Afternoon folks,

 

I’m in dire need of some help to try and get to the bottom of this issue.

 

Right so I bought my mk1 vrs a couple months ago, has a cat back exhaust, cone filter and mapped stage 1. However the boost is surging, on WOT it goes to 22psi and then drops back to like 17-18 then begins to fluctuate between 17-22 then down to like 13-15 and back up, just keeps doing this through the mid range. I’ve tried 2 different n75 valves, unplugged the maf, tried a different diverter valve and nothing seems to fix it. No engine management lights so I’m guessing it won’t be spark plugs or coil packs, honestly clueless as to what’s going on, can’t hear any boost leaks.

 

it seems to be very common in these 1.8T engines so has anyone else had this and managed to fix it? I’m totally clueless 🤦🏻‍♂️

I'd be looking at the ECU map. Any proof of who has done it? Is it a generic slap on map? If you can get access to an original or someone that might have a deimmobilised ECU and try that.

I had a similar issue with my 1.9 TDI Alh 66Kw
Try cleaning the MAP sensor which sits on the intercooler...doing this solved the issue for me.