4.0 engine sputters horribly for several minutes after starting

[emoore1948]

4.0 Engine in my 2000 Jeep TJ with only 57,000 miles sputters horribly after easy starting in 112 degree weather. Lasts for several minutes and eventually smooths out, after forced throttle. Only does it occasionally, with no effect on gas tank cap pressure relief. The rest of time Jeep runs like new. What could it be causing this condition?

 

[Zorba]

Completely normal - you're getting "heat soak" in the injector lines. There's an FSB that addresses this issue that is a partial solution. I just feather up the throttle a bit for a few seconds.

 

[CharlesHS]

4.0 Engine in my 2000 Jeep TJ with only 57,000 miles sputters horribly after easy starting in 112 degree weather. Lasts for several minutes and eventually smooths out, after forced throttle. Only does it occasionally, with no effect on gas tank cap pressure relief. The rest of time Jeep runs like new. What could it be causing this condition?

Generally this is caused by the fuel inside the injector body heating up when the engine is shut off which cause gas to drip out of the injectors into the combustion chamber. Cylinder #3 is the most prone to this problem.
Does you Jeep have the heat reflective insulating panel on the intake manifold that goes between the intake manifold runners ?
There is a TSB that addresses this problem where there are insulating sleeve installed on all the fuel injectors body.

https://www.amazon.com/dp/B072HGFZ6W/?tag=wranglerorg-20

 

[Jerry Bransford]

X2 to the above, it very well could be caused by heat soak vaporizing the fuel inside the fuel rail/injectors. Jeep came out with a TSB that fixes the problem by wrapping the #3 injector with this insulation. Yes it says ignition shield but it works equally well as thermal insulation. https://www.amazon.com/gp/product/B007O3QHDK/?tag=wranglerorg-20

Injector #3 is the one that suffers the most from heat, I'd start there.

OR it could be caused by a bad upstream O2 Sensor which only becomes active when the engine has started to warm up.

 

[emoore1948]

Will try the injector wrap first. Presently has a silver heat shield panel. This 2000 Jeep TJ was a totally stock Motorhome Tow Vehicle with 57,000 miles on it, in near mint condition a couple of months ago. I just recently finished many major trail upgrades to it, with many custom modifications. My pockets are now empty as the saying goes, and this sporadic heat related condition just crept up to bite me.

Present Jeep Profile: 2000 TJ 4.0 5spd Sport with Posi Track Detroit Carriers and 4:10 Gearing, 33" Mud Tires, Deep Dish Alloy 15" Rims, 2" Lift & longer stroke Shocks, HookRoad swing out Rear Bumper with custom modified JK Jack Mount & green Hi-Lift Jack, EAG Front Bumper with changed out 12k Lumen lower bumper Spot, Boar Off Road 13k Remote Rope Winch, Wider Fenders for 10.5 tires, Glass Lens Reflector with 18k High Output Led Headlights, 54k Lumen true output Spots on upper bumper & roof that light up the world, Twelve green Rock Lights and centralized Relay/Fuse Control Box for all Led lighting. Many other upgrades include all Led lights from front to back & dash to floor, Double DIN Bluetooth Touch Screen Radio with Under Carriage Front Camera & Rear Backup Camera, Larger Polk Front & Rear Speakers, and a High Output CB linear setup.