[isaiahfronning]

I have a 2002 F250 7.3. Yesterday I was driving away from a stop sign, softly accelerating, and all of a sudden a crap load of smoke started billowing out the tailpipe and a knocking sound started on the top end on the passenger side. My injectors have been going bad for a while, I just haven't had the funds to replace all of them. I don't think it's a valve because it's all diesel smoke and crank case pressure is normal, it doesn't putt putt at all, oil pressure is normal, and the knocking sound doesn't always occur if I let it sit for a few minutes and then restart it, but after running for a few seconds it starts again. I had my ICP sensor come loose and leak out 2 1/2 gallons of oil and shut the truck off, so the injectors might have heated up from lack of oil. Is this most likely an injector or something more serious?

 

[sbluke55]

I would start by ohming out the uvch's and check the 42 pin connector on the drivers valve cover. It tends to chafe the harness from the computer.

 

[isaiahfronning]

Here's a little update, it's about 8 degrees outside so I haven't taken anything apart on it, but I notice there's a nice leak on the passenger side up-pipe to the turbo, which is billowing out smoke and might explain the loud noise on that side that isn't always noticeable. It also feels like it is slightly hydrolocked on one cylinder when cold but after a few cranks it clears up. Is it possible it's leaking so bad it's messing with the PCM and telling it do deliver more fuel than it should? It started like a champ of course when I'm not going to drive it. Here's a video of it.

 

[greenskeeper]

sticking injector is a possibility or something mechanically wrong with a cylinder or two.

my steps going forward would be to remove the valve covers and check for oil at each injector spout. Then one at a time disconnect the pigtail to each injector and see if the smoking/knocking stops, if so you've found the bad hole.

 

[isaiahfronning]

Here's another update,
I got the valve covers off today and unplugged each injector one at a time. It still smoked no matter what and I notice it has a definite skip in it when cranking. But if the injector is stuck open and just dumping fuel into the cylinder would it even make a difference? It's gone through 1/4 tank of fuel just from idling a total of about 30 minutes. I notice one side of the engine smells like un-burnt fuel. I don't know if this would make any difference, but I notice it has AC injectors when I assume it should have AD. Any ideas? I'm hoping I won't have to rebuild this engine, even though I should with 304,000 miles on it.

 

[isaiahfronning]

I noticed today when I had time to work on the truck that on the #8 injector when unplugged emitted much less smoke. When #8 was plugged in and any other injector was unplugged, it put out just as much smoke as when all 8 were plugged in. I would assume the plunger inside the #8 injector is sticking slightly open allowing fuel to go into the cylinder even when unplugged. I left said injector unplugged overnight and I noticed I didn't have a problem of it seeming hydro-locked, until #8 was plugged back in and I shut the truck off. Am I on the correct track by assuming the #8 injetor is bad? My elm327 bluetooth adapter decided it doesn't want to work anymore so as of right now I have no way of buzz testing the injectors. Here's a video showing it unplugged versus plugged. The video starts out unplugged.

 

[greenskeeper]

The smoking is "reduced" when #8 is unplugged, but it's still smoking a ton.

When the truck is at operating temperature does smoke stop? Reduce significantly?

Might want to do a compression test before installing new injectors. How much blow by out the oil cap? Will the cap rest on the filler neck or get blow off?

 

[isaiahfronning]

The smoking is "reduced" when #8 is unplugged, but it's still smoking a ton.

When the truck is at operating temperature does smoke stop? Reduce significantly?

Might want to do a compression test before installing new injectors. How much blow by out the oil cap? Will the cap rest on the filler neck or get blow off?

When it warms up it the smoke reduces a little, but not much. The first thing I checked was blow-by when this happened, and there's a little smoke, but no more than it's had since I've had it. There's hardly any pressure at all when I put my hand on the oil spout, so little I can hardly say there is any noticeable pressure, and the oil cap won't even move a hair when set loose on the spout. There's no oil burning, it's all diesel smoke. I'm guessing the plunger which is pressed down by the high pressure oil inside the injector is stuck slightly down at all times, forcing the nozzle needle to be slightly lifted and therefore allowing the fuel inlet to flow directly into the cylinder at all times, whether or not the injector is pulsing. I might just purchase a used #8 injector from ebay for 50 bucks and if that eliminates the smoke I would replace all 8. Would this be a reasonable course of action to take?

 

[greenskeeper]

If it was my truck I'd do a compression test first to see the condition of the engine with 300k miles on it. If all checks out then I would replace the injectors.