power and mpg loss

[superdave]

i have a 1999 stock 3500 and it seems more and more to lose power and MPG... within the last 4 months everytime i pull a trailer I have to go out of OD where the same trailer on the same road before now was A-OK in OD... Also MPG has deteriorated from around 12. 8 loaded to 8. 2 loaded... No smoking, runs terrific empty. . When i accelerate I get a noise kinda sorta like a gas ping, (as described by the dodge technician today)... To me sounds more like when you take up slack in a bicycle chain when the bike wheel is off the ground... anyway,,,dealer checked engine out... no codes. transfer pump pressure 15 lbs,, boost pressure 7. 5 to 7. 8... everything "normal"..... I really love my dodge but am beginning to hate my Cummins..... there are no "recalls" according to dealer... I now have only 46000 miles on it... runs great empty but still great loss of MPG... but loaded even if doing only 60 MPH have to keep the pedal ALL the way to the floor... yet no smoking or missing or anything... ... H E L P... ... anything i can do or tell the dealer about..... the tech called a long time dodge cummins man at another dealer and described the "rattle/ping"... the older topline tech had never heard one do it he said..... so the tech told me to run it till something breaks so they can find it... . Should I trade it? Or put a "box" on it???? Thank you all so very much for your input.....

 

[fox]

Is your oil pressure still normal?? You may be describing a lower end problem with the noise.

The low power is probably in the pump, if it isn't delivering fuel it won't boost. Fuel filter? Where was the pressure checked? Probably at the pump in-put. ??

I'd ask the dealer to change the IAT sensor and MAP sensor.

Last , I'd try to find a friend who has an EZ box and try it to see if it changes anything.

Let us know .



fox

 

[GMcLean]

boost 7. 5 to7. 8??? should be more like 17-19 psi or more with no mod`s. . he should look a little deeper. either it is not getting any fuel, has a restricted exhaust, or there is something wrong in the turbo boost system.

 

[fox]

Yes, possibly the waste gate stuck open. I thought the numbers posted were odd, maybe a typo or miss understood statement from service miss-manager.



fox

 

[DavidD]

Dave, i would look for a leak in the pressure side of the iintake. from the turbo back examine all the fittings. I had a similar proble at about 15K mi. A lower rubber fitting was lose,looked good just sitting there but under pressure it leaked! You should see 21lbs of boost at full throtle undera load 3rd or 4th gear. You didnt mention what your mods are if any? Dave

 

[hammong]

I agree with the following few posts -- your loaded boost should be at LEAST 17 psi. If you're getting 7-8 psi, then you're drastically low, and that explains the power and mileage issues.



Have you changed your fuel filter recently? You quoted 15 psi transfer pump pressure -- that's good, but was it AFTER the fuel filter, or before the filter? If that pressure is pre-filter, you might have a clogged filter which would rob you of fuel when you need it.



Low boost with normal fuel delivery usually makes a lot of smoke. Restricted fuel delivery usually ends up in reduced/no smoke.





Possibly bad/going-bad injection pump?



Greg

 

[superdave]

sorry for the typo... . the boost pressure unloaded is 17. 6, not 7. 6... . sooorrryyy... ... ...