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Thread: Reduce Engine Power.. NEED HELP!!!

  1. #1
    Join Date
    Sep 2007
    Location
    Monroe,Louisiana
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    194

    Reduce Engine Power.. NEED HELP!!!

    I finished putting my tranny in this morning. Started the truck and it says Reduced Engine Power. I can floor the gas and nothing happens. I scanned the computer and it has a TPS error. It will idle very rough but the gas pedal doesnt work. Do i need to change the Throttle body, the Trottle position sensor, or what? Maybe i didnt plug something back in? Triple checked my connections. I really need some help. I cant find anyone that knows what to do, the dealer couldnt even tell me how to fix it.
    2003 RCSS Chevy 5.3L Fully Bolted, Cammed, Yanked, and 342s. Borla Exhaust w/ Electric Cutouts.

  2. #2
    ff_jeff Guest
    sounds like you have either an unpluged sensor/s, or you have a hole in the intake manifold.

  3. #3
    Join Date
    Aug 2005
    Location
    St. Anthony, Indiana
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    1,592
    check to make sure you didn't pinch any wires between the trans and engine. also make sure you have all the grounds an back of the engine attached.

  4. #4
    Join Date
    Jul 2008
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    329
    Check the connectors to your throttle body very carefully. The reduced engine power error is usually caused there.

  5. #5
    Join Date
    Jan 2008
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    1,550
    Quote Originally Posted by Madd Maxx View Post
    Check the connectors to your throttle body very carefully. The reduced engine power error is usually caused there.
    X2 i had the same problem and had to replace my tb/tps. make sure the plug is all the way in

    04 RCSB 5.3, Homemade 80mm FM, TU1, TH400

  6. #6
    Join Date
    Aug 2008
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    It's not a part and it's not the intake. The TACM is not on the data bus but will tell on itself to the PCM. TPS codes on a DBW system are almost always caused by one of the following listed in order of commonality

    1) Wires broken inside the insulation to the throttle body. Take all the the convoluted crap off the harness and pull test each wire one at a time at the throttle body. If one of them has a problem it will stretch a lot more than the others and the insulation will turn white at the break.

    2) Weak battery. When the battery is only weak or the vehicle has to be jump started (long time sitting, left the headlights on, etc.) the TACM and the PCM wake up at different times tripping an error since one cannot find the other.

    3) Rodent damage or loose fastening of the PCM ground (black with white stripe) wire at the back of the block passenger side coming from the big engine harness.

  7. #7
    ff_jeff Guest
    The only time I have ever seen reduced engine power was when the thing caught on fire. I could not even read the mileage.

  8. #8
    Join Date
    Aug 2008
    Location
    North Texas
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    Any news?

  9. #9
    Join Date
    Sep 2007
    Location
    Monroe,Louisiana
    Posts
    194
    Well, Yesterday i cleaned all the connections and replaced the battery. I started up fine. Took it for a test drive. The speedo goes crazy. Its jumping all over the place. The tranny shifts fine in 1st and 2nd but 3rd &4th it downshifts and just revs up! I ddont know what the deal is i have a new speen sensor in it. Any ideas?
    2003 RCSS Chevy 5.3L Fully Bolted, Cammed, Yanked, and 342s. Borla Exhaust w/ Electric Cutouts.

  10. #10
    Join Date
    Aug 2008
    Location
    North Texas
    Posts
    12,078
    The trans issue sounds like smoked 3-4 clutches. Might have a trans guy look at it.

    03-04 are notorious for speedo problems but usually it's just inoperable or sticking, not jumping. Wiring issues at the VSS connector are common. Check both the green and the purple wires for stands broken inside the insulation. Also, if it's 4WD there is another connector just a foot or so from where it plugs into the VSS...it's a jumper to accommodate the 4WD wiring harness. Check for damage there as well.

    Did you pull test all the wires individually at the throttle body as suggested my Madd Maxx and I? Did you check the black and white ground for PCM?

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