Forum Discussion

kiloo9's avatar
kiloo9
Explorer
Jun 25, 2014

Trouble with Workhorse 8.1 motor loosing power

Having trouble with an 8'1 workhorse gas engine. An acquaintance of mine is experiencing lost of power, engine will go to staled mode and gets "Reduce power" on the instrument panel. Now this has happen a couple of times once on the road while traveling at normal speed but other times it would happen when he pulls in for gas, once ready to take off will happen it would last probably about 5 minutes, after turning off the engine and waiting about 5 minutes then re start the engine it would be OK Normally by the time he would get some place for help the condition is gone. Recently He was able to have the coach in for service and the condition happen at the service shop, after some trouble shooting it was determine that the trotel valve and pig tail needed to be replace.the parts were replaced and in less that two day on a small trip it all happen again. Has anybody out there has ever happen to have this kind of problem or has some information that can help.
Class A
  • J-Rooster's avatar
    J-Rooster
    Explorer
    Jun 26, 2014
    I forgot to mention this before but sometimes you can solve your problem by disconnecting and reconnecting the throttle cable connection.
  • J-Rooster's avatar
    J-Rooster
    Explorer
    Jun 26, 2014
    allbrandauto wrote:
    when it says reduce power it means its going in a back up mode the problem is the throttle body is bad it doesn't have a throttle cable its electronic when they go bad it will go in back up mode very common
    X-2, happened to me same problem!
  • J-Rooster's avatar
    J-Rooster
    Explorer
    Jun 26, 2014
    This happened to me one time in Lake Havasu City, AZ. My 8.1 Vortec engine would run then lose power it turned out to be a electronic throttle module. It's located under the dash above your right knee. I had a Workhorse Certified Shop do the job since I was on the road and my bill was $50.00 including the part, labor and tax! Hope this helps you!
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jun 26, 2014
    First thing I'd check is fuel and air filters.

    After that... Hire a pro and throw money at him... Likely lots of it.
  • mnoeltne's avatar
    mnoeltne
    Explorer
    Jun 26, 2014
    Since it is getting the "reduced power" message on the panel, it sounds like the computer is sensing a problem and going into "limp home" mode where it uses a preset map that lets the motor operate, but not at full power or efficiency.

    That could be the sign of an actual problem, or since you say it goes away, it is more likely a sensor overheating, and then it starts working again after cooling off. I'm not familiar enough with the 8.1 to know which sensors tend to do this on that motor, even though I have an 8.1 in my rig.

    On other vehicles it's quite often caused by a crankshaft position sensor or a camshaft sensor going bad. Some will throw a CEL code, some don't.

    They really need to find someone familiar with GM V-8's, especially the 8.1, and see if they can shed some light on which one is likely to go bad.
  • Deano56's avatar
    Deano56
    Explorer
    Jun 26, 2014
    allbrandauto wrote:
    when it says reduce power it means its going in a back up mode the problem is the throttle body is bad it doesn't have a throttle cable its electronic when they go bad it will go in back up mode very common
    yes, we just had a gmc truck do the same thing and that was the fix. Buy the way guys, he said it would loose power, not shut off.
  • frankdamp's avatar
    frankdamp
    Explorer
    Jun 26, 2014
    When you turn the power "loose" does it go galloping off into the sunset? Maybe the rig is "LOSING" power, which is a different ball-game altogether.
  • allbrandauto's avatar
    allbrandauto
    Explorer
    Jun 25, 2014
    when it says reduce power it means its going in a back up mode the problem is the throttle body is bad it doesn't have a throttle cable its electronic when they go bad it will go in back up mode very common
  • Doug_E_'s avatar
    Doug_E_
    Explorer
    Jun 25, 2014
    What year is this 8.1? On the older 8.1s there was a problem with the crankshaft sensor getting hot and warping, when this happened the vehicle would shut off. After the sensor cooled down the engine would re-fire and run normal again.
  • wilanddij's avatar
    wilanddij
    Explorer
    Jun 25, 2014
    Check the chassis battery cable connections. If they are loose or corroded badly the engine will go into limp mode.

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