Okay so I've noticed this for awhile now but it's really never been an issue, I'll describe the problem as best as possible, heck maybe it's normal it just doesn't "feel" normal.

If the outside temp rises above 90-95 degrees my truck becomes EXTREMELY sluggish, to the point where I don't think it could pull a trailer from a dead stop. Once up and moving its not an issue but stop and go traffic to and from work it's pretty noticeable. The transmission shifts goods

Things I've done / checked.

My HVAC works perfectly,
I flushed the radiator, had no effect.
There's no leaks around the water pump
I've noticed my tuner will read up to 206* on a hot day, is this normal? Maybe my tuner isn't very accurate sense it's not a true tapped line. Not sure

This has been going on for about 2 years now, it's more annoying than anything else. Thanks guys!

Not that it matters but I run premium gas.

Could this be a failing thermostat? It doesn't stick or read low and it comes down from 206 so that's why I'm lost. Thanks guys.

 

Is that coolant temp or air temp at 206*

 

That's ECT sorry about that

 

thats really warm not to be towing. im generally right at 190* unburdened but I have dual efans.

 

Yeah that's what I was thinking. Not sure what it could be, might just replace the thermostat sense it's not to expensive and see if that helps.

 

im wondering what shape your water pump is in. ive heard of the vanes wearing down and not flowing like they are suppose to.

 

Mine falls on its face in the heat. Very noticeable difference from 95-100 degrees vs 80-85 degrees. Night and day difference. Literally lol. I don't have a tuner to tell me any temperatures but yes. Sluggish describes it very well. I have a 4.6 though so it's sluggish to begin with below 3k rpm.

 

I also thought the same thing. There's no leaks around the pump but it very well could be worn down

 

Its normal. Ect is high which could mean a failing fan clutch. Your new heavy wheels an tires don't help. Its slot harder for the engine to make power with hot air especially with naturally aspirated engines.

 

Okay that's what I was thinking, they're definitely much heavier than my old set. I'll look into the fan clutch, I need to go ahead and replace the serp belt anyways it's looking alittle rough.