Hey all,

What would cause my engine temp to moderately increase 50 F or so, whilst crusing at light throttle, doing 60 mile/h at 3000rpm on the highway?

its just started doing it over the last few weeks. When I back off to an idle temp drop back to normal 185 F, when I give it some boost temp periodically increase to 197 F which again is normal, then quickly goes down to 185 when off boost. Its just that crusing temp which creeps up to 200 F which makes no sense.

I would have thought that under crusing conditions (mentioned above) temps would decrease due to the increase airflow to the radiator and intercooler), not increase.

Makes me think that it could be a timing issue, fuel issue or both. Could too retarded timing under crusing conditions cause this? or could it be caused by the fuel map (Microtech) being too lean under crusing conditions? Car has just recently come off the dyno where it made 400hp atw @ 18psi.

its doing my head in, any ideas?