I'm a geek and a 7.3 Excursion owner. That combination means I want to know as much as I can about my rig, how it operates and what is within spec. I got my truck, first diesel, back in May and started learning soon after.
<O</O

Brief History: I have AE and I've rebuilt/replaced: HPOP, Turbo, 6637, Up Pipes, Exhaust 4", Batteries, Starter, #3 injector, Valve cover gaskets, UVCH's, ICP Sensor, CPS. The truck has a stock (turbo & injectors)

<O</OAE: consistent IDM code (P1316), Buzz Test is good but says #8 is having issue. Cylinder Contribution Test comes back all good, PREDELS all register under 1 except #3 & #4 which reach a max of 1.9. Glow plug test is good. Rich says my Injector Pulse Bandwidth is a little more than normal, but after reviewing my data says the truck is in good health.

<O</OI'm trying to understand the smoke I get at different times… The tuck starts up just fine in cold (9*) or warm. I can plug in the truck and it might start with a few less rotations, but it's good. Idle is good. Truck runs great.

<O</OMorning starts with a puff of white smoke once the truck starts regardless of outside temp. If I didn't plug it in, I get about 60 secs of chugging white smoke and then it clears up to be faint but it remains. I’ll see faint smoke when I pull up to a stop light or when I just let the truck idle. Driving down the road under normal conditions I do not see excessive smoke from the tail pipe, however when I look at the back of the truck, I see soot build up on the rear quarter panel and edge of the bumper.

<O</OWhen I slam on the skinny pedal, I get some smoke out of the tail pipe with the RPM’s up. Previously I had a Super Chips on the truck and the smoke was black at WOT. I want to understand this smoke and understand it in relation to the health of the truck. I can’t clearly make out the color of what comes out.

<O</OI’ve checked blow-by using the oil cap upside down. It does not blow off, however the motor vibration wiggles it off. I have checked and confirmed my oil level isn’t going down as well as my antifreeze levels are remaining good.

<O</OAgain the truck runs wonderful, without issue. There are so many different colors of exhaust, what do they mean?

<O</OCan anyone help me with the different smells of the exhaust. I’ve confirmed I don’t have an exhaust leak, but when the truck idles, the exhaust smell can get strong down wind. The truck really puts out some exhaust. Is this normal? Newer diesels don’t seem to have such a prominent exhaust smell, is this just part of the 7.3?<O</O

 

First thanks for all the info! Give us more to chew on. Or in my case, maybe too much. Lemme throw some stuff out there...


Why?

Apologies for picking nits, but the buzz test "says" nothing. You hear the buzz and judge the sound. So the sound you hear from #8 is weak? If the PERDELS is showing a problem with 8, it always does, see this thread and chart.


White smoke is likely raw fuel, and will smell like it, which often points to glow plug issues, tho that tested good apparently. Possibly just tired injectors dribbling fuel when they shouldn't. Happens with miles and age. Ahem. Black smoke is unburnt fuel after a combustion event, with either too much fuel of not enough air. Same thing really, the air/fuel ratio is not optimal. Tunes (the Super Chips is a good example) will typically give black smoke as they increase fuel but cannot do a whole lot to increase air.

Given the P1316 I'd start by ohming the pins on the new UVCHs, see what is actually happening in there with the GPs and injectors. Here's an informative link of the subject.

And scads of info on the GP system. Might just be a clapped out relay.

You've got it tired and and on the ropes, a solid push and you'll get the problem outta there.
<o</o

 

Edit: ^^He types much faster than I do and has better answers! haha

I too would like to hear an "expert" explain the different types of smoke.

My truck does about the same as yours. When its cold 30* and below I get about a minute of white smoke if I don't plug it in, and nothing if I do. However the only smoke I ever get while driving is black, and that's at WOT.

What I know is the black smoke is just un-burnt fuel from a hard acceleration when boost is low....i.e. to much fuel and not enough air. Also on the same not white smoke can be un-burnt fuel under hard start conditions when the motor just isn't firing to burn the fuel at all. As for exhaust "smell" I'd say that is common with all of our trucks, not sure what exactly it is caused from but my truck has always done it weather its cold or warm outside, though it does seem to be a bit stronger when its warming up on a cold day but that may be from the high idle present when the truck is cold........on a total side not does anyone know what triggers the high idle? EOT? Outside Temp?

Sorry I kind of went off there, but that's my exhaust smoke knowledge.

 

I can tell you the high idle is the result of several factors including outside temp. I've deleted the EBPV, but it would be used during this process to warm up the motor. In my case, the motor just idles up to 1000 rpms until I either hit the break, or tap the skinny.

 

David,

#3 was replaced becasue it was throwing codes. A buzz test will initally just buzz the injectors, but will give you the specific codes stored in the IDM. I don't have the code in front of me, but it is a common one for only #8.

