Does anyone know what this turbo is good for?
It's standard equipment on my Audi A4 1.9 TDI (B6). I've had the car chipped to just under 180BHP and 450NM. Boost requested is at 1.4 bar and the limit was raised to 1.6 bar after constant overboost issues causing limp mode in high gears. However the car still overboosts, just under heavier load / high speeds / bigger hills. Always seems tyo be in 6th gear after 3,000rpm with some level of gradient involved.
I've replaced the vacuum hoses, intercooler pipe, egr valve (serious leaking) to no avail. I've now also replaced the turbo with a low mileage one (full actuator movement, very clean and no play in the shaft), which seemed fine at first (4 weeks ago) and on the long journies at that time. However overboost is now back bringing in the limp mode. VAG-COM group 011 shows the N75 cycling the actuator fully. Sometimes there is no fault code and other times there is the 17965 - Charge Pressure Control: Positive Deviation P1557 - 35-00 - - code.
I'm running out of ideas now and wondering if the the power or torque is genuinely too high for the turbo. Or perhaps there is a sensor somewhere that the power or torque are exceeds it's limit. Or that my car just really doesn't like the ever growing short journies followed by fast roads.
Any ideas would be greatly appreciated, as I'm now out of them!
It's standard equipment on my Audi A4 1.9 TDI (B6). I've had the car chipped to just under 180BHP and 450NM. Boost requested is at 1.4 bar and the limit was raised to 1.6 bar after constant overboost issues causing limp mode in high gears. However the car still overboosts, just under heavier load / high speeds / bigger hills. Always seems tyo be in 6th gear after 3,000rpm with some level of gradient involved.
I've replaced the vacuum hoses, intercooler pipe, egr valve (serious leaking) to no avail. I've now also replaced the turbo with a low mileage one (full actuator movement, very clean and no play in the shaft), which seemed fine at first (4 weeks ago) and on the long journies at that time. However overboost is now back bringing in the limp mode. VAG-COM group 011 shows the N75 cycling the actuator fully. Sometimes there is no fault code and other times there is the 17965 - Charge Pressure Control: Positive Deviation P1557 - 35-00 - - code.
I'm running out of ideas now and wondering if the the power or torque is genuinely too high for the turbo. Or perhaps there is a sensor somewhere that the power or torque are exceeds it's limit. Or that my car just really doesn't like the ever growing short journies followed by fast roads.
Any ideas would be greatly appreciated, as I'm now out of them!