Then what would the computer try to do to compensate? Would it try and shorten the PWM on the other injectors to keep the A/F ratio correct? This would result in a loss of power to an extent due to one cylinder being more powerful than the others.

Does this sound right?

 

The way the engine ECM can tell if a cylinder is over fueling is by processing difference in acceleration speeds between cylinder fires. If one injcetor is "dripping" or and adding extra fuel to make that cylinder output more, then the ECM, using the crank sensor, can calculate the acceleration rate of the crankshaft at that moment and compare it to other cylinders and the acceleration of the crank at those moments.

The problem is that a dripping fuel injector tends to not create the atomized spray pattern, because it is damaged, hence the dripping. So even though it may be putting extra fuel into the cylinder, it may not be burning it because it is not correctly atomized to burn in the combustion chamber. SO that cylinder may contribute less.

There are contribution codes that store in the ECM for instances where a cylinder (or more than one cylinder), that is over or under contributing, will be noticed after a certain threshold has been obtained in order for the ECM to set a code and illuminate the engine lamp.

I only know of one diesel engine that uses an O2 sensor to measure air/fuel ratio. Does the Ford measure that with an O2 sensor?

So I think it is possible for a dripping injector to become apparent to the ECM that there is a contribution problem. But how badly does it have to leak to know? It's bad enough when the ECM says it is, which is usually before you can feel the difference in the seat of your pants.

 

If it was bad enough or the contribution was way off then it will throw a code. If it is dripping or the lines were leaking then no code. As long as there is correct pressure from the pump no code.

 

Yeah, I only meant that it would be nice to have the ability for the computer, with all it's sensors, to be able to DETECt the leaking injector, not necessarily be able to compensate for it. Thats way beyond my knowledge. You would think there would be that ability built in is all.

 

i have too take mine in this week, black smoke on take off and going up hills hard. service manager thinks the egr valve is bad. hope this fixs my problem, maybe yours too.

 

Not if there is fuel in the oil.

If you are only having the black pipes then perhaps.

 

Yep, and any unburnt fuel will exit post-haste in a black cloud.

 

Just throwing a few questions out here to try and make some sense of all of this. You bought the truck used with 49K on it. Do you know if the truck was ever modified or tuned (i.e. DPF delete etc...) and then put back to stock prior to selling it? This could be the source of the sooty tail pipe....Second, if you are currently seeing black smoke out of the pipe, than there is something wrong with the DPF filter. It should not allow any soot past the filter medium period. If it does, it is broken. I would threaten your Ford dealer and tell them that you are going to report them to the EPA for neglecting an obvious emissions violation if they do not figure out the cause of the smoke as it obviously is not within the EPA emissions guidelines for this model year. I bet that will stir some activity with the service dept. management. They could easily justify replacing the DPF under warranty. A cracked DPF filter will not typically trip a code anyhow....

 

Not sure if it was chipped or not. There are no obvious holes in the dash for switches, etc... Dealer has never doubted the validity of the warranty.

It had been to the dealer numerous times for different repairs since it is a Job 1 truck. I did not see any mention of it in the OASIS report that came back on the truck.

As far as I can tell I can't see any cracks or poor fitting pipes. But then again you really can't see all that well under the hood to begin with. I do recall someone mentioning cracked downpipes on some trucks. I'll have to crawl under there again and look real good.

It doesn't roll black smoke like a chipped truck would. Just a little puff from a start a few days ago. Didn't do it today at all. It will let out slight haze that can be seen at night in the headlights of the car behind me. But that's only if I roll into it and floor it.

But I can clean the tailpipe and it will be black within a week!

 

I'd be wondering about a dripping injector....not enough to trigger a compression imbalance, but enough to give you the smoke. Do you run any additives like Diesel Kleen? No, I'm not a sponsor of them, but I believe in it like I believe in Techron in my gasser.

 

Yep. That or the Motorcraft stuff.

 

now I'm not sayingthereisn't another problem such as the injector issue that you are referring to, but it still shouldn't show any visible signs of smoke. If you clean the pipe and it soots up again rather quickly, I would bet you have a cracked DPF filter. You can't see the crack as it will be internal to the cannister and will allow the soot to pass thru the crack....

 

I was thinking the crack would be on the outside and would allow either air into it or exhaust out of it and mess with the cleaning process.

 

we are talking about a very small crack to allow soot particles thru.. maybe not visible to the naked eye..

Sam

 

Hello all, maybe from a different situation but on my 98 expedition, I had a black tailpipe and it was from a running lean problem. It was fixed by an auto shop that did a scan on it and found that both the o2 sensor and the MAF was bad. It ran good through the city with out noticing it but on the highway you would here an occasional pinging, especially when going uphill or passing.