Cold Air Feed Induction Kits K&N Type

[Laird Scooby]

Originally Posted by Dirty Rooster

Thanks for your explanation of the O2 sensor, stuff I didn't know.

Now ;

I've had two turbo engines (in the same car) both bog-standard, and found them to accelerate slightly better under part-throttle than wide-open (2nd to 4th gear, not from standing), am I imagining this or could it be mixture?

You're welcome, it could be mixture, dirty injectors, weak fuel pressure regulator, plugs (gap too large and/or wrong plugs), timing (cam and/or ignition including any advance tube it may have - don't know the year of the car/engine so just throwing several possibles in), partially blocked exhaust or air intake - the list goes on.
Could also be a weak wastegate/actuator on the turbo, only way of knowing is to go through everything methodically starting with all the basics.

[mhuk]

Interesting... weak wastegate/actuator on the turbo,

I was messing with the actuator. I have a 19T. I wonder if it's jamming up on return. It boosts fine though

[Laird Scooby]

Originally Posted by mhuk

Interesting... weak wastegate/actuator on the turbo,

I was messing with the actuator. I have a 19T. I wonder if it's jamming up on return. It boosts fine though

My line of thought is on part throttle it doesn't build boost as quickly (in theory) allowing the available boost to accelerate you quicker. On full throttle the theory is it builds boost quicker so it could be operating the wastegate early allowing boost to drop.

If you've been fiddling with the actuator and adjusted it, it's possible you went the wrong way if you were trying to increase boost.