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  1. #1

    Default Reduced Engine Power Problem

    I've had this problem happen a 3 or 4 times now and have no idea what is causing it. Hopefully someone can help me.

    I have a diablo programmer that I use with my truck (2004 Silverado 2500 w/6.0L). I use the diablo tune and have been running 93 octane through it like I'm supposed to with the performance tune. But within the last month or so, I have had a problem when I go WOT. All of a sudden the engine dies!! It will just go down to almost no RPMs and has no acceleration. Each time this has happened the check engine light comes on as well. So I pull over to the side of the road or in a parking lot, park it, and then turn it off.

    After I wait 20 or 30 seconds, I turn it back on and the check engine light will remain on, but the RPMs are running fine and the engine has it's power back. And when I drive it it's fine after that. I then restore the factory tune settings with the handheld and that takes off the check engine light. Then I reinstall the performance tune and it's fine until it happens again.

    Out of the few times it's happened, 2 of the times one the dash it actually displayed "REDUCED ENGINE POWER."

    If anyone has any idea of what I can do to stop this from happening that would be great! And please just help me with this problem. I'm not looking for people to simply tell me "Get a custom tune!" or "Shoulda gone with SCT!" or anything like that. If you have some good helpful knowledge about this problem, then please share!

    2004 Silverado 2500 "Judas"
    Crew Cab and Short Bed
    6.0L Vortec
    Diablo Predator
    True Dual Exhaust: Hooker MaxFlow Mufflers and X-Pipe
    Drop-In K&N Air Filter
    Alpine Stereo System: iDA-x303 Deck, SPS-600 Front and Rear Speakers, KTP-445 Amplifier

    Future Upgrades Include:
    Cosmetic/Other: Spray-In Bed Liner, HID head lights, Leveling Kit
    Performance: Underdrive Pulleys

  2. #2


    did you have the codes read. it is going into the safe mode for one reason or another. is it at a certain rpm where it shuts down (ie it may be revving higher than the computer believes safe so it goes into safe mode) if thats the case does the diablo have the ability to adjust the rev limiter?
    2004 Silverado 2500 Crew Cab 4x4, AMSOIL EA air filter, Granatelli MAF sensor, Throttle body spacer, Magnaflow exhaust (true dual to 2 in 1 out muffler), 6" ProComp lift (add a leaf and 5" superlift rear block), Bilstein shocks, 35's (Cooper Disoverer ST) and 4.10 gears, Rhino Liner, EGRUSA fender Flares and widow visors, extended stainless steel brake lines, firestone airbags w/onboard air compressor, Pioneer Avic X940BT navigation, Accel backup camera.
    1960 Land Rover Series II 88
    2001 Pontiac Sunfire
    2013 Toyota Avalon Limited (Wife's Car)
    NRA Life Member

  3. #3


    The diablo does allow you to change the rev limiter. I haven't toyed with that part yet though.

    As far as the codes, I have not had a chance to read them. When the check engine light comes back on again, if it does it again, then I can read them.

    I'm not so sure that it has any thing to do with the amount of RPMs though. It won't do it anywhere in the throttle range except for WOT. The diablo does have the ability to allow you to change different settings at various throttle percentages. But I'm not really sure what I should be adjusting.

    The safe mode that you are talking about though, what are typically the reasons that these engines will engage that?

  4. #4


    Quote Originally Posted by c_m_chance View Post
    The safe mode that you are talking about though, what are typically the reasons that these engines will engage that?

    Usually things like revving too high, tranny temp too high, engine temp too high. Probably alot of other things too. basically any parameter that the computer sees as being too far outta whack that will cause damage to the powertrain. Hopefully a tech (on the site) can give some better info on that.

  5. #5


    Ok. So you think this problem could be fixed by adjusting some of the parameters on the tune that I upload to the computer? I'm not to sure on things that would be safe to change as far as the revving and all that, but I'm sure I could figure it out.

  6. #6


    after installing the diablo tune on my truck it says the same thing, wats up with that?

    2006 silverado z71
    295-70-R17 nitto trail grapplers
    flowmaster 40 series dumped
    2'' rough country leveling kit
    k&n CAI
    throttle body spacer
    15'' kicker cvr & 2 10'' kicker cvr /w 1800 watt kenwood amp
    7'' jvc kw avx810 double din
    diablosport predator

  7. #7
    Sr. Engineer
    Join Date
    Jun 2009
    San Diego, CA


    If you are running into this problem more than once, I would suggest contacting Diablo, and not running the tune until it is sorted out.

    I would definitely get the codes read, as I am sure Diablo would want to know what it is as well. The Reduced Power is merely letting you know that it is a problem related to the electronic throttle control and is thus snapping it shut.
    Black Bear Performance- Custom Tuning Solutions

    Authorized EFILive and MAGNACHARGER seller

  8. #8


    well every time i install the 93 octane tune it says that after im done, but no lights ever come on exepct knock sensor low input or out put, something like that. so is that engine power reduced thing not usual?

  9. #9
    Sr. Engineer
    Join Date
    Jun 2009
    San Diego, CA


    Definitely not normal, and I would not run it like that.

  10. #10


    as far as the message reduced engine power my hypertech diplays that and so does my friend bully dog power pup
    :great:FUTURE Mega Millions Winner:great:

    2007 Polaris 800 X2
    1997 Pontiac Sunfire
    2006 Pontiac Grand Prix
    2008 Chevrolet Uplander
    2004 Chevrolet 2500 HD 4x4 6.0

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