JamesO
New member
I have actually logged the intake temps with a cone filter behind the bonnet catch and yes the temperature does indeed rise when moving slowly but once at speed it's back down to near ambient. I relocated the filter behind the headlamp mostly due to water being thrown up off the crank pulley causing problems soaking the filter during very heavy down pours. your issue could be the inlet temperature sensor becoming heat soaked in the hot engine bay causing the ecu to pull back the timing as it thinks the air is hotter than it is.