[jas10]

My (to my knowledge) non-chipped 02 w/ 68k miles puts out a fair amount of black smoke if I lug it while climbing a hill. Is this normal? Once I get RPMs up to 1700 or so the smoke goes away. It's not like I'm leaving a big black cloud behind me, but I can watch it smoke pretty good out my passenger mirror. None of the diesels I've owned smoked at all but none of them had more than 30k miles on them.

Main reason I'm interested is because I say my truck is not chipped, but I actually haven't inspected the PCM. I tried to look at it today but I didn't have time. I have quite a bit of noticeable spark knock type noise too so I'm wondering if the black smoke and the ping sound might indicate advanced timing.

I don't have my boost guage yet so I'm in the dark as to what kind of boost #s I'm getting. My power is good and I hear the turbo spool and whistle good once I get moving up a hill so I don't think I'm having any problems with the turbo.

-john

 

[jas10]

Ok, I pulled my PCM and I'm convinced the truck has never been chipped and I'd be very surprised if it's had any programming.

So this is a completely stock motor. What all could cause black smoke.

* Intercooler leaks
* Turbo problem
* Dirty injectors

What else? And what's a good plan for isolating the root cause?

Thanks,
-john

 

[kainers]

dirty air filter.Stuck injector.It will rattle real bad if a injector is not fireing correctly.My wifes did it this morning.Ran it out of fuel.

Low compression dusted motor all sorts could proabably cause it.Start with the basics.Air filter, Injector cleaner, boost leaks.

Mike

 

[jas10]

Brand new AIS, so air filter is good.

Not dusted. Had a crankcase pressure test and the motor's tight. Tech ran the test twice and could only get about 3/4 inch or water.

What does the rattle sound like if an injector is bad? I have a pinging noise under load that sounds just like spark knock. It's worse in the cackle RPM range but even at higher RPMs it's there. The motor idles and runs smooth though, it's just noisy.

-john

 

[kainers]

spark knock idle knock.Some where in my webshots shows the heat exchanger in the fuel tank full of grime.I pulled it out got rid of the knock for awhile.I never had excessive smoke though.

I would just run some diesel injector cleaner through it and see what happens.Won't hurt nothing just make sure it is diesel injector cleaner not gas.

MIke

 

[T_Bone]

Hi John,

You discribing two different problems.

First your adding to much fuel to quick in too high of a gear thus your here what you reffer to as spark knock. If you read Fords explantion of lugging then you will see your close to lugging the engine when this happpens. If you want to gain speed quicky, drop down a gear then acellerate. Remember a diesel is not like a gasser as a diesel needs time to wind up to a higher rpm.

Another cause is a suction air leak. The most likely place is the QD on the fuel pump suction fitting. Just replace this with a 8" long piece of 5/16" fuel line with double hose clamp on both ends.


Below is what Ford says about engine lugging in the F650/750 owners manual:

"Excessive full throttle operation below peak torque RPM will shorten engine life to overhaul and can cause serious engine damage. Operation of the engine below peak torque RPM can occur during gear shifting due to difference of gear ratios."


Second is the black smoke. I get this as I shift at low rpm to obtain maximum fuel mileage even while pulling loads. I add fuel slowly and shift at 1250rpm on flat roads thus yield great fuel mileage. 19.2mpg empty, 14.1mpg pulling 16kGCW and 17.1mpg 15k lifetime fuel mileage with pulling 16kGCW for 6k miles.

After driving with this style the Cat loads with carbon as well as the pistons and valves, so once a month I take it out on the freeway then drop down a couple gears to 2800rpm for about 15sec and during this time I will belch black smoke then it will clear to a light grey color and I'm good for another month of light grey exhaust.




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[jas10]

T-Bone,
I already pulled the QD off and replaced it. I didn't notice any difference. The spark knock sound I get isn't related to lugging. It comes on strongest in 2nd and 3rd gear at about 1600 RPM (e.g. the cackle band), but I can still hear it up around 2k RPM too. I'm pretty light on the throttle and take my time getting the RPMs up. This is my first 7.3L so maybe this is just normal injector rattle, but I want to be sure.
-john

 

[T_Bone]

Hi John,

The first thing I would do is check for a suction air leak. Add a piece of clear tube to the filter drain, then idle engine, open filter drain, then observe fuel stream for air bubbles. Do NOT raise the engine rpm above idle rpm with the filter drain open.

The fuel pump will pump about 1gpm of extra fuel at idle, so be preparred.



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