12 bar is not a vacuum, it is not a case of arguing, what cannot speak cannot lie.
So what is your background, please do tell and what academic qualifications (not mechanics black fingers) do have regarding diesel engines?
As a piston goes down on the induction stroke it would tend to pull a vacuum , but as the inlet manifold is charged with pressurised air from the Turbo then no vacuum exists.
The intercooler is always under pressure and regulated by the bypass valve/ wastgate valve into the exhaust system from what I see from the diagrams. Hope these will be a help to anybody to see the overall system.
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Listen here redcoat... at idle and decel the turbo DOES NOT PRODUCE enough boost to overcome the vacuum. Hook a real boost/vac gauge up to the intake mani and read that and youll have to come back and admit youre wrong.
 
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