I purchased an e39 530d April this year. 185k on the clock. It was burning oil and put it down to valve seals. It also became apparent that there was what im going to describe as a misfire. When I revved the vehicle stationary or whilst driving to around 3-4k, when the revs came back down the vehicle would start juddering as it were about to stall. At this stage it never did stall. As well as this, the vehocle/engine shakes noticeably at around 1500-2000rpm.
I had the car in a workshop, all work carried out by myself. Apart from when I had the head skimmed and valve guides checked. It had new valve seals, new head gasket of course. I did the main vacuum lines (didn't do short one to turbo as wasn't faulty). It was timed and double checked to make sure.
I got it all back together and no more smoke and at the time it no longer mifired. I think it was around two weeks it ran absolutely fine in terms of smoke and misfire. It still juddered at 1500 - 2000rpm.
A couple of weeks ago, maybe 3 it trted to misfire on the rare occasion. It won't misfire if just left to idle, it is worse when cold/first started. It will only do it whilst boosting when you get to around 3000rpm. When this happens, I lose more or less all power. A good amount of white/grey smoke is very visible as well especially when trying to keep the revs back up. I can get it to do it whilst stationary but works slightly different. When I rev to 3 or 4k, when the revs come down to idle it will start juddering. It would even stall quite often. Also will add that it smokes when at high boost 3k+. This could be normal as egr has been delrted and its a dirty old 3L!
No codes at all have appeared. I have tried many different scanners even a delphi. The only one I haven't tried is Inpa.
I suspected fuel. I thought low pressure when at high revs. I've monitored data whilst it was misfiring and couldn't really notice anything change. I did a leak off test, I replaced the worst Injector but no difference.
Someone I work with had the idea of clamping the vacuum pipe the goes to the turbo solenoid as he thinks fuel is fine. When this pipe is clamped, I have no boost but it won't misfire no matter how hard I try. The judder at the certain revs also disappears. Today I swapped the solenoid with egr one. The fault didn't clear and when the same vacuum pipe is clamped, it now doesn't stop the rev shake at 1500rpm. Does this suggest that both solenoid are faulty?
I then took the pipe of the turbo inlet side before compressor. There is a fair bit of play and plenty of oil being passed. Waste gate is also very squeaky and can be heard when ignition switched on nd off. Turbo seems faulty but would this cause a misfire like this?
Additional info is that the car has receipts for 2 injectors and a high pressure pump. I can't guarantee they have been fitted of course as pump doesn't look clean really, in fact looks quite greasy from either diesel (not a drip leak) or from oil.
The car is also said to have been remapped but no proof. Not sure if this was used as a selling point or is the truth. I have wondered whether this could be a dodgy map.
I think that's all I've got to say! Any questions please ask.
I'll take any suggestions.
Thank you very much if you read this far!