Code p304

mtbdemon · **Joined:** Fri Aug 24, 2012 5:15 pm **Posts:** 179

So, driving home tonight and my little liberty starting running really rough. I got it home (noticed a bit more black smoke) run the scanner and got a code p304
Now I have the sheets that tell me what that is, but I have no idea what to do about it. I do have a GDE tune, but that's about it. Oh, I do have the updated fuel head.
Anyone have an idea before I take it into the shop? Thanks

Ken
Beaverton Oregon

Hexus · **Posted:** Fri May 10, 2013 7:28 am

I don't honestly know why you would take it to the shop unless you just don't have the time to do it.

First you should replace the fuel filter, I would probably drain out the fuel lines afterwards.

P0304 is Misfire on Cylinder 4 detected.

WHATEVER YOU DO, DON'T MESS WITH THE FUEL LINES WHILE THE ENGINE IS RUNNING, IT OPERATES AT VERY HIGH PSI and COULD INJURE YOU HORRIBLY.

Tools Needed:

17MM Crow's Foot socket or Brake Line Wrench
Socket set 3/8" Drive
4" Extension
2" Extension
Carb/Choke Cleaner
Service Manual
Torque Wrench

I would go ahead and order 2 sets of Copper Crush Washers and O-Rings from ID Parts, will cost you about $10 shipped.

I would take #4 fuel injector out and clean it. Be careful around the nozzle area and don't use a brush there, spray it with Carb/Choke cleaner but don't brush stuff off. I would clean the bore of the injector recess with a 20 gauge shotgun brush or similar, and make sure there's no junk laying in the bottom when you're done, Shop Vac works well here.

Replace the copper crush washer on the bottom and the O-Ring about 2 inches up on the injector.

Bleed the fuel out and change the fuel filter while you are in there.

If that doesn't fix the problem, then you order a reman fuel injector and use the 2nd copper crush washer and O-Ring to fix your problem.

I doubt it's your ECU because you have a GDE Tune, but if you bought the scan tool Keith might be able to check the tune to ensure something isn't off with the tune or the ECU.

Good Luck, no matter what you decide to do!

mtbdemon · **Joined:** Fri Aug 24, 2012 5:15 pm **Posts:** 179

Thanks for the info-A couple questions

I can't seem to find a service manual anywhere and there seems to be a few different ones_which are the best to buy? Also, how would I know what size of crush washer and O-ring to buy before I start into this? I assume the service manual would tell me this if I had one.
Thanks again for the good info-

papaindigo · **Posted:** Fri May 10, 2013 10:23 am

You need to go to Sir Sam's NOOB site, which you should do anyway, and scroll down a ways for the link the the FSMs and Parts Manuals which can be downloaded for free. As far as I know there and no after market manuals; this forum and the Aussie one serve that function.

When you download the FSMs be sure to get BOTH the 05 and 06 regardless of the year of your CRD. The 05 FSM lacks the diesel cooling system sections and does not contain the diagnostic information (published separate in 05) but does have illustration keys while the 06 FSM is the exact reverse. Get the parts manual that applies to your year. The crush washer and "O" ring can be purchased from a local dealer likely for under $10

Hexus · **Posted:** Fri May 10, 2013 11:41 am

mtbdemon wrote:

Thanks for the info-A couple questions

I can't seem to find a service manual anywhere and there seems to be a few different ones_which are the best to buy? Also, how would I know what size of crush washer and O-ring to buy before I start into this? I assume the service manual would tell me this if I had one.
Thanks again for the good info-

+1 to what Papaindigo said, don't buy them, download the PDF for free and then you can look up codes like I just did and print out pages with step by step instructions like I have for numerous things.

If you go to IDParts.com and select your engine and model year then there will be a section for the crush washers and the o-rings, or you can call and talk to Corey (Who is a member of this forum) and he will make sure you get the right ones.

Just have them standard mailed.

mtbdemon · **Joined:** Fri Aug 24, 2012 5:15 pm **Posts:** 179

Sweet!! This CRD is relatively new to me, so I'm still in the learning process-One thing I have found out is that my local dealers are not much help, nor is there a diesel mechanic close that knows these engines-SO, its basically up to me to straighten this out...Thanks for all the help!

Ken

mtbdemon · **Joined:** Fri Aug 24, 2012 5:15 pm **Posts:** 179

Okay, after away for two weeks I'm finally able to tackle this problem. I downloaded the manual and that has been a help, but darn, the #4 is a hard one to get to. Also, I think my injectors are larger the 22 mm. Are there any tricks to this? With all the wiring in the way, I just don't see how I'm going to get a wrench on it. Thanks

Ken

Hexus · **Posted:** Mon May 27, 2013 9:06 pm

There is only 1 bolt actually holding the injector in, the rest of it just fits down in the intake recess.

You should be able to remove that bolt pretty easily with an extension. If you need to move the wiring harness out of the way just remove the 2(IIRC) retainers on the top being careful not to throw them across the garage/yard/driveway and gently (GENTLY, BE CAREFUL) move it enough to do your work.

If you need to disconnect any electrical connections, my advice is to label them with Butterfly bandages, wrap the skinny part around the wires and label the matching connector/connection A/A, B/B, 1/1, 2/2, etc.

I say this because there are a couple connections back there that are exactly the same, and while it won't immediately hurt your engine to switch them it will be a pain to figure out what is causing the CEL later, and why your engine is running like crap, rofl.

