On my friend's L28ET swapped 280z, we are having this weird issue.
It seems that the CHTS reads off, but thats not the weird part. If we turn on the electric fan, it will go crazy! Sometimes hitting 350deg indicated, all very rapidly.
Then it will settle down around 170deg, with spikes in the upper 200s. (170 sounds right, with the 160deg thermostat).
If you flick the fan off, again, it goes nuts, sometimes killing the engine if the idle is low, as it throws the enrichments off.
Any ideas?
Mario