Recently picked up a 1999 F250 Super Duty 7.3 2wd stick shift 03/99 with 70k miles. Truck runs great but will not pass smog because P0308 #8 cylinder misfire. I have Replaced valve cover gaskets,and installed a new CPS purchased from Riffraff Diesel Performance Parts. Truck still runs great but the code comes back once the truck reaches normal operating temp. I have always gone by the rule of don't fix if its not broke, however it will not pass smog. Replace the #8 injector? not sure what else is causing this code. working with standard diagnostic tools, I do not have a scan tool or a gauge capable of checking HPOP pressure to the injectors. Any advice would be appreciated. This is my first post I apologize if it is not in the correct forum thread ect.

 

Welcome. Let's see what we can figure out on your code issue. Out of curiosity what are you scanning codes with? If you check the tech section up in the stickies you'll find some very useful information about an app called Forscan. It is the best diagnostics software available for these trucks. With it and a compatible OBD2 dongle you can monitor all engine PID's, perform all available self tests, and save files to load here to help with diagnostics. The price can't be beat either, the PC version is free and the Android version is maybe $6. With it we can run a cylinder contribution test and check perdel's for a better idea of what may be going on. For starters though a fuel pressure test never hurts and it's probably a long shot but a PCM reset occasionally gets lucky. There's an easy fuel pressure test method in the stickies and the reset only need to disconnect both negative battery cables then jump one of them to a positive cable for a few minutes. Be sure to insulate the battery negatives so no accidental contact can happen. We want to reset the PCM not fry it. Oh, just remembered. Have you inspected the 42 pin connector at the driver's valve cover yet? Where the harness crosses over the cover it tends to rub and has caused many folks a lot of grief.

 

Ordered a Forscan adapter. Thank you for the information. Lots of good info in the sticky's thank you for the advice. I will reply with test results when it arrives. Please let me know what test results you would like me to post and I will do so.

 

Before replacing the injector, try swapping it with another one and see if the problem follows it.

 

Thanks for the advice, I might be wrong but I believe that the number 8 injector is different than the other 7, so I am not sure if I can do that?

 

It is different but it won't hurt anything moving it to a different hole. The long lead #8 was a band aid Ford used to try fixing an injector cackle warranty issue. Technically any 7.3 injector will work no matter the A code. It's just a matter of programming as to how well it will work.

 

Is the #8 injector different on a 3/99 manufactured truck?

 

I don't know for certain but have read that the AD #8's started with the L99's. Of course you know Ford so nothing is concrete.

 

ADs yes, but the long lead? I think it's an AE?

 

So it is okay to swap this injector with another for test purpose? If so then I can swap it with #6 and see if my p0308 changes to a p0306?

 

Yes your right I got mixed up there. Hey playas ef up.

 

Yes sir, no problem. Some folks call it Injector Whac-A-Mole, so have fun with it.

 

Yes sir it is.

 

If you go up to the stickies again, the link just above the Tech Section is the PID charting tool. It has downloads for our PID charting software and the instructions for using it. It's pretty sweet, it takes the exe file of a Forscan log and converts it to a linear graph that makes interpreting the data a lot easier. It also has the standard engine PID's for diagnostics listed. You'll also want to do an injector self test(buzz test) on a cold engine, and a cylinder contribution test(CCT) on a hot engine. Honestly though once you get Forscan up and running you'll be running all the tests it has just playing with your new toy. Don't worry, there's no shame or judgement here.

 

Thank you for your help. Forscan tool should be here in a day or two. I will post test results soon after.