Why does my truck go into limp mode?

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dodgediesel4x4

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Feb 15, 2010
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Every time I give it WOT and run a few seconds at it, the overhead console reads "service soon, see dealer now" stuff. The CEL doesnt come on, just the overhead beeps at me and the truck loses all power and goes into limp mode.
I bipassed the egr and did a delete pipe ("california-style delete) and am using a Smarty-jr to be running code free. The only way to get the truck outta limp mode is to clear the codes (even though none pop up after going into limp mode) with the Smarty jr and the truck runs fine, until I go WOT.

I read earlier on a few posts something about shimming the rail valve, but did a search and didnt come up with much. Sorry, I'm not too familiar w/ the 6.7 yet, still learning, feel bad about asking such a rookie question, but cant find any answers anywhere else. Just trying to figure out my problem. I don't have gauges yet (I know, Im working on that) so seeing if yall can help me out in any way. Thanks
 
ive had that befor at the drag track but i got a code it was the crank case breather filter and they are not cheap about 140 bucks i wonder if you can bypass that filter
 
Still no codes pop up when this happens. Im getting pretty sick of this happening everytime I want to pass somebody...Any ideas guys?
 
dodgediesel4x4 said:
Every time I give it WOT and run a few seconds at it, the overhead console reads "service soon, see dealer now" stuff. The CEL doesnt come on, just the overhead beeps at me and the truck loses all power and goes into limp mode.
I bipassed the egr and did a delete pipe ("california-style delete) and am using a Smarty-jr to be running code free. The only way to get the truck outta limp mode is to clear the codes (even though none pop up after going into limp mode) with the Smarty jr and the truck runs fine, until I go WOT.

I read earlier on a few posts something about shimming the rail valve, but did a search and didnt come up with much. Sorry, I'm not too familiar w/ the 6.7 yet, still learning, feel bad about asking such a rookie question, but cant find any answers anywhere else. Just trying to figure out my problem. I don't have gauges yet (I know, Im working on that) so seeing if yall can help me out in any way. Thanks
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I haven't had any problems out of mine, so can't help you there. But I can answer the fuel rail plug/shim questions. Your stock fuel rail has a valve/plug on the end of it (Towards the front of the truck..). It is set by the factory to pop off or open (however you want to look at it) at a certain pressure. This works fine for the stock hp/fuel requirements of the truck. But when you add the smarty or any other programmer where fuel is increased, you run into a problem. Now I've heard that you have to plug it or that you have to shim it. It seems that alot of guys are very set on one way. Not so much on CompD, but big time on CF. If you plug it, then that's it. If you have a spike of pressure you can probably say goodby to a piston/injector. Something in that area... If you shim it, you are basically raising the pressure level at which it pops... (Forgot to say that when it opens, its just returning fuel back to the system and away from your injectors... ) With that said, I don't recall ever hearing anyone saying to leave it stock on the 07.5-09's... You need a guage... that would tell us what your pressure is and either eliminate that as the problem or solved... Kind of hard to guess at this stuff. I don't know anything about the smarty, but it doesn't have guages right?? If that's the case you probably should turn it off (LIKE RIGHT NOW). Get some guages (Boost 0-100 psi, Drive Pressue, EGT, Fuel Rail Pressure). That would be a great place to start. Your going to end up breaking something if you can't see what's going on. Just my oppinion. Oh and mine's plugged, haven't seen a spike above 28,000.
 
you can pick one of those filters up wayy cheaper than the dealer. go to Genos garage. they sell them. and i will agree with DaveMatthews, it is more than likely your fuel rail popoff. mine did the same thing to me. and finally after 3 or 4 times, it set a code saying that it had popped open. i went ahead and plugged mine for the time being, until i can get aholt of the special nut it takes to pull the relief valve apart.. then after that, i will go the shim route...
 
Just plug it that's what I did. Ppe makes a race plug. It's real easy
 
Well still having the same propblem, but now I get the code P2227 barometric pressure...blah blah. What does this mean? Is this the wiring harness that is on the stock air box (Which I still have)? Can I just bypass/ delete this? Thanks for the info guys!
 
dodgediesel4x4 said:
Well still having the same propblem, but now I get the code P2227 barometric pressure...blah blah. What does this mean? Is this the wiring harness that is on the stock air box (Which I still have)? Can I just bypass/ delete this? Thanks for the info guys!
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EEWW. Waiting for an actual knowledgeable cummins guy to chim in and help you. Cuz I have no clue. What about smarty, have you called them? :redx:
 
sounds like either the MAP sensor is unplugged, bad or needs cleaned. Drivers side on the intake horn back side facing the firewall, Little 1" square black sensor with a single torx screw holding it in. take the screw out and genlty twist back and forth while pulling outward on it (it has an oring on the inside that seals it) just be gentle and it will twist right out. take that and clean it with NON chlorinated brake cleaner and put it back in and plug everything back up. They fill up with carbon and the truck cant read Manifold Pressure so it doesnt know what fuel mixture to run and will throw you into limp mode every time.

Are you running any kind of tuner?
 
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weazel said:
Do you have something unplugged somewhere?
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Not that I know of. When I did my delete (partial delete, more like a disable) my truck did not have a egr cooler. Its a c&c and thats a whole nother ball game. The instructions that I read said to "unplug egr cooler servo." I couldn't find this servo because there is no egr cooler on my truck (I uploaded pics on another website and no one could point out the cooler). I dont think this is what is causing my problem because this started happening before I did this delete.

Infact, I thought it was the dpf that was clogged (even though no overhead display or codes popped up) so thats why I did the delete. This is also why I dont think it has anything to do with the Smarty. I haven't removed the Smarty and tried it without it because the truck will throw codes and CEL if I do so, but if it was doing it prior, shouldnt matter anyway.
 
rbmedic75 said:
sounds like either the MAP sensor is unplugged, bad or needs cleaned. Drivers side on the intake horn back side facing the firewall, Little 1" square black sensor with a single torx screw holding it in. take the screw out and genlty twist back and forth while pulling outward on it (it has an oring on the inside that seals it) just be gentle and it will twist right out. take that and clean it with NON chlorinated brake cleaner and put it back in and plug everything back up. They fill up with carbon and the truck cant read Manifold Pressure so it doesnt know what fuel mixture to run and will throw you into limp mode every time.

Are you running any kind of tuner?
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Thanks, I'll try that and see if it helps.

Yes, I'm running a Smarty Jr ME version, which lets the truck run code free after the deletes.
 
Ok make sure the MAP sensor is plugged in, I have had several guys unplug it by mistake. If its either broken or needs cleaned. What was the mileage when you deleted? here is a good pic another compd memeber posted up of a NON deleted truck

gridb4after.jpg


MAP sensor get the same crap on it
 
yeah and the not so cool part is its CARBON which under extreme heat and pressure makes DIAMONDS. granted we are not making diamonds but I have seen it crystalize into very hard coarse littlepieces that I sure the cylinder walls LOVE when they break loose and get sucked through the valves
 
Not sure on the C&C but did you unplug the throttle valve on the bottom on the intake horn? I have never heard of that one throwing you into limp mode but it can definitely make the motor fall on its face. The one and only time I popped the fuel rail valve it immediately gave a CEL.
 
shoot you have a C&C the MAP sensor is in a different place its not in the intake horn. Sorry about that didnt catch that in your signature. Still the most likely problem. Any update?
 
Sorry, havent had time to locate/clean the map sensor. Any idea where it is since you realized I have a c&c?
 
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