Rally: the original motorsport
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Photo Courtesy of Warwick Patterson
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Bypass or Calibrate the overboost switch on LH 2.2 cars

The switch is located in the dashboard, driver’s side, just above the APC transducer.

To bypass it, just remove the vacuum hose from it and plug the line that went to it, or follow the vacuum line to the T fitting and insert a straight vacuum connector where the T fitting was.
You can also Calibrate the switch if you want to retain this safety switch. I had mine calibrated to somewhere right around 25 PSI. To do this you will need to remove the switch, it's clipped in place at the back of the switch. Once removed hook up a pressure tester to the vacuum port and a multimeter to the 2 connectors that have continuity. pump the switch up to 15psi and you should see the connectors loose continuity. There is a set screw in the middle of the switch, covered in red loctite type compound. Scrape the compund out to expose the flathead screw and turn the screw to set it to the new tripping limit. Use the pump to test your new limit. Once done you must reseal the screw by pouring red loctite in the cavity.

Bypass the overboost switch on LH 2.4 cars

This is done at the LH ECU.

You'll have to remove the carpet trim pieces by the door in the passenger footwell to peel the carpet back and gain access to the LH ECU. It is bolted to the sheetmetal on the righthand side of the passenger footwell.

Locate the system and fuel pump relays by the LH box, you'll see two brown&white wires each with a single-pin connector on the end. Disconnect them and connect them to each other and you'll have bypassed the overboost.

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