I have a question about this OBDII code, and what it might mean on my Cummins turbo diesel.

I know the code has to do with a fuel rail sensor and the range/performance of it. But what exactly does that mean, and what does it mean as to what is likely going on? The check engine light does NOT come on (other then during the startup "test"), but this code is stored in the computer.

I purchased my 2004 Dodge 3500 CTD less then a week ago, and it was already highly modified (after having a 1997 Dodge 1500 V8 for about 7 years, and a 2000 ford powerstroke for a couple weeks). The engine runs great, and I love it. BUT, and don't hate me for this, I want to reduce the amount of black smoke that comes out of it under more then light acceleration. I want the truck to look tough, be as tough as the original engine, but after that I want to mpg to be as high as possible, and I don't want to have to worry about the EGT's (I do have a pyrometer, but I don't want to take any more chances then necessary). Soooooo, I'm looking into what I can change.

As I mentioned, there is that code.

Also, the fuel delivery system has been modified slightly -- there are two fuel filters (but neither appear to remove water) added near the fuel tank, and the original fuel filter/water seperator is taken out of the loop completely. I realize that this would be difficult for anyone to answer without seeing it, but can anyone think of a reason why I couldn't keep the two fuel filters, and just put the original fuel filter/water seperator back into the loop? (I'd feel "safer" with a water seperator still in the loop. Plus, other then possibly making more fuel flow restrictions, I don't see any problem... And since it seems to be getting to much fuel anyway (black smoke), I don't think that's of much concern)

On the exhaust side of things, there are two sensors just past the exhaust manifold. I assume, at this point, they are oxygen sensors (?). But one of the sensors (the one farthest towards the passenger side) has it's cable cut off and is not connected to anything. (The other sensor I assume is still connected, but I haven't actually followed it's cabling to it's end yet). First, if one isn't even connected, why isn't a code coming up in the computer? And two, where is it supposed to be connected?

Aside from those items, I don't KNOW of anything else that could be causing the block smoke. What else should I be looking for?

And finally, what is a good repair book to purchase for a 2004 Dodge 3500 CTD?

Thank you.

 

Attached is the information about code P0191. It's from the 2005 service manual, because the 2004 doesn't seem to have explinations for the DTCs in it.
As far as a good repair book: go here and look on the left, and pick your year (actually, if your not 56K, I would download other years as well, because as stated, for some reason the 2004 manual does not have the DTC's in it, while the 2005 does). They are big downloads, but they are more than worth it!

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sounds like a FASS I or air dog system has been installed on the truck, it will remove water and filter the fuel better than what the stock filter can do.

now when you say the truck has been modified, what else has been added, it sounds like a downlaoder of a box is on this truck. any time you add power to the engine, your gunna get more smoke. take the downloader off and the smoke will go down.

 

Another place to try for the manual that is an easier download, is
http://www.dodge.com/bodybuilder
Click on the year of the truck on the left margin.

As for the code, I have had that code three times since I got my 05 last March.
First time, the sensor was replaced, second and third time, they just reset and cleared the code.
They claim that DC is aware of this prob and they are working on a cure but none yet.

 

Wow, thanks for the good info so fast!

I'm downloading the manuals as we "speak" (2004 and 2005. Worth doing more?)

I checked, online, and it appears that you are right Drew -- the fuel system filter/etc looks like a FASS system. EXCEPT I don't believe there is any drain or anything on what is supposed to be the seperator -- I'll have to check on that yet to be sure though (but I specifically looked for one before). Does the FASS system, as supposed to be installed at least, auto drain the water, or is it a manual operation? And if it's a manual operation, how do you know when it's needed?

 

dont hold me to this, but I think one filter is for water seperation only, and the other is for dirt/muck.

as long as you are choosy about where you get your fuel you shouldnt have a problem with water in the tank. I only get my diesel from high volume suppliers, 35K and still no H2O.

changeing the filters is a bit different on the FASS and you can actualy go longer between changes. Atleast you wont be running low on fuel pressure any time soon with that FASS installed.

 

Well, the way the original owner has it, it appears that both filters are just that, filters. No water seperation... But obviously, I could just change one of the filters back to a water seperator.

But if I wanted to be wierd, do you see a problem just putting the original filter/water seperator back into the loop? I don't think an extra filter is a bad idea. (Besides, I MIGHT be trying making my own biodiesel, and extra filters are allways good in that case I would say... )

As for the downloader.... Where would I find it? I would have assumed on the ECM, but it doesn't appear to have anything there. Any other ideas?

Thanks.

 

The sensors are / were more than likely for an EGT (exhuast gas temp) guage.

 

Yea, I figured that out after I followed the wires around.

But why is there a second one not connected to anything? (one is connected to the pyrometer)

Thanks.

 

the extra pyro might have been from him stacking boxes, you can run two boxes off of one pyro, but the temps might be a bit off due to voltage differences.

you can hook the origional filter up, it wont hurt a thing, just make sure you are not trying to push through the stock lift pump if it is still there.