I have a 6.8 v10. I am still having trouble with the ignition system. I have a constant miss fire so I checked the spark plugs ( needed replacing) so I changed them and the oil all the filters etc new pcv valve and all new coils. I found a lot of crispy wires and connectors so I changed all those too. Connectors for the coils and injectors. Still have that Miss and it is getting worse. Now I have an exhaust leak as well from the passenger exhaust manifold found 2 broken stud's and one just missing. I also found an oil leak still haven't figured out where it's leaking from still looking. So I started to think to myself hell I didn't have these kind of problems out of my old non computer and sensor trucks . Why not change this one to be like them . So ok need a carb intake etc. but then I remember it's dual overhead cam. No cam below the valley . So I need to figure out how I'm going to do this . Is there a msd ignition module that controls the injectors And spark? And what about the transmission? When I make these changes do I need to change anything for the transmission? In other words is the transmission mechanical or computer operated? I'm rather old school tec back in the day when I used to make changes like this in the driveway it was straight forward. Now hell jsmh . Any help would be appreciated. Thank you in advance.

 

Computer for the engine controls, computer for the body and its functions as well. Oil leak? Like in the back of the engine in some mystery place? Might be the head gasket like my 99 V10 has started at 170K and not all that uncommon apparently. Find a 460/5 speed donor truck and go to town be my $.02 worth. I had a cherry 97 OBS, HD 250 4x4. Only complaint was accessing the back seat otherwise I should have kept it.

 

The oil leak is still a Mistry. There's not much room to look around . The oil is at the front of the motor somewhere up high. I was thinking maybe the intake but that is all clean I looked around the head's and and no oil coming out from under them . The oil is covering the front and blowing under the truck painting everything.

 

Wash down front of engine, put some dye (Napa) in the oil, black light bulb in drop light, and then start looking. I’d remove the fan shroud and maybe even the fan (spin some nuts or shorter bolts in to hold pulley in place). One can get a very inexpensive “boroscope” from Amazon these days (30 or 40), they connect to a phone and are fantastic for looking at areas that can be seen directly.

 

What year is your truck? There are some significant differences between generations of the 6.8 V10, so knowing what generation we are talking about will be helpful.

For your misfire, have you run a compression test to verify that you have good compression on all cylinders? Have you verified with noid lights that the fuel injectors are being commanded to fire? Have you checked the fuel pressure at startup and while running? Is one or more of the spark plugs wet after running for a little while? For firing to occur, you need air (properly compressed), fuel, and spark. It sounds like you have been focusing exclusively on the spark piece of this so far.