2006 Mega cab not running right--advice please

[fox]

This is my friends truck.

Truck is all stock except for lift pump. I don't remember if it is Air Dog or Fass.

It idles with a skip occasionally, and the best mileage is around 15-16 on highway with nothing in tow.

It cranks quite a bit longer to start than another 03, especially cold.



No codes, so where do we go? What to look at.



I wish injectors were not so expensive, we could try another set, but that is quite a bit of money to spend guessing!



Thanks for the help.

 

[cerberusiam]

Injector return flow test to see if they are bypassing too much fuel causing hard start and low rail pressure.



A cylinder contribution reading to see if ones is adding more fuel than needed.



Those 2 should give a pretty good idea if it is an injector problem. You can get the block off tool and start capping each injector to see if its one or 2 causing the hard start problems and return flow.



Aside from that its replace them all and see if cures it.

 

[fox]

How about a link to the test? Is it a dealer or Cummins test?



Do you agree that he should be getting better mileage?

 

[cerberusiam]

Search on here for the injector test. I think Bob4x4 or Sag2 posted the specifics. If I find it I will post it.



Yeah, it sounds like a bad injector(s) and yes the mileage should be a little better, IMO. There are a lot of variables that contribute to the final number os its hard to tell exactly what it should be. What he has is not bad as the mega's just seem to be off a bit in the mpg.

 

[CDonaldson]

When my 2006 truck was new I got the 15-16 mpg's. Once broke in they went up. Running empty a lot, the mileage will go down, i have experienced that. Seems like it needs to be put to a load every so often to get the mileage up. When I see my mileage dropping, I hook about 18K and take it for a ride, then the mileage comes right back up.



Do the rec injector tests ^^^ and see what you have, if all are good, try a good heavy tow and then see what you get. Also, fuel pressure or over fuel pressure can cause the symptoms you are having, or a bad pump getting ready to go. There are discussions here about an occasional intermittent stumble due to the pump. Long crank can be associated with the injector tubes not being torqued properly, and some of those who re-torqued did solve the problem of both the stumble and some also reported their fuel mileage went up.







CD

 

[JExum]

15-16 mileage on the highway is not bad too if your speed is above 65mph. With my smarty thats about what I average on mine also. 500hp motors just can't get the mpgs the 1st gens did but we have plenty of power to spare.