u/Impressive_Assist219

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CBEA

160k miles

Whitbread disaster prevention.

Stage 2 Mrtuning

Car was for sale. Had a potential buyer come. Knowledgable guy came with VCDS as one should. Went for a test drive and claimed fuel rail pressure code at half throttle. Pulled hose off the whitbread filter and said glitter. I looked and maybe saw something. Couldn't tell really. Looked kinda like flashlight reflecting off diesel on a few of the screen openings.

I took it for a drive and got 1800 bar requested and actual driving much harder than I usually do. I can't recreate a low rail pressure code.

Got me thinking though. At every filter change for the last 6 years I would see a few flakes of what looks like metal kinda floating on top of the oem fuel filter. Just thought it was normal. I mean it's been the same for 120k miles. The past few changes I've been evacuating and wiping the filter housing.

I'm not buying cp4 failure but it got me thinking... Does anyone change the whitbread filter. They don't sell replacements on their site.

Like many cars this one cuts alternator voltage for better fuel economy during low load events.

The problem I'm having is the voltage is dropping when I accelerate. Watching live data it goes from 14ish to 12 ish at half throttle or more. Let off and 14v's returns. It's noticeable with the headlights on and you can hear the hvac fan slow down.

There is a single wire on the side which I assume is either commanding the nator or sending data. Unplugged I get 14ish v's all the time.

My question is WTF. Well what is the process it uses to drop voltage. Is there a module somewhere that could be replaced? A little research points to this black box right off the negative terminal but I can't find anyone else with the same issue.