reduced engine power

Discussion in 'GM Powertrain' started by millerahf, Jun 1, 2009.

  1. millerahf

    millerahf New Member

    wondering if anyone can give advice.

    Bought 2005 suburban with 38K miles on it about 6 months ago.

    After 2 months check engine light and reduced engine power went on.

    Took it to the local dealer in Norfolk Va.
    Codes showed throttle body issue and part replaced.
    2 weeks later same issue, took back in and had the "wiring" replaced per senior GM tech advisor.

    Ran fine until over the weekend when I was towing my boat across the cheasepeake bay bridge with the ac on and it powered down to max of 10mph in the first tunnel....lots of fun...Turned engine off and restarted it and it ran ok for about 30minutes with ac on and same thing. May be coincidental but once i turned the ac was turned off it did not happen again, but i was turned around by that point and was close to home. CK engine light off and reduced engine power off this am.

    Fuel to the flame......Turns out when the truck was under warranty from prior owner and the throttle had already been replaced about 10K before i bought it....although i did not see record of this on car fax!

    Any rec's on what the real problem may be?
    Last edited: Jun 1, 2009
  2. heavy chevy

    heavy chevy Epic Member 5+ Years 500 Posts ROTM Winner

    The catylitic converter may be stopped up. Or you could have a vacume line on wrong or off.
  3. Crakums_GT

    Crakums_GT Epic Member 5+ Years 500 Posts

    I'm thinking it may be a MAF problem. I've heard of power issues due to a problem with the mass airflow sensor. That may have caused the code for throttle body issue. I still consider myself a novice on EFI engines though so it's just a thought. I'm probably way off but it may be something to look into. Are there any other symptoms that you notice? Noises, smells, etc...?

  4. millerahf

    millerahf New Member

    thanks for the insight....spoke to dealer yesterday and they said "more wiring needs to be replaced"....which sounds to me like they are not sure what is really going on with the response to the early suggestions....there has been no abnormal noises or smells and the truck runs fine btwn these recurring episodes.....i appreciate the suggestions.....better ideas then the "pro's" have offered.
  5. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    A throttle body will not cause intermittent problems like that. You have an electrical problem. What code set the second time it screwed up?
  6. millerahf

    millerahf New Member

    will check the codes when i pick it up and let the group now...again thanks.
  7. Brad Davison

    Brad Davison New Member

    I have a similar problem with my 2005 Suburban 2500 LT. I too have been dealing with this problem for over a year. I initially got OBII codes of P2135 and P1516. After going through all of the recommendation that I have found on the internet forums and etc, I have been unsuccessful in correcting the issue. Early on I replaced the Throttle Position sensor on the accelerator itself, then the throttle body as well as the throttle position sensor (TPS) on the throttle body and the electrical harness to the TPS. When none of those worked, I next went through and cleaned all of the connections and grounds including those on the control module next to the washer fluid reservoir at front of the drivers side fender. That changed my codes from those mentioned above to P1125 and P2120. I am not really sure where to go from here. The only thing that I am very certain about is that the problem is electrical in nature and probably due to a bad ground but I have not been able to locate and so also have not been able to fix the problem. I am looking for ideas and feed back. I have included a few pictures of the possible problem areas. I think that I got them cleaned up properly but still have the same problem.

    Attached Files:

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