97 5.9L V8 - Cylinder 6 misfire
Started happening about 1 month ago. Not so bad when in drive, but noticeable hard idle when stopped in drive. Especially rough when backing up slowly. When parked or with higher RPMs everything is fine. Taken to mechanic when purchased and new plugs and wires. Still problem. Taken to mechanic 2nd time and new distributor cap and rotor. Still happening 10 minutes after leaving shop.

The mechanic stated when I picked it up that it is only misfiring 8 times over 3 minutes in the shop. Then it will go away, then start misfiring a couple of times, then goes away. The other cylinders are fine, it is just Cyl6. I would like to have some tests I can run to see if it is just a fuel injector gone bad and what steps I need to take to replace the fuel injector. Also, is it advisable to drive without the fuel injector plugged in if it is not working or leave it plugged in? If any of the masters out there in cyberspace need more info or pictures, let me know!

 

OK, I've been there so here are a few suggestions:
1) Read this TSB and be sure your plug wires are routed correctly.
2) If you have the Field Service Manual, read up on relieving the fuel pressure, pull the fuel rail, and remove #6 injector. You can download the FSM from here. It is a zipped file and a valuable resource. Also note that whenever the fuel rail and an injector are removed that it is a good idea to replace the o-rings. They are cheap from your local FLAPS, and it's good insurance. Lubricate the new o-rings with a light coat of engine oil.

When you pull the injector, don't be surprised if the inlet side looks like this:


And there is a possibility that your fuel rail may look like this:


This is what mine looked like when I tore into my engine this past spring. I reused the injectors. How? I learned from a mechanic that injectors either work or they don't. He further explained that the race car engines he maintains are cleaned using solvent while run in an ultrasonic cleaner just like how jewelery is cleaned. I couldn't find an ultrasonic cleaner with a basket large enough to handle my injectors, but a friend of mine who owns a jewelery store offered to do it for me. They came back looking like this:


I also cleaned out the fuel rail very thoroughly. It seems that on the Dodge trucks, injectors #6 and #8 tend to collect debris as they are in the far back portion of the fuel flow. How many miles are on your truck? The pressure regulator acts like a last-in-line fuel filter. Here's what mine looked like:


Regulators run about $20 or so and it's money well spent. Say you find a sonic cleaner for $100 and use it to go ahead and clean all 8 of your injectors. Since the injectors run about $70/ea, 8 X $70 = $560. If you buy an injectors, but the others are dirty, you'll end up spending more money in the long run than if you had bought a sonic cleaner in the first place.

Just my suggestion and some food for thought. Plan on spending an afternoon on this project.

 

Thanks for the details VWD. From what I have described you agree that is might be a bad injector? To answer your question, I have 101000 miles. I understand what you are saying about cleaning them with a sonic cleaner, but how did you clean out the fuel rail? Is there anything more than releasing the pressure in the fuel line, unbolting the fuel rail from the block, and unplugging the main gas line to the fuel rail? As I am not exactly thrilled with the design of the engine compartment where a good 7 inches of the block (including the distributor cap) is located tightly under the body, are there any parts of taking out the fuel rail that involving getting behind the engine? Any ideas on where I can find a sonic cleaner? Thanks again, I really like the details you put in your posts!

 

The fuel rail is very easy to remove. As I stated, download the Field Service Manual and read up on the fuel section. There is no special tool needed to remove the fuel line from the fuel rail. The clip is easy to pinch and remove. I suggest relieving the fuel pressure back at the tank. Again, it's easy to do. Remove the line from the regulator and have it wrapped in a rag. I bought a pair of household rubber gloves for when I work on the fuel system and/or in my solvent tank.

Anyway, remove the air cleaner and associate hardware. The fuel rail simply unbolts, and then you gently lift everyone out. Work your way around, as the injectors are clipped into place. The injector clips are easy to remove. Once you get everything out, start your inspection.

As for a sonic cleaner, try Sam's, Costco, or even a beauty supply store. I know they're out there. For cleaning the fuel rail, I took mine to the engine machine shop and had them run it through the cleaning solution. Then, rinsed it with solvent. At 101K miles, I would highly recommend replacing the pressure regulator. It's very easy to do. If you need one of those clips that hold the hose to the regulator, hit me up and I'll send you one. They are easy to install.

Hope this helps. Let me know if you need any more information or have any other questions.

 

VWD, like I said...amazing detail...very professional and appreciated! Kind of funny when you think about it, I can completely tear apart a modern computer, not label anything, and put it back together without loose ends....and I am worried about unbolting 4 bolts and pulling a rack with 8 gas squirting thingamajiggers out of my engine!

I found a really good price on a sonic cleaner on EBay 2.46 pints for $50 plus shipping. Now, what kind of solute do I need to put in this thing as I am guessing the jewelry cleaning solution won't be what I want to use. I have the perfect place to take the fuel rail to, just want to get the right cleaning solution for the injectors. Is there any special tools you would suggest for put on and taking off the O-Rings? I have access to Chilton's Online and it says to get a special tool to get the O-Rings off...is this necessary?

A little history on my Dodge. I bought it about 18 months ago and have been very happy with it. I bought all new tires for it, nice 8 plys. I knew when I bought it the front brakes needed to be replaced completely, which was the first time I ever worked on a vehicle before. Used Chilton's Online and a hand from my dad and did both rotors, both calipers and pads and worked great. Put in a new stereo...of course. I did pay a mechanic to do new plugs and plug wires as I was worried to screw something up. Now once I get this step completed and things are fixed I would like to know everything I can do regular maintenance wise on a larger truck like this to make sure the thing stays in TIP TOP shape! Since you and others on here seem very helpful, I would like to ask as I am young (27) and don't even pretend to know how to REALLY take care of a heavier vehicle like this....again THANKS!!!

 

Hey, I was gone all weekend and am now recovering from the trip. My friend used plain old solvent. That's not going to hurt the injectors one bit. Since you're going to replace the O-rings, just yank them off. I used a small pick that has a curve on the end. Once you get done with cleaning an injector, let it dry for a while. I used plain motor oil to lubricate the new O-rings and gently rolled them into place. If it is going to be some time before you re-install the injectors, I recommend spraying them with a light coating of PBlaster and then sealing them in a baggie. I have several small zip-lock style baggies and wrapped each injector individually. When I reinstalled each injector, I again applied a light coating of oil to the upper and lower O-rings. You don't want them chaffed in the least bit.

On the first tank of gas I ran through my vehicle, I used Lucas fuel injector cleaner. It comes in a small bottle that can treat up to 30-gallons (IIRC). Dump the whole bottle into the tank. After that, I would recommend a bottle of either Lucas injector cleaner or Marvel Mystery over 5 tanks. Fuel injector maintenance is often overlooked, and maintaining injectors is very important.

Oh, and don't sweat your age or the size of the vehicle. I am a dumb computer programmer and have always wrenched on cars. I am no expert; however, I knew a self proclaimed expert mechanic who was terrified of front wheel drive cars and would never work on one. I did my own axle change on a Mazda several years ago, and it was a piece of cake. The more you dig in by reading the book, the better off you will be. Also remember that any tool you purchase is an excellent investment. Tools *always* pay for themselves.

Feel free to PM me or e-mail me if you have any questions. I will keep tabs on this thread. If I can't help, someone else will always chime in.