Jeep Grand Cherokee 3.6 Misfire- Case Study

This Jeep 3.6 misfire took my lunch money and left me crying. But in this video I go over how dynamic changes, can cause issues in your standard diagnostics process.
This is my first attempt at a case study style video. So lets see how this pans out.
Load Test Light:
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Lead Hook:
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Multi Meter Leads:
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Merch:
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[@genebartle7715]

I've been an electronic/electromechanical tech since 1985. Thermals can definitely test your patience, freeze spray and a heat gun can be your best friends. I commend you on your troubleshooting ability and good explanations.

[@sheerwillsurvival2064]

Hope to see a part 2 and the fix

[@jwoeltje6949]

I’ve just recently had a similar situation happen to be with a fuel pump. I load tested the wire And ohm checked all good. But after the car would run for about a half an hour the car would break up like I was losing fuel pressure. Well ultimately I created this issue myself. I installed an upgraded fuel pump and I had to go with larger gauge wires so I used the solder connectors to connect my relay to my new pump. When it would get hot the wire that is it would heat up enough to loosen the solder. Creating a loose connection. I found it with my thermal imager

[@bartscave]

Thanks for sharing the challenges of this diagnosis Brandon! Thanks PJ also.

[@valshin]

I usually put some load, like 100w bulb through the wire to confirm it is ok, wiggling the harness simultaneously. Also it worth to pull the wire with some force, if it is weak it will break.

[@JarheadDiagnostics]

We do as well with our load test light. This one just threw us for a loop due to only failing when hot.

[@flippintobyland7257]

@@JarheadDiagnostics in hindsight is there a good way to diag for this possibility, would leaving the test light on there for a few mins start to dim the light ? I know not normal just wonder if the test light would pick up on this ? Also when loading a circuit is there a rule of thumb as far as how much load the light bulb should put on the suspected circuit? I dont see anyone mention this , basically if a circuit usually carries a 15 amp load could you get into a situation where your test light indicates a good circuit BUT only because the load ( light ) you placed on it was not enough or will it always dim enough to see the issue ?

[@christiancassidy2848]

Any fix on this? Been dealing with this for two years now have tried so many things and it just won’t go away

[@shawnkirkpatrick9379]

Great video I recently got my butt kicked on a Honda CR-V with a similar issue on the fuel pump connector. Mine was hard to find because it was so intermittent. I assume that even if you would have load tested the circuit with a headlight bulb it would have shown good until the circuit was hot enough.

[@joelde3746]

Nice video hope to see more video upload on frequent basis

[@jorgevillanueva2202]

I'm having the same issue with the same veichle.

[@alexanderorozco661]

Thank you. Great information 🥋

[@VoltageDropDiagnostics]

Good video Brandon! What did you end up finding in the harness though? Was it that connector?

[@JarheadDiagnostics]

We never pulled the intake back off. Customer opted for an overlay.

[@jimenezautorepair4450]

Im having a same issue misfires in 1-3-5 only on idle and its not always their some time s 1 and sometimes 5. And some times 3 lol but its their

[@joshslavin9294]

Same here, any fixes?​@@jimenezautorepair4450

[@jayscholl7280]

I have a Misfire on Piston 1. Not the Plug or coil pack. I brought it to a Jeep dealer they couldn't figure out why ? This may help...

[@kirkholm5068]

Nice great job 🎉❤

[@beastlychase]

Did you ever end up fixing this

[@kristendunaway5373]

This was a vehicle I just purchased used from a dealership with warranty but refused to cover. Engine light came on day after purchase. Cylinder 6 misfire. All spark plugs replaced. Ignition coil replaced. Pcv valve replaced. Next step I was told is new motor for $9000. It doesn’t run bad, and I don’t notice any issues. Can I continue driving it or is it something I need to either replace or get rid of?

[@JarheadDiagnostics]

I wouldn’t recommend driving it on a misfire. Where are you located? I may be able to recommend a shop that can properly test the system.

[@puremayhemFTW]

Same exact thing is going on with mine. 2018 Jeep grand Cherokee. 3.6. Started out with a p0306, pulled the plug and the plug was broken on the tip by the electrode. I said well it’s got 71k miles so I’ll replace all the plugs sense they’re due at 80k. Misfire was gone. One week later started missing on cyl 6 again. I pulled the plug and could See some carbon tracking on the electrode. So I put another new plug in and a coil. All good. Exactly one week later started missing again on 6. Haven’t had time to get back into it yet. Trying to think of what could be taking out that plug in a weeks time.

[@tobymanning3658]

Same issue here… 8-9000$ to fix issue… Mine runs fine, other than the check engine light on..So I disagree with his response… been told by various certified mechanics that it’s fine to drive if no issues while driving

[@alanw5879]

Was this resistance on the coil control wire, or power feed? I think I missed which wire it was.

[@JarheadDiagnostics]

Control wire.

[@alanw5879]

@@JarheadDiagnostics ok thanks, Im having a somewhat similar situation. Pretty interesting on these new jeeps that they have intentional shutdown of the ignition coils. Jeep is the first manufacturer I think Ive seen do this. Not just the injector anymore.

[@MrSatastic]

I would guess the faulty aftermarket coil was the cause that started this

[@ventacasaciudadjardincali1321]

The other day I unscrewed a coil while still connected and working, the engine was on, I had a screw driver in my hand , I had no shoes, and I accidentally moved the screwdriver near to the coil spring and I received a current shock for about 1 or 2 seconds, do you think this could have affected de coil driver at the pcm?

[@KingKrondo]

2020 GC limited 3.6 with 195+k on it replaced egr valve & cooler codes gone for two months and now misfiring again? Only when driving at idle no cel? Any suggestions or ideas?

[@sv_endless6340]

So even if the engine is running the resistance has to stay between 10 and 14 ish according to spec. I have a 3.6 jeep and it has a no 1 miss fire only. My codes is P0201 P0202 P0203 P0204 P0205 P0206 open circuit. But every injector test right resistance, when cold, right wire resistance, when cold, they have control 12 V and constant 12 v from fuse ,when running only, the resitance do climb when running on all injectors. compression test is perfect. I am lost. If the ecu was fried it would not give me control or any signal or voltage. I did scope it and it seemed fine, not a pro at using my scope yet. I did link a bypass wire like you did no change. Any advise please

[@DirtyWorm12]

The shorted coil cooked the control wire?

[@DirtyWorm12]

Sounds like you took the right steps, minus the rabbit hole. how come it always seems like to bite us in the ass when we don't do a full diagnosis for ourselves. What did you end up finding?

[@DavidRomanKC]

Are a hostage? What's with the dark footage?

[@JarheadDiagnostics]

Hostage for your love.

[@nickayivor8432]

Happy New year 🎄 🎉 ✨️ JarHead Diagnostics My teacher JarHead Diagnostics SUBSTANTIAL JarHead Diagnostics Thanks for sharing what you know with us Thank you very much helpful information video SUBSTANTIAL JarHead Diagnostics From Nick Ayivor from London England UK 🇬🇧

[@charmionrippentrop2881]

🎶 *Promosm*

[@screamingflat6]

Buy harbor freight, don’t wear matco hat

[@JarheadDiagnostics]

But I wasn’t wearing a Matco hat.

[@bruce6364]

blah blah blah ..... too much talk, no action