5.4 Liter engine lost power hot weather

dhally · 06-30-2021, 10:24 AM

So Silvan is at the Ford dealer in Prineville waiting for diagnosis. But I think this forum can diagnose it better!

Van has 50000 miles. I was towing about 1000 pounds and it was HOT, maybe 110F. As I was going up a long fairly steep grade, it lost power quickly but not like an off switch. After sitting with engine off for 5 minutes it restarted and had full power for about 1/4 mile. Then I gave up and called a tow truck.

My first though is fuel pump but everybody says it would not restart. Vapor lock? But that's impossible!

The shop is fully booked but they did say they would look at it next week.

Did I mention it was hot?

REDOVAL · 06-30-2021, 10:55 AM

Quote:

Originally Posted by dhally

So Silvan is at the Ford dealer in Prineville waiting for diagnosis. But I think this forum can diagnose it better!

Van has 50000 miles. I was towing about 1000 pounds and it was HOT, maybe 110F. As I was going up a long fairly steep grade, it lost power quickly but not like an off switch. After sitting with engine off for 5 minutes it restarted and had full power for about 1/4 mile. Then I gave up and called a tow truck.

My first though is fuel pump but everybody says it would not restart. Vapor lock? But that's impossible!

The shop is fully booked but they did say they would look at it next week.

Did I mention it was hot?

Replace your fuel filter as a $12 experiment. I just went through this with mine in hot conditions as well and 300 miles on a new filter. The van came to a halt with no power but did keep idling very poorly before dying reliably. We pulled the filter and verified the pump worked before blowing it out and reinstalling it. After that it worked fine to get us home. I do carry a spare filter and the tooling needed to change it, but this one was a surprise since the filter was new and the engine/nearly all accessories are also brand new.

Scott

carringb · 06-30-2021, 12:51 PM

Did you happen to see your transmissions temps? The PCM will cut power when trans temp gets too high. Around 240F at least on my 4r100

dhally · 06-30-2021, 02:31 PM

Quote:

Originally Posted by carringb

Did you happen to see your transmissions temps? The PCM will cut power when trans temp gets too high. Around 240F at least on my 4r100

I don't think my HUD has that parameter. It didn't feel like the ECU cutting power. I didn't get a check engine light but maybe the dealer can see what happened.

carringb · 06-30-2021, 05:19 PM

It won’t trigger a light when it goes into protect mode. Only when it still gets too hot (270 I think) even after reducing power. You definitely should have some way to monitor that temp.

dhally · 06-30-2021, 06:28 PM

Quote:

Originally Posted by carringb

It won’t trigger a light when it goes into protect mode. Only when it still gets too hot (270 I think) even after reducing power. You definitely should have some way to monitor that temp.

Are you saying the oem display should have it? Or that I should add it?

carringb · 06-30-2021, 08:27 PM

Quote:

Originally Posted by dhally

Are you saying the oem display should have it? Or that I should add it?

You need an OBD2 scanner capable of displaying it. I’m not sure if the Torque app does it. ScanGauge does but most years require inputting an “X-code”. You have and HUD? Heads Up Display? This might be able to display us as well.

DIRTRIDER · 06-30-2021, 09:27 PM

Hot air is an enemy for all gasoline engines. Cold air is much more preferable for burning=) But there is a complex. Hot air,hot gasoline, hot ignition coils and even a PCM. So i am agree that you should better buy a cheapest obd2 scanner with datastream option and you will get right info about engine condition.

dhally · 06-30-2021, 10:08 PM

Quote:

Originally Posted by carringb

You need an OBD2 scanner capable of displaying it. I’m not sure if the Torque app does it. ScanGauge does but most years require inputting an “X-code”. You have and HUD? Heads Up Display? This might be able to display us as well.

Lol. I just have the OEM multi function display. A bit of internet humor...

My Subaru has an oil temperture display. Which I did watch on my way home hauling the trailer and all the stuff out of the van.

DIRTRIDER · 06-30-2021, 10:31 PM

Quote:

Originally Posted by dhally

Lol. I just have the OEM multi function display. A bit of internet humor...

My Subaru has an oil temperture display. Which I did watch on my way home hauling the trailer and all the stuff out of the van.

What kind of temperature gauge do you mean? I am talking about air intake temperature, about MAF sensor readings and also about ignition. Air/fuel mixture is very important thing. Hope you are understand what I am talking about