This transporter originally came to me after having a foreign object dropped into the inlet manifold causing damage to cylinder 1. I have rebuilt the engine (piston, valves, guides etc) and the turbo was sent for inspection and consequently repair due to impact damage.
Since covering around 2,000 miles it has started suffering from underboost P0299. I have done all the obvious checks, vacuumed everything, smoked it, pressure tested intercooler and hoses and the boost control solenoid was replaced at time of rebuild due to being noisy. I have also tested egr and even tried blanking it but made no difference. when reading live data the actual boost is lower than the desired boost yet vacuum is being bled off from the actuator via the boost control solenoid. I have tried it up the road with a vacuum gauge T'd into the actuator and I start off with approx 15hg of vacuum before it slowly decreases and I can cause an overboost condition by manually increasing vacuum.
Any help with fixing this will be greatly appreciated.

The second image live is live data where it went straight into limp mode under acceleration 6th gear approx 2,000 rpm.

Hi

Just a thought, have you check vacuum before control valve is being maintained when fault occurs?

You say it has done approx 2000 miles, was it OK to start with |(or possible masked by gentle driving)? just thinking of possible vac piping error as its been to bits.

Aidan

Hi Aidan,
Thanks for your reply. Vacuum remains constant at around 20hg before the control valve and is stable as limp mode is triggered. I tend to agree that it was most likely masked by gentle driving initially as I can only get it to occur under high load at relatively low rpm. The customer did mention that it had gone into limp mode prior to the initial damage but had never had the faults read so it is possible the fault existed prior to this. I have checked that all the vac pipes are routed correctly and I'm confident they are.

Hi

Does this have a position sensor on the vacuum capsule on turbo ? i suspect it is to old but if it does there is a critical setting procedure

No this is just a straight forward vacuum capsule.
I have messed around with this quite a bit now, checked exhaust back pressure, fuel delivery rate, air mass, boost pressure sensor, temp readings, and I've pretty much exhausted my knowledge and I'm out of ideas. I've even started from scratch with the basics and gone back through it as a fresh job just be 100% I've not overlooked something simple. I now have the turbo back off it to be returned today to be checked again.

Tony, did you find out what was causing the problem? Have exactly the same with a van i have in now..

Regards

Martyn