Hey guys,
I was out 4wheeling this past weekend and got stuck in a mudhole. I had to *cringe* shut it off because I had to leave her and walk out to get signal on my cell. Anyway, when I got back I tried to start her and she fired up, but was running rough, like I was missing on 1 cyl. After the truck was extracted I had to get her out of the offroad park. On the way out she would run good if I gave her gas, and when I let off the gas, but if I was just barely feathering the throttle she would backfire and pop and wheeze. I got her to the outside of the park and checked a few things:
*Spark to all plugs: check
*Removed the ignition wire and turned the engine over to see if the motor was not getting compression on all cylinders. When starting it sounded good, no problems noticable there.
*Removed Cap and looked for water/moisture. There was none.
*Checked air filter, was just barely moist (and on in the box was a mouse nest! LOL! tells you how much i drive her!

She would still start up and run, and I didn't have anything I could do but just drive home. On the way home on the parkway she was driving pretty good, but when I would let off the gas and get her to idle speed the engine would turn off. The engine would start again with little to no effort. By the time I got home the plugs sounded like they had almost completely fouled out and was sounding like it was only running on 1-2 cylinders. I went out and got new plugs (Motorcraft gapped at .044). After installing them she fired right up and idled, but not for long. I took a small ride around the neighborhood and it didn't clear up.

The engine seems to be inhaling lots more fuel than it should. Lots of black smoke coming from the exhaust pipes. Being FI, I would think the computer would control that stuff.

BTW, the truck didn't sit in the hole on the distributor side of the engine, it was high and dry. the passenger side of the truck was buried up to it's doors and the frame rails.

Could I have blown an intake/exhaust gasket and that is why it's getting too much fuel as the computer cannot control the mixture at that point of the intake?

 

Just a couple of thoughts based on personal experience back in '66 when I buried my (brand new) car in a mud hole to a depth of about 1/3 up on the doors.

Check for mud or water that went into the tailpipe and partially plugged the muffler. At high engine speed, there's enough force to get through the restriction, so the engine appears to run OK (although it may still have symptoms). At idle, there's too much back-pressure.

You say you buried the right side more than the left. That's also the side the tailpipe/muffler is on, I presume, so that got buried too. While you waited to be rescued, thick muddy water could flush up in there (seeks its own level).

Also, depending on how thick the mud was in the hole, check for caked mud adhering to the inside of the tire rims as well as in the hubcaps (if you have them). If it dries up hard on you, you'll be wondering why you have a terrible shimmy as you go down the road at hiway speeds. Mind almost bounced off the road, literally, at any speed above about 35mph. I thought I had cleaned up everything (including about 4" of muddy goo out of the inside of the cab), but forgot about the inside of the rims and hubcaps. I didn't use the car for several days after I "cleaned" it, and during that time the mud dried out. At 35mph, it was like having huge wheel balance weights filling half of each tire rim. Must have been 10 pounds in each rim!

One last thought. Check to see if possibly the force of the mud that finally bogged you down (which I'm assuming was pretty heavy) possibly pulled on the O2 sensor wiring and pulled it out of its in-line connector. The sensor is on the passenger side, I assume, also, so at the instant you stopped you could be pulling the cable through the mud and it disconnected.

Just a couple of things to check. Please post back as to what you find, if anything. I'm interested & curious.

 

Well, I think i figured it out.
This is what I did this weekend:
*Ripped the intake off - replaced gasket
*Pulled valve cover
*Pulled intake/exhaust manifold
*Pulled off the head - replaced head gasket

I found out I had a cracked exhaust manifold. It was cracked on 2 of the 3 ports.

I don't know if that would cause the problem or not. I cleaned the hell out of that head/intake/exhaust. My parts bin cleaner is black now.

I got a used exhaust manifold for $40. Not bad i guess. At least it's not cracked.

So, I've almost got it all back together now. All I have to do is buy another coolant temp. sensor and bold the exhaust and starter back up. What a headache to work on this engine when the truck sits up so high. Does anyone out there have some pics of thier 300 w/FI so I can be sure I have the vaccume lines hooked up right? Kinda guessing at it right now.