Ok, the final remaining issue with my truck has been a real head scratcher. I've done so much to fix this thing, and I am still having the original problem, although I've fixed so many other obvious issues.

F150, 302 V8 (5.0L)

Truck has brand new exhaust, including the cat, from the engine back. Old o2 sensor was jet black and one side even looked crunched in a bit, so I replaced that. EGR valve was blocked and not opening, so i threw in a brand new EGR. Swapped in new FPR, and MAP sensor. I have also ran Lucas Oil injector cleaner. My next culprit is a temp sensor, but i thought I'd check here first for suggestions:

Symptoms:
-VERY hot exhaust, so hot it already wrecked the brand new hangar on the tailpipe, and heats up the cab pretty good too. Can't even put hand within 1 ft of fumes from tailpipe when engine is warm, it's HOT
-Thin white smoke from exhaust when engine is cold, and also when hot and under a load. Smoke is not sweet, truck shows no signs of bad head/head gasket, and does not smell like oil or gas, no more scent than regular exhaust fumes, just heavier smell
-Idles fine @ about 700RPM, but when pulling up to a light or any other stop, it takes it about 30 sec to a min to drop down there from about 1100 RPM
-Inside of 5 day old tailpipe is already very black

After failing E-Check for high hydrocarbons and CO2, it got real hot, luckily I found a parking lot and let it cool before it got TOO hot, and it was hard to start, idled real rough and low until i stabbed the throttle real quick then it came back, but that has only happened once.

 

What codes are you getting?

The hard starting when hot and high HC on the sniffer test suggests it's running rich. Possible causes are a leaking fuel injector, fuel pressure too high(should be 38-45psi max), flooded fuel tank vapor system due to fuel tank crossflow problem, or a sensor porblem. The high idle could be a vacuum or gasket leak but it could also just be a sticky throttle cable or heavily worn throttbody, or it could be a sticking IAC valve or bad TPS sensor. Pull codes first if nothing else that will eliminate a bunch of possibilities.

 

Prior to changing the EGR and o2 sensors I got these:

33-EGR not opening
41-System lean
95-Air/fuel mix off

I have not been able to get it tested after fixing these issues though

 

What year is this truck? For 2 digit codes it should be pre '92 but there are exceptions. Are you using a code reader to pull codes or flashing them on the check engine light?

Have you cleared the old codes to see if any still come back?

 

I have no idea if they are back yet, the CEL is gone/burnt out, and the only AutoZone that will do this test (they're actually not allowed) is a 1/2 hour from me. He plugged a little box with a flashing light that beeped into the receptacle under my hood and it flashed out the code.

It is a '93.

I will be trying PCV valve tomorrow, and intake air temp sensor, also wondering if it is all just a timing issue, but I have no timing light so i have no clue if that is it

 

Sounds like you didn't take the time to clean the old injectors, just running a bottle thru the tank will not clean injectors. Remove them, energize each one ( one at a time) and spray carb cleaner thru them, spray it til you see the stuff coming out of the tip, then follow up with compressed air. I've done it like this on more than a few EFI 302's and 351's and always come up with a dead injector or two and more than a few that are simply gunked up. When you energize them, you will hear em click. No click = dead injector. Good time to install fresh O rings on them too. You can buy these at the parts house. I use a 12V battery charger to energize them. Two spade terminals on each, one is positive, one negative, makes no difference which is which to clean them.

 

Also check to make sure all the spark plugs are firing. Of course, if there was a leaking injector, a plug would be pretty fouled by now, so you can check for that as well.

I once caught the carpet on fire in a test car because the catalytic converter got so hot, because it got too much unburnt fuel combined with lots of air from the AIR system, because 3 of the plugs were not firing consistently. The mechanic said it was working fine before it was put away a couple months earlier.

