3.2JTS engine - Cylinder Head Clattering

[Ascari32]

As a consequence of trials to reduce/eliminate excess fuel causing exhaust noise, experiments  conducted on the NTC Sensor found reducing the "effective" resistance of the sensor could quieten the exhaust roar in my Supersprint Sports Cat.

However, if taken too far: the effective value reduced too much, when the engine is ticking over, a severe metallic clatter develops around the area of the JTS fuel injection system of the cylinder heads.

Restoring the NTC to normal and the clatter disappears. This clatter only happens when the engine is idling and  not at any other engine speed. I can only think this effect is related to the amount of fuel, or more specifically, when the amount of fuel being injected, when the dosing element used to maintain catalytic converter "light - off", has been reduced  too much.

I have heard of some owner's engines displaying these symptoms. This being the case, a sensible, and very cheap way of eliminating any doubt as to whether they have a failing NTC Sensor is to replace it.

A replacement NTC Sensor costs less than £20 and takes less than ten minutes to replace. If in every other respect the engine is performing well, this component could well be the culprit.