I attempted to hook up a trailer to my truck yesterday and found 2 wires were either cut or melted through. I didn't even attempt to splice them back together because there was no way to distinguish which wire was what color. They were all covered with soot. The entire rear underside of the bed is covered with a layer of soot.

What causes the engine to emit soot through the exhaust? As far as I know, it's been like this since I got the truck. The only code I have right now is one for the EGR temp sensor (and I'm almost positive it's a bad EGR temp sensor).

I'm running a 22re with california emissions. The only thing I can think of doing to remedy this is to replace the catalytic converter and oxygen sensor(s). Would that be a waste of time and money?

 

HUH? The entire underside of the bed is covered with soot? What about the front, is it clean?

If it is in fact soot, and only on the rear half, I would say you have a major exhaust leak, probably somewhere after the cat. Typically, a rich running condition will cause excess soot, or carbon build-up. However, a very lean running condition can also cause excess soot, but you would know it due to a lean misfire. This typically is not the cause.
If it is soot, it should wipe off fairly easily. At least off of slick surfaces like wire insulation.

The other thing I have to ask, is it really exhaust soot? Is there an oil leak somewhere that is blowing oil all over the underside? That oil could grab road grime and dust, and kind of look like soot. I don't think this is what is happening, but the condition does sound strange. I would think if this was the cause, it would be all over your axle, leaf springs, driveshaft, etc, and not just the underside of the bed.

Only other option that I can think of is the 'soot' is from the road itself, but then it would be on just about everything from behind the front tires and back.

Edited to add: Forgot to mention, I wouldn't replace anything without some diagnosis first. Only reason to replace the cat is if it's falling apart inside, clogged, or has a gaping hole in the side. I think you can check the O2 sensor resistance, maybe pull it out and do a visual on it. The FSM will tell you for sure.

If you want to check to see if it's running rich or lean, just pull the spark plugs and look at them. If they're really black and carboned up, it's rich. If they're white, it's lean, and if they're brown, it's just right.

If you can find an exhaust leak, then it might be time for a new exhaust and some headers! That is, if you don't already have them.

 

I'll start looking into the o2 sensor and an exhaust leak. The soot doesn't cover the entire underside, just from the muffler back. The previous owner cut the muffler short, so its only about half of the bed.

Last I checked the spark plugs, they were fine. Not too lean and not to rich. Not burning through much oil either. For 250k miles, it only goes through about a quart between changes.

 

What causes soot is unburnt gas its the same thing as diesel trucks that blow black smoke because they do not burn all of the fuel in the cylinder the best thing to do is to get finer injectors and hotter burning spark plugs would work and an over all engine clean would work to prevent some of that to air cleaner spark plugs, fuel filter and injector cleaner would help some

 

I've been using injector cleaner about every 500 to 1000 miles. And the spark plugs I use are typically just autolite brand. Which brand of plugs burn hotter than stock plugs?

 

NGK!

 

Yeah, you couldn't pay me to install anything but an NGK on my truck. I'm not sure on running the hotter plugs though. At least not on a stock setup.

 

you wouldn't want to run a hotter spark plug on a stock system my uncle runs them in his drag car with the 22re but i was running them in my 87 with the mustang motor i haven't ran them in my stock motor in my 85 haven't had a problem with the soot yet

 

Or is it dried up undercoating?

 

yes, dear god hotter plugs DO NOT give you more power...

And you've got an exhaust leak... It's not soot, which is very confusing. You have an exhaust leak that's RAPIDLY deteriorating the metal of your bed. And ???


GET ON THAT ASAP or I'll show you pics of what it will look like if you don't!

A dead bed... And they're not cheap, or plentiful...

 

LOL! Tried, maybe it's your avatar, but your postings crack me up. Keep them coming! BTW, who is that? I must be too young to know, although I should know anyway. Is he from the A-Team?