A turbo timer keeps the engine idling for a short time after you turn the key off. After a hard drive, the turbo's center section is extremely hot. Shutting down straight away stops the oil and coolant flowing through it, and that heat can cook the oil left in the bearing housing. A short idle first lets things cool down gradually. The Time setting in the Nexus turbo timer is how long that post-key-off run lasts.
How we choose a time
- Start conservatively. A short cool-down covers normal street driving; there's no benefit to idling for minutes after a gentle trip.
- Think about how the car is used. A car that sees track days or long pulls earns a longer cool-down than a daily driver.
- After setting it, do a hard drive, switch off and watch the engine run down in a log, so you know exactly how long it idles before shutting itself off.
For the engine to keep running with the key off, the ECU has to stay powered after key-off. That normally means an engine control relay wired and configured so the ECU controls its own power.
Never leave a car running unattended during a cool-down, and make sure everyone who drives it knows it will keep idling. If you're on an Elite, see the Elite turbo timer.
