I was pulling my 5th wheel camper over Monteagle Pass on I-24 (4% grade) and was nearing the top when my engine began to miss. It wasn't a random miss, but sounded repetitive or regular. Then I noticed that the fan was roaring very loud and my engine coolant temperature was up to 218 degrees. If I let up on the accelerator, the engine ran smoothly. After it cooled down a little, I didn't notice any problem.

Do these trucks have a safety programed in the ECM that limits the load on a hot engine, or do I have a problem starting. My truck is studded, O-ringed and deleted.

 

The PCM will begin to defuel at 221 *F coolant and 253*F oil temp

 

Thanks for that info. It's comforting to know that I was just pushing it too hard and that there is nothing wrong with it because I've got another trip planned soon.

 

I checked my 'Edge' programmer/readout and it indicagtes 220* as maximum coolant temperature reached. My engine oil got to 230*. I think I'll lower the Edge's alarm setpoint so I'll get an alert before I get this hot.

 

Visctronic should start to ramp up at 215 Coolant temp and s/b full engagement at 230.
It'll try and keep temps below the 230 but can spike under heavy load/grades. ECT, EOT, Trans ATF temp, Intake Charge Temp, AC demand etc are all players in the fans logic and operation..Fueling rate is modified 221-253 to help control for overtemp. ECT and EOT should be no more than 10* spread above 195..

 

Curious as to where have you seen the 10 degree differential specified?

 

10 from cold soak to heated/mod engine load EOT/ECT PID value variation..

Normal, 15*+ differential between the two under high load/boost may point towards a cooler restriction. Variation of 20-30 with a potential P012F on high, if he has the capability of monitoring both, may help avoiding an over temp fail. Reading the post, thought it odd that the visctronic was singing/lock below defueling numbers. Not by much, but curious what the EOT would have been under the same conditions..