Thread: TD5 black smoke under high rpm

Hi Guys. looking for advice on why my manual TD5 is laying a black smoke screen at high RPMs. I've never really taken it over about 3000 in the course of regular driving and not had any issues related to smoke. Recently, I have run the motor to near redline both in neutral and under hard acceleration on the road and in both cases, the car starts to leave a black smokescreen behind it as soon as somewhere between 3500 and 4000 RPM is reached.

I have got a clean air filter, have replaced the induction hoses with silicon, have flushed out the intercooler and have deleted the EGR, all of which were done prior before I noticed this smoke issue. I did/do have a problem with very poor acceleration at low, pre turbo boost, RPMs (to the point where driving an empty tipper truck felt like driving a racing car) and I have improved this by cleaning the MAP and the pre air filter sensor (whatever that is called), however the black smoke problem was present prior to this. On the power side, I still feel the car is still a little under powered.

I'm suspecting maybe a turbo wastegate issue? Any other possibilities? Cheers.

Originally Posted by shack

Do you have access to any logging equipment?

Yes, I have a Nanocom and went for a run today with it logging. It was actually the second run, because I discovered that switching screens after starting the recording silently stops the recording . I also discovered even earlier that there are little blue plastic inserts in a Nanocom that can fall out during manufacture and lodge in the SD internals, causing an inserted SD card to derail and vanish into the guts of the device

Originally Posted by laney

Have you given the MAF a clean pull the heat shield of the turbo disconnect the vacuum arm from the waste gate a see if it if free moving I loosened mine with wd40 silicon spray. If this doesn't work then maybe get your injectors checked hope this helps.

The MAF is a relative new cheapy which doesn't compare too badly with the expected values. It did give some 0 readings at high revs for a few cycles though. Not sure if this is a Nancom logging issue or a serves-me-right for buying cheap! I try with the MAF disconnected and noticed smoke, but the breeze had piped up by then so it's hard to compare the amount of smoke to the earlier session. It looked like it may have been less. I hadn't thought to much about injectors as the impression I get is that they last forever, but that would make a sense. Is there a test for these?

Originally Posted by PhilipA

Have a look to see if you have a collapsed boost hose from turbo to intercooler or intercooler to inlet manifold.
Maybe it only collapses under high boost.
Regards PhilipA

Originally Posted by shack

If it is an intercooler hose, they tend to delaminate internally, they can seem ok...

And I know you're thinking to yourself that boost pressure should hold the internal lining "out" shouldn't it... Guess again.

The original hoses were pretty ordinary and I replaced all the hoses with new silicon hoses a few months back and these appear reasonably well made (I read the advice on this forum about issues and made sure I ordered decently spec'd ones). I did notice that the hose connected to the turbo outlet has been moving slightly, but all the hose clamps needed a slight nip up. The hoses themselves look fine from the outside. I suppose I could set up an old go-pro and see what is happening under load to them. I'd imagine they'd either suck in due to venturi effect or bulge out with internal delamination?

I did have one of the original hoses "pop off" at on stage and the power loss was dramatic, with the old girl struggling to reach 80 (kph). I'm not getting that same or even a seat-of-the-pants feel of power loss, but then again I don't have another TD5 to compare to.

if anyone is interested, I've attached a modified log from the Nanocom which comprised a run around the block with a couple of high RPM squirts and foot flat to the floor low RPM accelerations when going around corners in either second or third. Not too sure what to make of the values.