Now this ones got me stumped.
I have a tddi mk6 100bhp with an occasional power loss problem. Basically at the start of a journey its got plenty of power and pulls well through all gears but after a few miles it goes gutless, it's hard to explain but the best way I can is when you put your foot down in low gears the turbo is none existent. It gets to the point where the turbo should spall up (which it does) but there's no power or at least no where near the amount it should have. Some times it runs perfect throughout the entire journey but that is rare. It hasn't really bothered me until the past few weeks as the van is usually kept relatively empty or carrys light loads but I was carrying a load the other week and it was painfully slow, it wasn't a massive weight but it would only get 40mph up slip roads and I was lucky to see 70mph on the motorway. Overtaking lorries was impossible unless down hill.
I was convinced it was the egr valve at the weekend after repeatedly pulling over and unplugging the vacuum pipe and sensor when I had full power to notice it went gutless (I did it three times whilst driving the same journey). Yesterday I made up a blanking plate and blanked it off but after this morning its clear that it hasn't done anything. I left home with full power, got on the motorway with full power, then as I came off there was no traffic I tried it and yep it was gutless again.
The only thing I can think of is gunk and crap in the intakes as I haven't cleaned it out yet but I would that give intermittent power loss? An air flow sensor buggered or gunked up? Or a iffy fuel pump? Apart from this the van runs sweet as a nut, no strange noises, no error lights, no lumpy running and starts on the key.
I appreciate this may sound like it's me getting complacent with the performance throughout the journey but it's not lol.