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Checking & adjusting boost pressure


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MEASURING BOOST PRESSURE

This measurement requires the following road test conditions

  • Engine at normal operating temp (make sure oil is warm along with coolant)
  • In 3rd gear, hold the car between 1500rpm and 2000rpm
  • Floor the accelerator pedal
  • Monitor the boost pressure between 3000 and 4000rpm, note the pressure, and compare to the chart below (the factory manual calls for measurement at 3k rpm which is too low for old turbo charging units IMO)

N9T: 610 +/- 40 mbar (8.8 +/- 0.6 psi)

N9TE: 620 +/- 40 mbar (9 +/- 0.6 psi)

N9TEA: 780 +/- 20mbar (11.3 +/- 0.3 psi)

N9TEA - CHECKING OPERATION

  • Disconnect the connector from the electro valve
  • Install boost pressure test gauge
  • Perform test (same test above for checking boost pressure)
  • Record values obtained as P1 (manual says ~0.5bar or ~7.25psi)
  • Reconnect the electrovalve connector
  • Perform test for boost pressure again
  • Record new values obtained as P2 (manual says ~0.8bar or ~11.6psi)

--> If P2 > P1 -- boost monitoring is correct

--> if P2 is the same as P1 -- boost pressure monitoring is incorrect

If boost pressure monitoring is incorrect, check:

  • Check continuity of wires 2 and 2D
  • Check diode (wires 2A - 2C) between pins 1 and 2 of electrovalve
  • Check the hoses and circuit taps within the hose routing for: dirt, oil build up, ice at the restrictors

Scans of these pages in the manual will be attached shortly....

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