spent 5 hours on the car this afternoon...
First stripped the Inlet assy down, bearing in mind i cleaned the EGR valve around 5k miles ago it was in a terrible state again today:
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Now that the valve is fixed closed I cleaned it all back to shiny bare metal again and fitted an ally blanking plate I made from 1.2mm sheet along with another gasket.
I then got the inlet manifold off and as expected it was badly caked in black sludge, over 5mm thick in places! My chosen cleaning method was to scrape out the big chunks and then fill with oven cleaner, leave for 10 mins and then thoroughly blast the innards with a power hose... after 2 rounds the insides were silver again and the switching valves shiny and free to move fully. I also fitted a new actuator even though mine worked fine as they are such a cheap part l.
While the inlet assy was off I also got the oven cleaner down the ports and have them a thorough clean as they were equally caked in thick carbon build up.
I also cleaned the intercooler top hose hose and looked at taking the cooler off to clean it internally but it looks like the bumper and grille need removing to access so have it a miss.
Then I went around the other side if the engine and removed the air box to get access to the turbo. Again the VNT felt fine but I removed the bung out of the turbine housing and filled it with oven cleaner.
While I was doing this i noticed a load of soot around the cooler, turns out the integral pipe between turbo and EGR cooler is leaking where the flange is brazed onto the pipe. I took it off and double checked and the gasket is fine so definitely the pipe, this certainly won't help the low down torque and may be contributing to the flat spot, so now that the EGR is disabled I'm going to make a stainless blank and blank the pipe off right where the EGR leaves the manifold, having looked at the system I'd recommend doing this anyway if you have EGR mapped out as any additional volume (ie pipe between turbo and cooler) will slow down turbo spool-up and this will be even worse if the pipe leaks like mine.
(Pic shows leaking flange)
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I didn't have time to make a blanking plate today so built everything back up with new gaskets where required and tested it.
Unfortunately the flat spot is still there but definitely lesser and the car seems to drive much more smoothly, especially when accelerating, power is much more progressively delivered and less smoke for sure.
If I can find some stainless sheet ill finish the job by blacking the EGR off at the cooler tomorrow and that is pretty much all I will do now other than run another tank with BG244 now it's EGR and sludge free...