My '05 F250 (5.4) started misfiring and threw codes for p0300, p0305, p0307, p0308,and p2198. I used an inline spark checker to check cops, which all had spark. Replaced 5, 6, 7, and 8 plugs and cleared codes. Ran truck for a few minutes and codes came back. Switched #5 and #6 cops and cleared codes. 5,7,and 8 cylinders still misfiring (same codes). Truck only has 36,000 miles and spent alot of time just sitting. Plugs were original plugs. Replaced 5-8 with Autolite OEM replacements. I haven't checked cops for resistance yet. Weather was pretty cold when problem started. Threw in about 10oz. of Lucas to no avail. I had this problem last winter with the same cylinders throwing codes. Threw some Lucas in the tank and idled truck for approx. 1/2 hour and problem went away except for stumbling most every time truck came to a stop. I'm starting to wonder if it's a coil or a fuel issue. Any help would be appreciated.

 

You're doing good. P0300 is random missfire, the 305, 307 and 308 mean missfires on cyl 5, 7, 8. Google shows the 2198 is O2 sensor stuck rich. Have you looked over the injectors and fuel pressure? If the injectors are stuck open on 5,7,8 too much fuel could be putting out the fire and causing the miss. With three stuck injectors, I'd suspect fuel pressure to be on the low side. A good scan tool should also show injector duty cycles, if you have 3 stuck open they may show as 100% duty.

 

Thanks for the reply. The scan tool I'm using is an Autoxray 5000. I haven't upgraded it so it won't tell me every thing (such as duty cycle). I have to check it again but I believe it will give me fuel pressures. The injectors were my next target but I haven't got to them yet. Ford sent me a letter over a year ago informing me of a flaw with the injectors. Apparently the warranty on them was extended to 100k mi., claiming that they tend to stick. Thanks again for the help.

 

just wondering that since it sat if you put some injector cleaner in it again and drove at hwy speed would that help those injectors some.

 

Maybe. I used about 10 oz of Lucas oil and ran it approx. 1/2 hour, bringing it up to between 2000 & 3000 rpm a few times. No luck. Didn't really feel like taking out on the road with 3 cylinders missing. Injectors are my next area of focus.

 

Did you use Lucas thick oil in engine oil? GET THAT OUT you will risk destroy bearing on those engine. They aren't for those engine with tight bearing clearance

They use 5w20 oil that what it say on oil cap.


Did you try wiggle injector's plugs they could be loose and not make contact good cause this issues.

 

I've replaced many dozens of injectors on 2004+ 5.4 liters over the years. Your rich code combined with misfire is fairly common.

The easiest way to check for stuck injectors is to check fuel pressure. You won't notice any lack of pressure while the pump is running, the fuel pump supplies far more fuel than can be used by even all of the injectors being stuck open. If one or more injectors is stuck open, you will notice a rapid bleed off of pressure once the pump stops running.

Next, you will have to pinpoint the injector or injectors that are stuck open. There are several ways to do this: You can use an injector test rig, which I assume you don't have. You can also remove the fuel rail bolts on one bank, pull the injectors out of the manifold, and use zip ties to secure them to the fuel rail so that the fuel pressure doesn't blow them out. Cycle the key to the "on" position and inspect each injector tip for leakage. Another way to do it is to remove all injectors and use a rubber-tipped blow gun to blow air into the feed hole of the injector (regulate the air pressure down to about 50psi.) Smear some soapy water on the tip of the injector and check for leakage.

The fact that you have multiple misfire codes on one bank does not necessarily mean you have more than one leaking injector. The PCM runs each bank of cylinders as a separate four-cylinder engine as far as fuel control. The O-2 sensor receives the exhaust gas from all four cylinders of one bank, and therefore sees only the average oxygen content of those cylinders, not any one cylinder. When an injector sticks open, it causes the O-2 sensor to detect an extremely rich running bank of cylinders, which the PCM then tries to counteract by reducing the "on" time of the injectors of that bank. The PCM continues to reduce the injector flow until the O-2 reading goes lean again. It is possible to reduce the fuel to the point that the cylinders other than the one with the stuck injector will run so lean as to develop a lean misfire, and the PCM will set codes for those cylinders.

As for setting a code for a stuck injector itself, the PCM only has the capability to check injector circuit resistance, which doesn't change with a stuck injector. It cannot detect a physically stuck open injector directly.


Jay

 

Yes, I used the thicker Lucas Oil from Advance Auto. Didn't know about the potential harm. I did wiggle the wires but to no avail. "Fire Me", thanks for that procedure on testing injectors. I won't get to the truck until this weekend but I was planning on using the same procedure I used in checking the cops and switching the injectors with those on the opposite bank, where no codes are being thrown. Think I'll try your way instead. Thanks again.

 

"Fireme" What a great post! Your suggestions and information are invaluable! Thank you for posting this even 5-years later it helps us lowly folks!

 

Did you get your misfires resolved?

 

He hasn't made a post in 4 years, but mentions having the same truck in a post 2 years after his misfire post, so I would assume he got it fixed.