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ricelake922's avatar
ricelake922
Explorer
Aug 07, 2018

Is my turbo boost working properly

I have a 1996 Monaco Dynasty and thinking that the turbo boost is not working as it should. I will try to explain this the best I can. I drove from Ontario to New Jersey yesterday and had to endure the mountains along the way. By this I mean that when I would be driving and am going up a mountain, I am first going up with the transmission at 6 and as I am going up the transmission drops to a 5 and then as I am going up the transmission drops to a 4 with now reduced speed and the turbo boost has not yet kicked in. Then to push the RV up the mountain the transmission drops to a 3, reduced speed and turbo boost is now between 5 and 10 sometimes to a 15. The transmission as I am going up the mountain fluctuated between 3 and 4 and as I am going over the mountain with increased speed the transmission will go to a 5 and pick up speed. Can someone please explain how a turbo boost is suppose to be working properly as I believe mine is not. Thank you in advance.
Class A
  • doc_brown's avatar
    doc_brown
    Explorer
    Aug 07, 2018
    From my experience using Silverleaf my turbo boost would be at 20-22 if my transmission dropped from 6 to 4.
  • jplante4's avatar
    jplante4
    Explorer II
    Aug 07, 2018
    Yup, my CAT holds about 20 pounds of boost. You could have a stuck waste gate, a leak in a turbo line or a leak in the CAC.
  • ScottG's avatar
    ScottG
    Nomad
    Aug 07, 2018
    You need to get it checked out ASAP. If you have a plumbing leak then you could easily melt a piston.
    Personally, I would install a boost gauge.
  • Big_Katuna's avatar
    Big_Katuna
    Explorer II
    Aug 07, 2018
    If you have a laptop, you can buy Vmspc /Silverleaf and have real time diagnostics while driving.

    Boost, temps, error codes, etc.

    For abut the price Freightliner would charge to read codes.
  • jplante4's avatar
    jplante4
    Explorer II
    Aug 07, 2018
    ScottG wrote:
    You need to get it checked out ASAP. If you have a plumbing leak then you could easily melt a piston.
    Personally, I would install a boost gauge.


    Agree with Scott. We had a motor home in the shop last year that blew off a turbo tube and didn't get it checked. It melted the batteries.
  • tropical36's avatar
    tropical36
    Explorer
    Aug 07, 2018
    ricelake922 wrote:
    I have a 1996 Monaco Dynasty and thinking that the turbo boost is not working as it should. I will try to explain this the best I can. I drove from Ontario to New Jersey yesterday and had to endure the mountains along the way. By this I mean that when I would be driving and am going up a mountain, I am first going up with the transmission at 6 and as I am going up the transmission drops to a 5 and then as I am going up the transmission drops to a 4 with now reduced speed and the turbo boost has not yet kicked in. Then to push the RV up the mountain the transmission drops to a 3, reduced speed and turbo boost is now between 5 and 10 sometimes to a 15. The transmission as I am going up the mountain fluctuated between 3 and 4 and as I am going over the mountain with increased speed the transmission will go to a 5 and pick up speed. Can someone please explain how a turbo boost is suppose to be working properly as I believe mine is not. Thank you in advance.

    Turbo boost between 5 and 10 would be more like you'd expect on the flats. Hill climbing should be up closer to 20.
    Story short, it needs looked at!
  • ricelake922's avatar
    ricelake922
    Explorer
    Aug 07, 2018
    Thank you to all for your responses. I am going to take a different route home to avoid as much as I can the mountains. Can someone please explain what is a boost gauge as I have a turbo boost guage on my dash board. As I am in New York at a camp site driving home on Saturday it will make an appointment. Does the appointment need to be with Cummings?
  • Big_Katuna's avatar
    Big_Katuna
    Explorer II
    Aug 07, 2018
    Some responders didn’t get that you already have a boost guage.
    Any Freightliner or decent diesel shop should be able to read codes and diagnose your turbo function.

    You can also get full real time diags for all parameters with a Scanguage or Silverleaf system.

    I would get it looked at sooner than later.

    It’s Cummins, not Cummings.
  • jplante4's avatar
    jplante4
    Explorer II
    Aug 07, 2018
    Turbo boost gauge is what you need. As stated, with the throttle to the floor, you should be seeing 20 PSI of boost. Now, if your boost gauge reads in inches of manifold pressure 5-15 inches of boost above normal atmospheric pressure may be correct.

    Why don't you post a pic of the gauge?

    Another couple of resources for you are the Monaco Owners forum on iRV2 and the diesel RV club in FMCA

    Diesel RV Club

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