poor fuel mileage

[cum a long]

replaced 2003 ho cummins with a 2006 cummins. Fuel mileage went from 22 miles per gallon to 18 miles per gallon.Dealer claims the injectors need to be changed to injecters from 2003' The fuel injection shop says that the ecm controls the amount of fuel the engine requires and it was from the 2003 engine. Any advice would be appreciated.

 

[p-Bar]

Your 2003 was the best for power and mileage as Dodge went into the 04.5 year with the 600 motor along with that came a third injection event which helped keep the Cat hot for smog . Don't change the injectors unless they can prove they are bad. I think the spray pattern was different on the 03' too. Others will chime in with a lot more knowledge.

 

[jhenderson]

Run, don't walk away from that dealer. He's an idiot. Injection shop and p-Bar are right.

 

[rscurtis]

Unfortunately, you got rid of the best of the CR engines. A Rokktech crank sensor will help FE a little on the "600" engine. Unfortunately, it will never be as economical as the 305 engine, and you'll be spending a lot more on oil changes.

 

[Prairie Dog]

It's amazing how much dealers dont know sometimes.
Getting 18 out of your 06 tells me it's in good running order as many of them wont do that good. In fact a buddy of mine only has 22k on his and has never seen that kind of MPG.

Scott

 

[cum a long]

I'm a little confused your saying not to change the injectors yet the 03 injectors will work and may increase fuel milage

 

[cerberusiam]

I'm a little confused your saying not to change the injectors yet the 03 injectors will work and may increase fuel milage

Sorry, posted the wrong thought in the wrong thread. Again!!!

Yes, you can put the 03-04 injectors in the 600 series engines. I would not do that unless you can tweak the timing because you may NOT get better mileage beacuse of the hole configuration and size with the stock fuel maps. Stock to stock, the 600 series injectors run better than the 555 injectors as far as efficiency and power. Unless your 06 injectgors are bad I do not think you will gain anything without tuning.

Now, if you added 50 HP 143 angle injectors you MAY get better results without tuning. There is no good way to say what will happen because it is totally dependent on the vehicle and the driver.

In addition, the 143 injectors into the 600 pistons is iffy on where the heat soak is actually going to be. Too much around the outer edge of the 600 pistons and you have a potential problem.

Still really FUNNY a dealer is saying this because of the potential glitches that can happen. :-laf

A Smarty or EFI live on your 06 truck might do as much as any injector change, results vary. The 18 stock, if it is, is not bad for that truck. I think you can do better, just a choice of how to spend and where.

 

[cum a long]

I had a bulldog programmer on the 03 and truck was getting great fuel millage but when i tried to use it on the o6 it blows black smoke regardless of what setting it is on.This tells me the injectors are over fueling, Other than the pistons and injectors what is the differance between the 03 and o6 engine.

 

[Joseph Donnelly]

I covered the changes for 2004.5 when they came out; check the TDR back issues on this website from back then. I would not recommend mixing 2003-4 vs. 2004.5-2007 injector tips. A Smarty or TST PowerMax can give more timing advance to help mpg.

 

[cerberusiam]

Not sure on the Bully but maybe you need an update? I quit using it because it was an iffy programmer anyway. If you are getting 18 mpg with it stock or with the programmer there is not much wrong with the injectors.

The injector spray angle, piston bowl, and valve\valve seats are the major hardware differences. There are significant harness, programming, and electronics differneces on the platform.

 

[cum a long]

As i mentioned before the ecm and all the sensors are off the 2003 engine.So other than the dished pistons and 06 injectors engine should be the same as the 03.So by changing the injectors to 03 style it should preform like a ho high output 305.

 

[cerberusiam]

Wait a minute!! Your replaced the engine in your 03 with an 06 engine, or, replaced the 03 truck with an 06 truck?

Until this last post I was reading you replaced the truck with a newer one. If you replaced the engine then you have some tuning to do, that is why the Bully Dog is throwing so much smoke. You now have differnet nozzles and spray angle using a deifferent timing, pressure, and duration map. The typical reaction when doing what you did is more smoke from the engine.

 

[leaky gasket]

I've got a question too . What year truck and year motor do you have right now?
If you do have an 06 motor in your 03 truck and are using the 03 computer to run the 06 motor there may be more differences between the two motors that just injectors. I'm guessing you're going to have to take a look at the compression ratio and cams between the motors. To see if they're the same or different.(have to go,darn kids)

 

[cerberusiam]

I'm guessing you're going to have to take a look at the compression ratio and cams between the motors

There is not enough difference between years in thos eitems to matter. The timing, pressure, and duration is by far the biggest difference and has the biggest impact. The good news that can be tweaked to a point to help it run better. A UDC tune on it should be able to get it back in shape.

 

[cum a long]

Can you please explain what you mean by udc tune.; I hope I;m not coming across as a idiot I am a retired mechanic and before i put the 06 cummins in the truck i did some checking and was told i would have no problems with the switch if i 'd known i was going to have these problems i would have picked up a 03 engine.

 

[cerberusiam]

Physically, as you saw there are no problems. However, the electronics are another deal entirely. You can usually put an 03 engine into an 04.5+ with less problems than the other way.

UDC is User Defined Catcher, Smarty's custom programming tool. It allows to build some pressure, timing, and duration maps from scratch. Not as in-depth as EFI Live but has the ability to work on the non CAN systems. Its a computer job to build those profiles and load them, then, you have to test until you find a combo that works. Your wrenching with some electronic tools to ge tthings to work. You might ping AH64ID and see if he has some good ideas what it would take to build a UDC tune for that combo. The Bully Dog is not going to give enough control to really make it work well.

The 03 injector nozlles have 8 smaller holes and a longer duration and timing to put the fuel in the right spot. The 600 engines have a shallower spray angle with 5 larger holes to put the fuel in the right spot for a good burn. Whne you try to mix and match you get places in the rpm band where the fuel map is just not right. Add ot that the cam profile on the 06 engine is enough different it feeds the air differently and mizes more exhaust in to the charge.

The straight swap on a stock fueling map just gives more smoke when you don't tune them. They seem to run ok but just not exactly right.