Turbo gauge reading flutters erratically and engine temperature spikes

[VBreithaupt]

Here's a new one that I don't see a thread on. I have a 2020 Limited Max
I was pulling my empty car haul trailer on highway going 70 and I look down at my turbo gauge and it's bouncing erratically and at the same time my engine temp comes up reading 225 and increasing. I let off the accelerator and the turbo goes down normal and the temp. starts decreasing. I hit the next exit and by the time I get to the stop sign the temp goes back down and stops displaying and when I accelerate the turbo gauge works normal. After stopping and checking oil and coolant levels ( both normal) I continue and tried to duplicate scenario. If I stayed on the accelerator to keep the turbo boosting at higher level it would start to flutter again and I was able to get the temp to display and start to spike again. I decided I didn't want to strand myself so I tried to take it easy the rest of the trip. On my return trip the turbo gauge again started bouncing erratically from time to time even at low levels of boost but I wasn't able to get the turbo boost for sustained level to get temp gauge to spike( I wasn't pulling the trailer anymore- less weight). Engine light did not come on. What is the correlation with these? Do I have a turbo going bad which would cause the engine temp to spike?

 

[VBreithaupt]

Update on my temp. spikes. After many people mentioned replacing the thermostat, I replaced mine this week. I wasn't sure if I had the new design thermostat in my 2020 but after removing, it confirmed I had the old design. I replaced with newer one and took my smaller trailer out and it seems to have fixed my temp. spikes as well. I still need to test with my travel trailer but I think that was the fix. The dealer had no clue on how to fix this when I originally brought this to their attention. I ended up doing this swap myself. I don't even think the extended warranty covers this. ( It doesn't cover the poorly designed heater hoses). It is 3 bolts that hold housing on. I didn't bother removing coolant or tubing ( Yes lazy). Made it a little harder getting the one bolt but can be done and it wasn't that hard. My replacement thermostat didn't come with a new rubber seal so make sure you take that off the old one and put on new one. Topped off and ran, and rechecked levels.

 

[East-TN]

Bummer your dealer didn't have a clue as to what was causing the temp spikes, it's been documented/proven on this Forum the older model Thermostats are failing and not working properly. I replaced my t-stat with a slightly colder part and my temps are 20-30 degrees cooler on my road trips than previously. And my transmission is cooler/happier too.

 

[apex96]

Turbo surging isn’t related to temp increase. Just a coincidence that when you’re climbing a grade and the turbo surge occurs you’re also experiencing temp increases. When you see the erratic turbo surges simply roll of the throttle a little and then get back on it, they should stop quickly.

It occurs whether you run a tune or not. It’s likely due to flow disturbances from the throttle body. The engine is lugging in a high gear and the PCM is calling for boost yet the throttle body is not opened enough to accept the charged air. The air then bounces off the throttle plate and the reverb also impacts the turbo vanes and causes fluctuations you see on the gauge and can sometimes feel too.

These are my experiences and thoughts on it. Now if I’m wrong I hope someone else can give a better explanation as to why we see surging with these 3.5 engines. Never had this with the F150 2.7 ecoboost.