Hi.wonder if anyone can help.i have a friend with an audi a4 2.0 TDI SE BRD engine code.the issue is that when accelerating theres no power and thick black/sooty smoke comes from exhaust until the turbo boosts then the smoke clears and runs fine until you come to a hill and power dies and the black smoke comes back.Checked fuel filter and found fuel was black inside the filter,so replaced the filter and air filter but still the same.then had a master tech check it over he found the diaphragm in the vaccum actuator for the inlet manifold not holding vaccum so replaced this and still the sameAnyone with any help would be greatly appreciated
audi a4 2.0TDI BRD engine thick black smoke and loss of power under load
- Thread starter kmitch93
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BRD will be a pre 2008 A4: B7 chassis not 8K.
Do a search for A4 B7 oil pump recall / issue. Has he checked his oil level regularly? Sounds like he could be burning quite a bit on those hills. Did this master tech not know about the oil pump issue or did he say it couldn't be related?
No bother thanks.yeah he said it would have been blue smoke so he knew it wasnt that.its just had the injectors and turbo replaced less than 6 months ago.hesbeen checking oil level which is ok but hes not long bought the car and the DPF has been removed,could this be part of the cause
Audi Dynamik
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Black smoke at low revs and when the engine labours sounds like it's over fuelling. Did he buy the car after the injectors and and turbo were changed? Has he seen the receipts? Any idea why this was needed - wrong fuel at some point?
What are the fuel consumption figures like? If he's getting well below normal I'd look at quite a few things. Also is it running rough? Start with a VCDS scan and look for faults - inlet manifold flap, MAF, throttle faults etc.
Yeah its a b7,didnt realise it was the wrong thread.yes definetly over fuelling as consumption is well below average.bought the car after they got replaced supposidly was a recall and has all the reciepts.carried out a diagnostic check which didnt show any faults.tried unplugging the MAF sensor and took a drive yet still the same also cleaned throttle body and inlet manifold.once the turbo boosts it runs fine until you come to a steep hill and loses power.car runs fine at idle.what we did notice is that when we removed the inlet manifold the spring on the flaps was quite weak.
Look for evidence of one of those cheap and nasty resistors in a box. Cold the previous owner have fitted one somewhere?
What do you mean nasty resistor?lol.forgot to mention the car has also been remapped,heard this can cause problems if not done properly
Unless you can guarantee the map had been done properly, there is no point going any further until it's put back to standard or verified that it is not the problem. What you describe is a symptom of a poor remap which just increases the injector duration. I would also suggest MAF, but if unplugged it still smokes heavily then It probably isn't. I can look at it, but we are in Stockport.
Rick
Rick
Resistor in a box is a nasty cheap 'remap' that pushes more BHP by over fuelling. However, the key bit of info is remap. A bad remap can cause exactly what you describe. As Rick says you have to put it back to the factory map to prove the entire engine is AOK before you go any further.
This is a complete guess but I'm thinking previous owner wanted more grunt, fitted a cheap resistor type 'remap' box that over fuelled so badly that over time the turbo and injectors failed. These were replaced. The resistor just fools the ecu into delivering way more fuel than is required. If that's true it's likely the remap that replaced the box was the cheapest one available and it's working in a similar way.
Think of all that black smoke and soot. The bit you see puffing out the pipe is the bit that escapes - where is the rest? It's clogging every pipe from the outlet manifold to the tail pipe and every nook and cranny in between. To achieve that mess is costing loads in extra diesel.
I'd put it back to stock ASAP before you get into that costly cycle of hideous expense of replacing components that are being pushed beyond factory spec to failure. You're burning a lot of diesel for a negative result and that's just just wasted cash that could go towards a really good remap.
Think of all that black smoke and soot. The bit you see puffing out the pipe is the bit that escapes - where is the rest? It's clogging every pipe from the outlet manifold to the tail pipe and every nook and cranny in between. To achieve that mess is costing loads in extra diesel.
I'd put it back to stock ASAP before you get into that costly cycle of hideous expense of replacing components that are being pushed beyond factory spec to failure. You're burning a lot of diesel for a negative result and that's just just wasted cash that could go towards a really good remap.
Chances are the DPF removal and remap were done by the same cowboy. I have to agree with Johnnythepie, removing a DPF badly could have a catastrophic effect on a turbo diesel engine. Chopping out the DPF will cause the back pressure to drop and the result would/could be loss of low rev torque. That's a symptom you've got. To bring that back pressure back (bp is not exactly a good thing in theory but the engine was designed and balanced for an exhaust system with some back pressure) you would have to change the fuelling curve to compensate for the losses. Do that wrong and you get excessive over fuelling with lots of soot and smoke. You've got that too.
Everything from the air intake manifold to the tail pipe could be out of whack with turbo, cat, and manifold temperatures way over spec and the pressures and flow all over the place. Is the exhaust pretty noisy under load? That's another DPF / back pressure effect - it quietens things down a bit.
I'd get the car to someone with VCDS, preferably a good remap place, and get them to run measuring blocks to get an idea of the values to see what can be done to get the whole system flow and pressures correct and the fuelling sorted out.
Everything from the air intake manifold to the tail pipe could be out of whack with turbo, cat, and manifold temperatures way over spec and the pressures and flow all over the place. Is the exhaust pretty noisy under load? That's another DPF / back pressure effect - it quietens things down a bit.
I'd get the car to someone with VCDS, preferably a good remap place, and get them to run measuring blocks to get an idea of the values to see what can be done to get the whole system flow and pressures correct and the fuelling sorted out.
Please note that the boost from the turbo through the intercooler until the intake needs to be checked properly
What was the solution? I have the exact same problem, and are about to buy a new turbo - even though i doubt the turbo is faulty
