Hi All, My car has a YB Engine fitted, it has 8 greens and a T4 turbo.
I have had the car on the rollers whilst I have owned it a it put out a true 330BHP with 1.8 bar boost. The engine has gradually lost boost but during the last month it was only boosting 0.5 bar and running like a dog. I traced the rough running to a faulty water temp sender and this is now sorted. The problem I have now is I think the actuator is not opening at all when driven due to the low boost, could it be the wastegate is being forced open by the exhaust due to a weak spring. I have wound the actuator arm shut so that it opens with 1.5 bar static pressure via a compressor but I am still only getting 0.8 bar max when driven, it does not take much effort to open the wastegate manually with a pair of grips with everything connected. Is it the actuator that is faulty before I replace it. Also will I run the risk of overfuelling if the boost is to low on full throttle.
Thanks in advance Pete.

 

Pete, slightly off topic mate, only 330bhp on 8 greens/T4 and nearly 2 bar of boost?? never right surely??

Could be an Actuator problem i'd say..

 

The engine has been de-tuned by extending the actuator rod to save my gearbox by the previous owner. Apparently it put out 505BHP & was running over 2.3 bar on the rollers before I owned the car but the gearbox only lasted 7 miles!!!!
This is only what I was told so can't confirm 100%.
It was also apparently live mapped by Ahmed Bayjoo and I have no reason to doubt this because it usually drives sweet as a nut.

 

T4 at 1.8 bar is a lot more than 330, unless that is at the wheels ?
tbh the best thing you could do is get it on the rollers, could spend more just guessing at the problem in the long run, if a duff actuator as it sounds this will stand out a mile and be fixed at same time.
tabetha