04 Jeep Grand Cherokee missing issue

[allaboutthebirdsj]

thanks for the add- I have an 04 Jeep GC w/ 4.0. It suddenly began missing and my code reader said it was p352 ignition coil B primary/secondary circuit. Soooo since the Jeep has 165K on it and I do not know its history- I replaced all the plugs, the coil rail (all the coils are made into), all the injectors, the fuel filter and air filter. IT still is missing and throwing the same code. I did pull the plugs after firing it up for 2-3 minutes and #4 was blackened heavily so did a compression test- all cyl are about 160. I am at a loss as to where to look next-
One other thing to note- since I have had it (about 4 m)- to crank it up, you have to turn the key on, give it a moment then start it. If you dont give it that moment- it will just spin over and not start..

Help!!!

 

[meep]

welcome to bitog!! Sounds like at the minimum, plug 4 could be fouling. Clean that and there’s a chance the misfire will quit for a bit. 165k is not a big deal for the 4.0, but there could be a valve seal starting to weep oil into the cylinder, causing the fouling, if that’s what it is.

the slow start makes me wonder if the fuel pressure regulator is getting a bit tired. It’s a 1-bolt swap but a little pricey at around $75 for the part iirc.

edit. Also a possibility there’s a fuel injector dumping too much fuel into #4.

 

[Chris142]

What plugs did you put in it?

 

[allaboutthebirdsj]

All the plugs, injectors, fuel filter, coils, boots were replaced two days ago- it was run for 3 min and the # 4 plug fouled in that time. I think the plug fouled due to no fire on that cyl but I would think another plug would exhibit the same signs given how there are 3 coils for the 6 cyl..IDK...

 

[allaboutthebirdsj]

I should have also stated that the fuel filter has the regulator in it and that was replaced at the same time as all the other work... A couple of the wires to the injectors were cracked and bare so I redid the suspect wiring (that was on cyl # 3) this one has me scratching my head no doubt

 

[kschachn]

thanks for the add- I have an 04 Jeep GC w/ 4.0. It suddenly began missing and my code reader said it was p352 ignition coil B primary/secondary circuit. Soooo since the Jeep has 165K on it and I do not know its history- I replaced all the plugs, the coil rail (all the coils are made into), all the injectors, the fuel filter and air filter. IT still is missing and throwing the same code. I did pull the plugs after firing it up for 2-3 minutes and #4 was blackened heavily so did a compression test- all cyl are about 160. I am at a loss as to where to look next-
One other thing to note- since I have had it (about 4 m)- to crank it up, you have to turn the key on, give it a moment then start it. If you dont give it that moment- it will just spin over and not start..

Help!!!

That's quite the parts cannon you shot at it there. Just make sure you keep stuff out of the oil fill hole.

Can you post a video of the misfiring engine?

 

[mk378]

When it does run, is it running on only 4 cylinders? The code suggests the coil driver for one of the three ignition coils (two plugs per coil) has detected an open circuit. I think the PCM drives the coils directly here. Get a schematic of the car and test the wiring from the PCM to the coils.

 

[Fordiesel69]

Jeep = Wiring issue......

 

[t1snwrbrdr12]

Common for harness problems behind the head/against the firewall.

Common for the fuel pump to bleed back pressure when the jeep is off, causing a long crank. Cycling the key is helping prime the fuel system and start it (if loss of fuel prime IS that issue). The jeep should run fine with this issue and can be ignored. Your ignition problem is a separate problem.

Also keep in mind the 1st year of the WJ 4.0 had a different coil pack than all other WJ 4.0 for some reason. I witnessed one of our top guys literally almost go crazy diagnosing why a new junkyard engine wouldn’t run right (or run at all, I can’t remember the exact issue) after the engine was swapped with a good junkyard engine. Coil pack was reused off junkyard engine and was different than what was needed for the model year the engine went into.

 

[meep]

New plug fouled in 3-4 minutes?

 

[Quantico]

Not my area of being an expert on that car....but i would look at fuel injectors and mass air flow sensor. To start with.

 

[The_Eric]

New plug fouled in 3-4 minutes?

Yeah that's kind of funny. Sounds like it's firing - if it weren't, it should have been wet and white.

Wonder if an injector is stuck?

 

[allaboutthebirdsj]

Hi All- so as stated, I replaced all the injectors, cleaned the MAS, the code is the same as it was before I dove in- I purchased a new coil rail for the correct yr model- I did notice that earlier models had different part # but the '04 one is what I purchased. I tend to suspect that there is a broken wire somewhere in the harness (as stated above, I feel it is in the trunk part at the firewall) I am hoping to get to it this coming week,
I would suspect something else or a faulty new part except for the fact that the miss and the code is the exact same prior to any new parts being installed.
To clarify all the following was installed in the same day- new coil, boots, plugs, injectors, fuel filter, repaired fuel injector wiring, cleaned MAS. I would crank it between each component install excpet for coil and plugs- those went in together.

Thanks to everyone who has chimed in-

 

[The_Eric]

Thanks for the update - please let us know what you find.

 

[Kuato]

I had a 2004 with similar problems… Turns out the battery cable was corroded, INside the insulation, up to about 9 inches from the positive battery post… So check your battery cables for corrosion.

 

[clinebarger]

When it does run, is it running on only 4 cylinders? The code suggests the coil driver for one of the three ignition coils (two plugs per coil) has detected an open circuit. I think the PCM drives the coils directly here. Get a schematic of the car and test the wiring from the PCM to the coils.

This is the post you need to read!!!