[FONT=Times New Roman][SIZE=3]I have a 2007 F150 SC, 2wd, with a 4.6 engine. The truck has 73,000 miles and I’ve had it for 8 months with no problems. A couple of weeks ago I had a bad vibration but didn’t get any CEL. I wasn’t sure if it was the engine of something in the drive train. The next time I drove it, there was no problem. The miss quit and was good for a couple of weeks. All of a sudden the miss is back and much worse. The CEL comes on and the gas mileage dropped to about 8mpg. I took it to AutoZone and the scan showed multiple misfires on 3 and 4. He said it also showed an O2 sensor problem. According to him it was probably the coil. I bought one coil instead of the two he wanted to sell me. I figured it would be unusual for two coils to go bad at the same time, and if I changed one then the miss should be less. If that was the problem then I would change the other coil. There was no change. I bought a code scanner and it shows a 172 bank 1 rich condition, a 300 multiple misfires, and a 303,304 cylinder misfires. I also have a pending o2 sensor code but I don’t remember the number, it was a 21xx something I think. How do I check the coil? It also has a ton of white smoke coming out the exhaust at times and you can smell the raw gas from that. There is no overheating problem so I don’t have a head cracked. It's very hard to start and seems to run better at higher rpm's. I've tried dry gas but no change. Other than spending money I don’t have at a dealership, what else do I check? I didn’t see any vacuum hoses problems either.

 

Nobody has a clue?

 

White smoke is usually water / coolant burning. Look close at oil cap bottom, dipstick, and the radiator cap and pressure/expansion tank (overflow tank for radiator) if you see any white on oil cap or stick or cruddy looking water in cooling system it is head gasket. Since it shows misfires it also may be intake leak - which in right circumstances can cause water in intake. The easiest way to find vac/intake leak is to spray carb cleaner all around the edges of intake while running. Spray at intake edges, hoses and their conections, etc and if motor speeds up or stumbles you will find your intake leak. Especially if intake is leaking at edges of the cylinders you have the misfire in. If not a real ball breaker you can pull plugs and look close at white porcelin on tips to see if slight stain (green if your using regular green anti freeze) that shows coolant getting burnt. But intake leak will give you all the misfire and rough running codes and then o2 sensor gets real bad readings from what is being burned. Try spraying to look for intake leak but only if your other checks are sure head gasket not gone. Are you slowly seeing a loss of coolant, or overly high pressure in the coolant tank?

 

When I saw all the white smoke coming from the exhaust the first thing I thout of was a cracked head/gasket. I've drove it over 300 miles (sometimes it sucks to live in the middle of nowhere) and the temp never got above normal. No change in the coolent level either. I'm 99.9% sure it's not the head gasket. I'll try the spray around the intake/hoses and see it anything changes. When it's running there is a strong fuel smell.

 

White smoke is normally a real strong indication of water/coolant as I said. My wife had a Toyota truck that had a very slightly warped head that would loose very tiny amounts of coolant over a week and smoke like that at times. After a month a check of the plugs showed a green tipped one so I could tell which cylinder it was. The best way to tell for sure is to get a cylinder compression tester (not that expensive) and do a compression test on all the cylinders. That will tell you for sure if one or two are very low compared to the rest and tell you for sure if it is a cylinder leak.

If you look real close at the fuel lines (even under truck), fuel rails, the injectors, and the return system - including the purge canister and it's hoses - and do not see any leaks (when running) of raw fuel or see any holes in the vac hoses or hoses that are not connected I would fear the fuel you are smelling is because the computer is trying to compensate for the lack of hot burn in cylinders that are being contamiinated with water. As the truck runs the o2 sensor is reading bad numbers so it causes the computer to try and make changes or if the system is far enough out of range the computer goes into "Limp" mode which is very rich and destroys any thought of fuel economy. Try the spray for intake leak, do real detailed inspection of all fuel components and vac hoses (the spray will find breaks in hoses too as long as they happen to be turned on at the time, some are only on when activated by computer like EGR) and when cool check that radiator is full and mark the exact leval of coolant in tank with sharpie and after a drive and cool down again see if some is lost.

Did someone do a recent fuel filter, plugs, or any other work shortly before this started? The white smoke and misfire do sound like head gasket though and compression test would be a good test to see what you have for cylinder pressure.

 

White smoke could also be unburned fuel which would make sense because you have rich codes. You prob have a injector hanging open dumping fuel. Check the oil and see if it smells like gas. If it is dumping fuel then you need to not drive it until its fixed.

 

I would check the injectors for cyl 3&4 there has been problems with the injectors sticking open on these engines. I did a 5.4 for a friend and he had one stuck open. It actually made the engine hard to spin over at times. It is not hard to pull the injector rail up with the injectors attatched, then turn on the switch and if the injecto0r is stuck open it will be spraying fuel as long as there is pressure in the rail. The truck I did had cyl 3 injector stuck open.
I hope this helps.

 

I really hope you're wrong about the head, although I did have a vehicle tha had a bad gasket and it put out a ton of smoke/steam. From what I understand, to do the head requires pulling the engine. About a year ago I had a three car garage burn to the ground. I lost nearly all my tools, a completely rebuilt Goldwing, two vehicles, and a ton of other stuff, all uninsured. Any work I do now is under a small carport. I really hope it's something else.

 

You might be on to something. It was very hard to start the last time I started it. Almost like a hydrolock, the engine didn't want to turn over. It is really smelling of fuel when it's running. 70f100longbed is thinking the same way. As much smoke coming from it now, I quit driving it. I have a 96 Aspire with 160K and no equipment that i had to get plates, inspection, and a battery just to get to work. It's a pice of crap but it runs. I will check the oil and pull the injectors this weekend. If I disconnected the wires to the injector and it quit smoking that should tell me if they are the problem as well. Would this cause any other problems? I thank all of you for the tips, I let ya know what I find.

 

I'll check the oil this weekend. I did quit driving it, I don't want to change the O2 sensor unless I have to. This smoke definately stinks of fuel.

 

Jim disconnecting the harness from the injector won't make any difference if the injector is physically stuck open. If you lift the rail out of the intake with the injectors still in the fuel rail, just turn the key to on and the fuel pump will run for 3 seconds to pressure up the rail. If the injector is stuck open it will be spraying fuel.
Be sure to clean around the injectors at the intake before you pull them out, and put some grease on the o-rings before you push them back in.

 

Its also been stated on this site if the injector is stuck open it will mess up and flood the cats and they will need to be changed.

 

Just to let ya know, I pulled the injectors on Friday and number 4 never stopped spraying. Number three was good. I moved number4 to another location and it still sprayed. I figured if three was showing a misfire it probably will do it again so I’m going to replace it as well. I tried to get new ones at Autozone and Advanced but neither one carried them. I ordered them from Rockauto and they should be here today. Thanks again for the help. I posted this at another F150 forum, but never got a reply. I guess I got lucky finding this one. THANKS !!!

 

Change the oil before you start driving it again and cross your fingers the cat will be ok.

 

Good for you Jim, you need to watch that your cats did not get particially plugged from the raw fuel that pumped into the exhaust. What happens is that they will melt enough to restrict the exhaust. It will hurt your mileage, and make the truck "lazy" in real bad cases it can keep it from revving past a certian point, and make the engine overheat.
Good luck to ya.