Use the 17MM crow's foot socket, and you can use an extension here as well. I've taken the whole fuel rail apart a couple times (don't ask) and it isn't too difficult, as with any work you aren't immediately comfortable with, set aside a whole day to do the work, and if you get frustrated, just walk away for a while and come back and look at it again.

Good Luck.

mtbdemon · **Joined:** Fri Aug 24, 2012 5:15 pm **Posts:** 179

Hexus wrote:

There is only 1 bolt actually holding the injector in, the rest of it just fits down in the intake recess.

You should be able to remove that bolt pretty easily with an extension. If you need to move the wiring harness out of the way just remove the 2(IIRC) retainers on the top being careful not to throw them across the garage/yard/driveway and gently (GENTLY, BE CAREFUL) move it enough to do your work.

If you need to disconnect any electrical connections, my advice is to label them with Butterfly bandages, wrap the skinny part around the wires and label the matching connector/connection A/A, B/B, 1/1, 2/2, etc.

I say this because there are a couple connections back there that are exactly the same, and while it won't immediately hurt your engine to switch them it will be a pain to figure out what is causing the CEL later, and why your engine is running like crap, rofl.

Use the 17MM crow's foot socket, and you can use an extension here as well. I've taken the whole fuel rail apart a couple times (don't ask) and it isn't too difficult, as with any work you aren't immediately comfortable with, set aside a whole day to do the work, and if you get frustrated, just walk away for a while and come back and look at it again.

Good Luck.

Thanks! So is the crows foot for the fuel line bolt? Why not just use an end wrench? Does the plastic piece at the very top of the injector simply pop off? It looks and feels fragile and I'm afraid that I might break it. Do I have to worry about any pressure in the line? Sorry for the silly questions, but I want to be sure I do this correctly. Thanks again

mtbdemon · **Joined:** Fri Aug 24, 2012 5:15 pm **Posts:** 179

So I got the little sucker out!!! :BANANA:

I have never pulled an injector before so I have no idea what it should look like. I cannot see any hole the fuel would squirt through. I downloaded a service manual, but can't find any close up pictures of the injector. Should I attempt to pull the bottom part of the injector off and clean it or is that a bad idea?
Also, when I pulled the injector it was covered with thick heavy oil or tar type of substance. Is that also normal?? Thanks

Ken

Hexus · **Posted:** Sat Jun 01, 2013 6:43 am

Don't pull anything apart on the fuel injector, if you google them they are $1500 new and $400+ rebuilt.

Spray the fuel end lightly with Carb/Choke cleaner and let the tar/goo just blow off. Get about 3 cans of carb/choke cleaner when you buy it. Use a soft brush to clean all but the tip (DO NOT CLEAN THE TIP WITH A BRUSH, YOU CAN WIPE WITH A SHOP RAG BUT NO BRUSH) you can brush the rest of the injector, leave the tip alone.

The tar is from your EGR, disable it via GDE tune. If you have it disabled, then this is old residue.

CATCRD · **Posted:** Mon Jun 03, 2013 12:04 am

The tip should have 5 or 6 nearly microscopic holes that spray the fuel down and outward in a radial pattern. Don't brush them.

thermorex · **Posted:** Mon Jun 03, 2013 8:54 am

Yup, x2 in what hexus and catcrd said. I used a lint-free shop rag to wipe out the injector tip very well, till no black will get on the rag. I think.there are 5 small holes, took me forever to see them, a magnifier can help.

mtbdemon · **Joined:** Fri Aug 24, 2012 5:15 pm **Posts:** 179

Okay, we'll I'm learning something everyday!! For the life of me, I could not see anything, but since they are under intense pressure I suppose it makes sense that they are microscopic. I really hope that cleaning it will take care of it as that one against the firewall is a real bear!!
Thanks for all the feedback!!

Ken

mtbdemon · **Joined:** Fri Aug 24, 2012 5:15 pm **Posts:** 179

So now an update...I have actually pulled and installed the #4 injector twice. I tried cleaning it the first time and since that didn't fix the problem, I had the injector tested and it tests fine.

So, after installing everything it still runs the same and after erasing all codes it pulled a code P304 again. So, what would be my next step? Is it take it to a shop time? Thanks

Ken

CATCRD · **Posted:** Wed Jun 11, 2014 12:35 am

How about swapping the injector with another cylinder?

mtbdemon · **Joined:** Fri Aug 24, 2012 5:15 pm **Posts:** 179

CATCRD wrote:

How about swapping the injector with another cylinder?

But if the #4 injector tests fine, what would I gain? Not trying to argue, just curious as I know very little and even less about these engines : ) Thanks for the help!

Ken

BlackLibertyCRD · **Posted:** Wed Jun 11, 2014 10:57 am

You need to take compression of that cylinder and maybe another one to compare.

mtnmed71 · **Joined:** Thu Feb 27, 2014 6:17 pm **Posts:** 20

mtbdemon wrote:

CATCRD wrote:

How about swapping the injector with another cylinder?

But if the #4 injector tests fine, what would I gain? Not trying to argue, just curious as I know very little and even less about these engines : ) Thanks for the help!

Ken

...process of elimination. If a different injector has the same misfire issue in the #4 cylinder then it is either not getting the signal to open or the cylinder lacks necessary compression. I hope it is not the latter.

SargeIndustries · **Posted:** Wed Jun 11, 2014 3:29 pm

Try physically unhooking each injectors plugin while running. A couple of times my CRD would set a cylinder misfire code that was actually one cylinder off. I would also squirt some bubble soap around the injectors while running to see which injector is leaking.

Code p304

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