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Discussion Starter · #1 · (Edited)
Every time I drive it goes into limp mode
I turn on and off and it will boost away till the usual 80 mph and go dead and stay dead

Car Details
Auto/tip 97k miles
New turbo 20k ago
City car all it's life

Rough ideal but not missing and goes out of it


4521 fault code (boost control high)
Glow plugs x 4 fault with controll unit. Prob the miss!

What I've done so far

Replaced vac line, no change
Maf meter replaced, no change
Disconnected map sensor, worse
Cleaned shit outa map sensor, no change
Cleaned egr, no change
Swapped egr solenoid with turbo one, no change
Removed swirl flaps.
Rail pressure 320bar idle
Turbo diaphragm working

Smooth running test shows cyl1 -82.30mg/stroke
The rest don't read any thing

Compared with e90 it read all around the same at .3 mg/stroke.

Leak of test shows all other 3 cylinders are double why cylinder one is.
Last owner claims he replaced one injector but can't remember which.
Any ideas?

Read with Delphi

*^updated
 

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Did you do an actuation test on the wastegate? Im guessing yours is the M47N Euro 4, if so it will have an electronic actuator on the turbo.

Also are you getting a DDE light when it hits limp?
 

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Discussion Starter · #3 ·
Did you do an actuation test on the wastegate? Im guessing yours is the M47N Euro 4, if so it will have an electronic actuator on the turbo.

Also are you getting a DDE light when it hits limp?
Irish car man, it has vacum actuated turbo which is why I tried switching solenoids.

No lights on dash at all

Starts grand but small bit lumpy for a few seconds

When it hits limp mode, I get the 4521 fault code.
 

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Have you done manual actuation test? Also have you inspected the turbo impeller for signs of soot?
 

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Discussion Starter · #5 ·
Have you done manual actuation test? Also have you inspected the turbo impeller for signs of soot?
Actuation test when the ignition is turned on is it?

Check for soot on the intake turbine or remove turbo and check vanes?
 

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Actuation test when the engine is running, the vacuum actuator should operate (rod extends) when you get the revs up a bit. I guess it could be done with the engine switched off but you would need a vacuum pump.

As for inspecting the turbo, it sounds a bit like sticking vanes, Ive seen turbo coked up with carbon and stick a bit.

There is also a pressure converter down alongside the turbo, check the hoses for splits and maybe swap it out to check it,
 

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Discussion Starter · #7 ·
Actuation test when the engine is running, the vacuum actuator should operate (rod extends) when you get the revs up a bit. I guess it could be done with the engine switched off but you would need a vacuum pump.

As for inspecting the turbo, it sounds a bit like sticking vanes, Ive seen turbo coked up with carbon and stick a bit.

There is also a pressure converter down alongside the turbo, check the hoses for splits and maybe swap it out to check it,
All vacum lines changed, I switched 'p.c.' With egr one, no change,
When it's running and I remove vac line to turbo the rod moves
 

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Any obvious signs of dirt or oil when you take off the intake pipe to the turbo?
 

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Discussion Starter · #14 ·
Found fkd o ring on inter cooler, just put a normal oring on for now.

Seems that every time I clean injectors it runs good but then after an hour starts goin to limp mode agin
 

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My 320d had a rough idle and had a flat spot up the rev range. i changed everything and almost went crazy. in the finish i cleaned the filters on the pressure converters with carb cleaner and it sorted all my problems, well car ones anyway!
 
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