So, recently purchased a Mk1 Vrs. Issue I'm having is at about 2800/3000 RPM the whole way up the rev range in every gear (apart from 1st) at WOT the car is lagging. It's hard to describe but it's like it lags, then it's fine, then it lags again and so on. Now, if I part throttle it, it doesn't do it. 

I've a attached a log logging boost (actual vs requested), also logging N75 duty cycle & also MAF. Third gear, WOT, 2000RPM to 5500RPM. Car is mapped, by who I don't know. Was it Dyno'd? I doubt it. Car is standard other than the map. 

In my mind I've ruled out the N75 as it seems to be trying to do it's job in the logs, MAF reading is a little strange being that it's reading a little high at spots but I've unplugged it and it makes no difference. I've checked the wastegate, it's not seized & moves freely. I've also done a log logging misfires (there are none). Anyone any ideas? 

I'm really starting to think it's the map but a couple of previous owners said the car ran well when they owned it. 

Second picture is the log. First is just so you know what's being logged. 

Oh forgot to add. Car was recently smoke tested for boost leaks & there are none. But I'm going to do it again tomorrow for peace of mind. I like to do things twice just to be sure 😂

I'm having the exact same issue. Hope someone can help! 🤞

Four new Bosch coil packs cured my issues! Is the car mapped? What happened mine was whoever tuned the car turned off the misfire recognition counter so when I was logging misfires they weren't showing up (disabled) (I didn't notice). It was only after I'd logged everything else and found no issues that I decided to double check the misfire counter again and I noticed they were disabled and I couldn't get them to enable. I knew then it was 100% a coil. Obviously couldn't check which one so replaced all four. Genuine Bosch. Running perfectly now.

Ahh okay, guess i'll change them next then! It's not mapped yet... but am planning on it as it's got a piper exhaust with sports cat, and its had new over the last year: MAF, N75, diverter valve, fuel filter, pipercross panel filter

 

Would you change the spark plugs as well at the same time? it only had new plugs about a year ago..

I'd change the plugs as well yeah. They don't cost much. Also if you've someone with VCDS do some logging so you can find out for sure what the issue is instead of just replacing parts and hoping it solves the issue. If you've nobody with VCDS I'm sure there's somebody close to you on here with it. Where you based?

yeah fair point, i'm in Bedfordshire - near Milton Keynes