Losing turbo boost

[andrewkatz]

Hi All

I have an ML420 W164 V8 Diesel (2008). I have in the past had a (very) occasional problem with losing turbo boost after the car has been idling for a while. If I restart the car, the problem immediately disappears.

However, this happened again yesterday, but this time two or three restarts didn't fix it (and trying to drive on the motorway without any turbo is not much fun). I tried the car again this morning, and the turbo is back working again. No check engine lights.

I ran my scanner (iCarSoft) and it's showing error 2598-001 Check component Y27/9 EGR Positioner). Positioner Signals Fault. Is this the relevant fault for the problem?

Also, does anyone know the usual maximum boost for this engine? My scanner is (now) showing 32psi total pressure (i.e. about 17psi boost over ambient). At idle it's about 17psi (i.e. boost of about 2psi).

Thanks in advance!


Andrew

 

[M80]

I would start by removing the EGR and checking it has free movement.
I've cleaned a couple up and then soaked the moving parts in plusgas overnight, working the moving parts so the plusgas can penetrate. That restored them from being tight.

 

[Uncle Benz]

The egr valves used to be common for trouble with these, and give the symptoms you describe. There are two of them, top of the engine, at the back. Be sitting down when they quote you.