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chicaneuk

Slow to boost, grey smoke..

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In the last few weeks I noticed my 530d is now taking up to around 3,000RPM to come on boost. Feels lively enough when it does but it’s accompanied by a lot (like road filling amounts) of grey smoke out of the exhaust. Car also stinks of diesel too, moreso than normal, if you get on the power much. 

 

Having owned the car a couple of years I have worked through a number of the issues and changed all the vacuum lines and replaced the MAP sensor and replacing the pressure converter valves under the manifold.. my gut feeling this isn’t a vacuum line again but is more likely to be down to the MAP going (it was a genuine BMW part albeit second hand) .. just wonder what other common reasons might be to blame before having to get INPA involved to try work out what is going on? 

 

Thanks. 

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First look if the turbo vacuum actuation is working at all. When engine is started the rod on vacuum bell should pull the VNT vanes closed. You can see this from above with some lighting.

Edited by Clavurion

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Yep have done that check in the past @Clavurion so will see what’s happening there.

 

@duncan-uk I am fairly sure I managed to change every vacuum line when I replaced them all including to the engine mounts.. so hoping they are not the issue even though all symptoms point to it being that classic problem. 

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Was struggling to see whether the VNT rod was moving.. can get adequate lighting and visibility of it no problem, but no spare hands to start the car for me, so I can watch it. I did swap the spare MAP sensor that I have (which I know is good) and pulled and capped off the vac line that runs down to the engine mounts but that didn't make any difference to how it drives at all, so need to check again the VNT rod as mentioned when I can get a friend to help :) (there's not even a convenient place / ledge down that side to prop a camera phone to film it... I did try!) 

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OK got a mate to help out and he fired up the car.. sure enough the VNT actuator didn't move at all. Curious! 

 

I pulled the vacuum line going to the reservoir and despite being only replaced < 2 years ago, it'd gotten brittle and split at the end and just fell off. But putting my finger over the end and revving the engine I Couldn't feel any vacuum at all so the problem feels like it's further up stream somehow. I followed the line along up to the little distribution unit under the manifold and it all seemed fine there but I guess I need to check if there's vacuum even going into that.. if not I guess it could mean the pressure convertor valve under the manifold could have died / failed? 

 

More time needed for dismantling and troubleshooting than I have at the moment so hoping the car can keep limping along with low power for another week or two until I can find some time to look into what's going on but obviously any thoughts or likely candidates for the problem, I am all ears :) 

Edited by chicaneuk

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The vacuum solenoid for turbo is after vacuum reservoir near turbo. The solenoid under intake manifold you are talking about is likely the one for EGR valve. If there is no vacuum on the distribution piece on that connector going to turbo it's likely clogged by a part of perished tube. On the connector piece there is a narrow surge. First try to suck it open and if needed try a needle or similar.

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Or you can remove other hoses on the connection piece if other connections have normal suction. Then put swirl flap or EGR hose on the clogged one and use a one functioning normally for turbo. Just bear in mind that the tallest connector has the largest bore hole and is reserved for engine mounts.

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