TSB: 18-031-03 (4.0L Rough Engine Idle After Restart Following A Hot Soak)

Jerry Bransford

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I installed a short piece of insulation around the 4.0L engine's #3 injection per a TSB (technical service bulletin) which is for 2000-2004 engines. It took about ten minutes from start to finish.

http://www.wjjeeps.com/tsb/tsb_wj_1803103.pdf

I had recently noticed a minor misfire after restarting the hot engine which had sat a short while causing heat soak. It felt like a single cylinder misfire and pretty sure this TSB will resolve it. The TSB describes a condition in which heat from the exhaust manifold (header) causes fuel to partially vaporize in the #3 fuel injector that can cause misfires after heat soak This is fixed by insulating the injector from the heat.

I used the specified Mopar shield ordered from https://www.amazon.com/gp/product/B007O3QHDK/?tag=wranglerorg-20

Several reported that not all types of insulation tried were successful with this TSB so I went with the Mopar insulation p/n specified in the TSB. There's nothing to the TSB other than cut the piece of insulation contained with that p/n in half and wrap one half around the bottom of the injector and the other half around the top of the injector, then secure it with a ziptie. The insulation was came pre-split so it just slides over the injector.
 
Just order this and the shield. Thanks!

I was still experiencing heat soak after wrapping injector three. If it doesn’t fix your heat soak issue, you may also need to also wrap injector number four. So far I have had no more heat soak issues after insulating both (so I now have insulators on injectors three and four), even with some brutally high Florida days.
 
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I was still experiencing heat soak after wrapping injector three. If it doesn’t fix your heat soak issue, you may also need to also wrap injector number four. So far I have had no more heat soak issues after insulating both (so I now have insulators on injectors three and four), even with some brutally high Florida days.

Thank you for the heads up! I may order the rest of them.
 
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