When monitoring the PREDELS, #8 does not create any alarms.

Excursions did not have a GPR, instead we have the California emmissions system so I can't do any more with that aside from replace it.

In addition to replacing all valve cover wiring, the GP's did OHM out under 1 so I have no reason to question them. I assume they might be getting weak....

The previous owner provided a reciept showing he had put a set of stock reman injectors in the truck last winter. After researching the company, it's a complete crap shoot as to how good the remans were.

I have been evaluating the possibility of swapping out the injectors myself so I know they are good, but that is just throuwing money at something that isn't a problem yet.

If the smoke I'm seeing is just unburt fuel, and doesn't pose any harm to my truck then AWESOME. I'll save some pennies and keep enjoying my turck until I need to do a swap. Being a new 7.3 owner, I'm just trying to learn as much as I can from the FTE brotherhood.

 

You might try swapping the injector or just the solenoid from #8 to another injector to see if the code follows or not... That would start to gather whether or not you need to dig deeper. Likely it is a code for high to low open, and can be caused by bad solenoids, poppet valve clearances, as well as other things. With regards to the smoke issue alone you could try unplugging #8 or building a breakout box to see if the smoke goes away when an injector is disabled.

 

Cloud Color Code

Black - That's soot from partially-burnt fuel. More air or less fueling is a common cure for this one. That being said, dribbling injector(s) can cause coal.

Blue - That's oil being burned. This could be a leaking bearing in a turbo sending oil straight to exhaust... so unlike a gasser, it doesn't immediately spell disaster.

White - This one's a little trickier... scent will tell you if it's fuel or coolant. Checking your degas bottle is another way to verify you're not sending scary steam out the pipe. White exhaust on a cold morning is very common. That's not saying you have a serious problem, it's saying there's not enough heat to light all the fuel. The difference between this and soot is there is fuel that didn't burn at all. While the Glow Plug system is a common culprit of white smoke at startup, lower (not low, just lower) compression of a high-mile engine can cause it as well. Fueling without firing has a feel to it (dead hole)... this will make plenty of "angel breath". Low Injector Control Pressure (reduced atomization) is another cause of white smoke. A retarded Start Of Injection in your tuning will also cause/augment this. Switching to synthetic 5-40 may give a measure of help with this, but no guarantees... it will certainly help with cold starts. White fuel smoke stinks, and an operating EBPV keeps this to a minimum, but welcome to the wonderful world of "classic" diesels.

The most common cause for caustic contamination? The owner. Many owners chip up, but don't really focus on how the truck breathes. Tuning is relatively convenient, compared to getting more air in there. Based on my experiments with Stinky and piles of AE data, I say a 4" exhaust and a proper Cold Air Intake is one of the best mods we can do for our vehicles. Think about it - really: As these trucks age, the compression drifts downward (increases smoke). What better compensation for cropped compression than more air going in the hole?

 

Those PERDELs are on par with off-the-shelf reman injectors. Roll with it until you feel the urge to get your geek going.

 

How does your air filter look? could be partially be the reason for your smoke. Is your turbo stock?

 

My 6637 is just a couple of months old and has been verified to be clean and free from obstructions. The turbo is stock with the exception of a RR 6/6 wheel.

 

O yeah, forgot it was an X with a GPCM. Same as my CA 02. That's good, since it will show specific codes for bad GPs or if the GPCM is bad. No codes = no problem. That said the two plugs on the GPCM can overheat, pull them off and check the male plastic plug for melting.

The P1316 keeps coming back for a reason. I associate it with UVCH, but it could be anywhere in the harness all the way back to the IDM. Easy to pop off the 42 pin connector and inspect the pins, check for chaffing of the wires on the valve cover. Check continuity of the injector wires from there to the VC plug. Preview the pinout pic Rich provided to FTE posterity.

Otherwise it does sound like tired injectors, but I'd really expect more than a year out of them, even if remans.

 

i have the same smoke issue, took a sniff of it....burned like hell, i think it smelled of unburnt fuel

 

Rich explained the colors very well. Classic diesels do stink more than modern diesels for a host of reasons. I put a turndown on my tailpipe to keep the soot off the box and bumper.
In the winter, your engine is pulling in huge amounts of very cold air. So cold that there is just not enough heat to ignite all the components of diesel fuel. The unburnt fuel causes the white smoke and eyeburning smell. It is normal for older non-emission engines. When your rpms increase, the faster compression generates more heat and the engine will run much cleaner.

 

whats the possibilities for "gray" smoke?

 

Thank you for clarifying this. I'm really learning as I go and I don't want to waste money on parts I don't need.

Having never been around diesels before I have no history to work from. I do know when it's cold the truck takes forever to warm up and will cool down quickly.

Should I put some sort if shroud behind the grill to restrict the air passage and keep the truck warmer like the big rigs do?