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The mkiv Supra Owners Club

Fuel Cut

Ian C

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Fuel Cut


Also known as:

Boost cut


What is it?

Your car pulls strongly and then loses all power like you've lifted completely off the accelerator. The Malfunction Warning light on the dash (red exclamation mark) lights up for a couple of seconds, and then you get power back.


Usually caused by:

The stock Supra is set up to see 0.8bar of boost. The ECU has a failsafe system in it to prevent runaway boost from damaging the engine. It does this by cutting fuel delivery if it sees over 1 bar of boost for a short period of time. This is the sudden scary loss of power and it's also signified by the malfunction light on the dash.



You have decatted the car, fitted a boost controller that ups the boost beyond 1 bar, or have a problem with the wastegate system. Too much boost develops when giving it large.


How bad is this problem?

Short term it's a pain in the backside, but it can also be dangerous if you are caught mid-overtake or booting it round a bend due to the sudden abrupt loss of power. Long term it's accelerating wear on all drivetrain components.



Either lower the boost below 1bar mechanically (fix wastegate system, fit restrictor ring, refit cats), or fit a Fuel Cut Defender (FCD).


Other possible causes:


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