Thanks for the reply.
Am confident that the turbo is okay. It's original OEM direct from Garrett and not a reconditioned unit. It spools up (can hear it), there is no free play in the shaft. At idle, the variable vane actuator arm is pulled down into the vacuum pot, so it appears to be working - full throttle in 2nd gear puts me back into the seat. Checked the thread count on the actuator against your photo and the setting seems correct (I know they are bench calibrated before being shipped).
It's looking more and more that it's one of two things:
2. Charge air piping related
The EGR system on these cars is a little complicated. The boost pressure sensor is used to drive the VNT actuator demand, and the mass airflow sensor controls the EGR valve actuator demand. However, the system is not a closed loop and is operated using a mapping based on engine speed, fuelling, VNT and EGR valve duty cycles. Bit of a bugger to troubleshoot.
Thinking that the EGR is sitting open due to soot build-up. If acceleration is related to fresh air intake and efficient fuel burn, if the EGR is leaking under heavy acceleration it will feel like a lag in engine torque production.
Going to first try cleaning the boost pressure sensor, then I'll remove and clean the EGR and see what happens. Have noticed a slight buzzing noise coming from the EGR valve area so the EGR could be on it's way out. Happens if I blip the throttle. RPMs go up as then as they start to fall I hear a distinct "bzzzzzzzzzz" noise for about 1 second.
Have been ignoring it because I think the EGR has a copy position sensor, but have discovered that it might only throw a code if the deviation between the position and copy sensor exceeds 15%.
Will give it a go with the EGR cleaning and see what happens.
Originally Posted by Green-chameleon View Post
that sounds very much like the start of mine
you couldn't hear any leak standing in front of engine while being revved but under load as you was driving, i even jacked it up and went through gears couldn't hear it. was only while road wheels had weight n driving.
this seemed ok in low gears and was only because my son said should be faster that i thought issue.
mine showed up codes as prev post.
really does sound like air/leak issue
see if local garage has a rolling road or an mot centre with some rollers