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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[@sheerwillsurvival2064]

Hope to see a part 2 and the fix

[@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.

[@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

[@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

[@faustogonzalez8397]

Thanks for your video, it was missing some critical circuit information. First, was this type ignition have a digital signal from the CPU into the Coil Pack that activates a Transistor, this transistor actually carries/controls the Primary Ignition Control current. Or did this type of Ignition System have a 12 Volt power feed directly into the Coil Pack ? Depending on the Ignition Primary Circuit Design, the troubleshooting/diagnostics will be different. I suspect since you were able to monitor Primary Coil current that this system has a 12 V driver , that supplies adequate Amperage ~ up to 19 Amps on the primary. Therefore, your Resistance you found created a Voltage drop loss and the proper voltage level was not reaching the Coil Pack Primary Circuit winding ? Low voltage due to voltage drop would create low Primary voltage collapse and therefore Secondary voltage would be very low and not ignite the spark plug therefore equals MISFIRE. Thanks for your video.

[@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 ?

[@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?

[@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.

[@brandonadviento4973]

I have a 2017 that is misfiring #2 only on a load (hard acceleration from a stop or driving past 65ish mph). Ever see that one? They’ve changed plugs and coil packs already, and compression test was good? Any ideas would be helpful because no one at the dealership seems to know what’s going on

[@joelde3746]

Nice video hope to see more video upload on frequent basis

[@jorgevillanueva2202]

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

[@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

[@bartscave]

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

[@DroidPADhome]

What year grand cherokee was it? The wranglers do this too but connector is on top of upper plenum ,

[@beastlychase]

Did you ever end up fixing this

[@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.

[@carlosdominguez8924]

Just started with this problem as well on 2019 JGC. Replaced Spark Plugs, Ignition Coils, Fuel injectors, spark plug tube seals, plenum seals and gaskets. P0304 code continues to pop up. Please update if anyone fixes this problem and I will do the same.

[@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

[@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...

[@FredFlintstone21]

What year jeep do you have? I'm having what feels like a misfire in my 2023 grand cherokee 3.6 liter with 5,700 miles on the clock

[@Ultimatesuperhero1]

I had that also ..code said fuel injector #1..didn't solve the problem

[@FredFlintstone21]

@Ultimatesuperhero1 i dumped a bottle of hydrotex injector cleaner in the fuel tank and problem went away.

[@MKF-x8o]

I heard it was the vvl solenoid. $15 fix

[@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

[@alexanderorozco661]

Thank you. Great information 🥋

[@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?

[@faustogonzalez8397]

NO

[@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?

[@Ultimatesuperhero1]

2015 grand cherokee..same problem..keep saying cylinder 2 misfire.smh i changed coils ..plugs ..and recently injectors ..and still didn't solve the problem..I'm going to have someone check out the wires..as this video mentioned..I'll leave update after it done 🙄

[@edwardthayer9386]

Hey any luck? I have a 2019 Dodge Durango 3.6 that keeps saying cylinder 1 misfire but only at higher rpm and around 50mph. Everything has been changed but still happening. I just don't know what to do next.

[@carlosdominguez8924]

Just started with this problem as well on 2019 JGC. Replaced Spark Plugs, Ignition Coils, Fuel injectors, spark plug tube seals, plenum seals and gaskets. P0304 code continues to pop up. Please update if anyone fixes this problem a d I will do the same.

[@tonydeonarain6309]

2014 Grandcherokee Summit, cylinder 3 / multiple misfire, replaced SPARK PLUGS, COILS and FUEL INJECTORS on all 6 cylinder, engine ride/idle quiet, ENGINE LIGHT BACK ON, any idea on my issue?

[@bryanreyna1509]

@@tonydeonarain6309did you find the fix ?

[@tonydeonarain6309]

@@bryanreyna1509 no fix as of yet, going for diagnose soon to a "expert", will keep you posted.

[@kirkholm5068]

Nice great job 🎉❤

[@edwardthayer9386]

Hey Jarhead or anyone that might have an ideal what my issue is id greatly appreciate any help or idea. I have a 2019 Dodge Durango 3.6 with 65k. I'm getting a cylinder one misfire only at higher rpm and around 50mph. Other then that the vehicle runs great. Before it got to me the coil pack, spark plug and injector were replaced with oem parts. It also has a new main battery. What i have done is checked compression, did a leak down, both were great. I swapped all vvts from bank 2 to bank 1 and still the cylinder 1misfire at higher rpm and around 50mph. Ive now took off the valve cover and everything is very clean and no wear.. id love to figure this out but i don't know what to do next. If you just drive the truck normal it runs fine with no problems, as soon as you pull out in traffic or pass someone it starts misfiring but runs fine once you let of the throttle. Thank you for anyone's time and input on this.

[@MKF-x8o]

Mine was a VVL solenoid replacement

[@zamiryi]

2:21 Backstory

[@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*

[@bruce6364]

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

[@screamingflat6]

Buy harbor freight, don’t wear matco hat

[@JarheadDiagnostics]

But I wasn’t wearing a Matco hat.