Power loss while driving when hot outside

[rammons577]

2003 4.0 L Automatic 118,000 miles

On hot days in the summer, I will be driving along great at 35-40 mph and all of a sudden the Jeep seems to have lost power. I push hard on the gas as really nothing changes. After the Jeep sits for a while, everything is back to normal until everything heats back up after 20 min or so of driving. Only happens in the summer though never in the winter. Any thoughts? Already took it to the transmission shop to make sure that was not the case. Transmission looked perfect they said and no evidence of it overheating. Thanks guys! Really enjoy this forum!

 

[2001slvrstntj]

No help here, but nice looking tj from what I can see.

 

[Tycarver]

Have the same issue in mine.

 

[Jerry Bransford]

All I can think of is you may have an upstream O2 sensor starting to go out which will not usually turn the CEL on or set a diagnostic trouble code.

 

[Apparition]

Isn’t there an issue with heat soak on injectors? I haven’t had it so someone else would have to explain what happens.

 

[Wheelie]

It is basically vapor locking, in the fuel rail, very common on the 4.0.... they make a heat insulator kit that will fix it ... it’s about $50..... and the heat soak issue is also common , but that usually happens when you shut one off , and the #3 injector gets hot and causes a misfire when you restart it a little later

 

[reddvltj]

Isn’t there an issue with heat soak on injectors? I haven’t had it so someone else would have to explain what happens.

The heat soak, to my knowledge, (because I have that problem), only effects startup after a warmed up engine sits after shutting the engine off, it only takes a few minutes, then you have a longer than normal crank time to start.

 

[Brianj5600]

Are you in OD at 35-40? What RPM?