I've done a cheap trick to clean the injectors. I got the host off of one of those fix-a-flat spray cans for its Schrader fitting, and found a can of carb/injector cleaner with a top that matched the spray head of the fixer hose. I removed the core of the Schrader valve on the fuel rail and attached the fitting from the fixer hose to it (remove any rubber gasket from the fitting first; it will not stand up to the cleaner solution). I disabled the fuel pump on the car, and used the cleaner to pressurize the rail, and started the engine and got it running on the cleaning fluid. To be thorough, run about half a can through the engine that way, and it does a good job cleaning out the injectors.

If you go the route that Baddad suggested (I have as well), you want to also spray from the tip backward through the injector inlet to flush out anything that might have gotten caught by its internal mesh. I used a small 12v battery to energize the injectors. Obviously, you have to remove the injectors first, which means removing the intake manifolds first.

 

I have had the thought that it could be injectors, but I am really kind of saving that for a last step. My funds are now very low, as I sit here waiting to receive the start date for my new job, and I really only have basic mechanic skills, so this seems a bit tough for me :/

I do thank all of you for your advice and help, it means a lot to me that strangers are willing to help me figure this thing out!

My thoughts for the other two parts could solve the issue in a two-step kind of way, which is why I will be trying them first, also, because they are easier and cheaper than injectors!

PCV valve would explain the odd/slow idle, and the smoke. To my knowledge i it is not working properly, it would encourage the engine to consume oil, which would be burnt up and make the smoke and black residue.

The intake air temp sensor may be bad and making the thing think it is running cold, which would explain why everything is getting so hot.

At least, these are my hopes! Two bad parts would also equal this combination of issues. If not the temp sensor, then maybe my timing is off, causing a lean condition, which would also make for a very warm running vehicle.

If none of these work, then it is on to the injectors, but, if one or more are dead, I will have to wait 2-3 weeks until I get that first pay check...

 

So you haven't pulled codes yourself. It couldn't be much easier as long as the check engine light on the dash isn't burned out, if it is then replacing the bulb should be your first job. That is not that hard just remove the trim around the dash cluster and unbolt the cluster and pull it out, the bulbs insert from the back.

Then pulling codes is simple, put a jumper wire between the STI and SIG_RTN wires in the EEC test harness under the hood, turn the key to run and count the flashes on the check engine light. Lots more info on this here.. Fuel Injection Technical Library » How To Run a Self-Test

 

I've already posted what codes it threw, and I am having a hard time seeing where doing it again would be beneficial. It is still having the exact same issue as before, likely minus the EGR code now, and given how vague the results are anyways it seems to me like it would be akin to staring at a magic 8 ball. I know what the truck is doing wrong, I am just trying to narrow down how to stop it from doing this, and have solved many issues along the way. If I pull the codes, and it tells me the same things, likely, since it's still the same exact problem, then I've done nothing but spent time recycling the past. This is not a 2013, where pulling a code will tell me practically everything i need to know. It's an OBD1.

 

That's because you're not utilizing it correctly. Codes are stored and they never go away unless they're cleared. If you do that(disconnect battery for 10 minutes), drive for a few days and pull them again you will know if you have fixed a problem or not. No this old system doesn't give you as much info as the newer cars but using it is better than blindly throwing money and parts at it.

 

You don't need to remove the intake to pull the injectors, only the upper half. Once that's out of the way, remove the fuel rail and pull the injectors out.

 

These two tell me that you've got dirty injectors. Or possibly have a few dead ones. Some are lean, some are rich. Reading the spark plugs will also tell you the same thing. Starting it up and feeling them will tell you if you have dead injectors, you can feel them clicking if they're working. (Or at least the ones you can get to)

 

Then i will be feeling the injectors today once i do a bit more to it, got me a new PVC valve and intake air sensor. Even if I am "blindly throwing parts at it", I will know for sure that those parts are all brand new and no need to bother with them. Besides, while the issue is still not resolved, everything I've done to it was certainly bad to begin with. Not once so far have I replaced a part that was still in working order

 

Well, I could feel all but one injector, and they were all ticking away, but that still doesn't mean that it doesn't have one or more that aren't opening all the way, or could be clogged. Just going to go get some "new" ones from the local DIY junkyard for $7 a piece, test them each and buy a new o-ring set and see what happens. Won't set me back but $60 or so, worth a shot