Stumped on 97 GMC Jimmy problem

Discussion in 'General Chevy & GM Tech Questions' started by exceler8, Sep 30, 2009.

  1. exceler8

    exceler8 Member

    I have a 1997 GMC jimmy. I cant seem to find the what is causing my problem. He is the problem. I dove it for months without any issues. Then out of nowhere, it started acting up. When you get in and drive for 10 to 20 miles, all is good. Then if you have to stop or have to take a hill or anything to give it gas, it bucks and goes slower. it seem the less load you put on it the faster it will go. Any load will slow it down. You then have to pull over and shut it off. When you start it you can then drive another 10 to 20 miles or until you have to slow down or stop. Then you have to shut it off again for 10 seconds or so. The only code I have is a 440 and a 131. Now I had these codes all summer to without any issues. It seems that it mite be temp related. I know Some are going to say simple things. Been there done that. Did the fuel pump, fuel filter, 2 new O2 sensors, tune up, dry gas, new gas cap. See if you can shed some lighy on this for me. I would greatly appreciate it.:neutral:
  2. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    You seem to be oblivious to the problem at hand. Whenever a GM Powertrain is not performing correctly the PCM usually sees the problem and sets a trouble code. In your case it set 2 codes which you have elected to ignore. First step is to determine which code is the primary code and go after it first. Many times a problem will set multiple codes and fixing the primary code will fix the secondary codes as well. In this case it looks to me like the EVAP problem is causing a very rich condition which is setting the O2 code. Just a SWAG but I'll bet the canister is flooding and causing the engine to run very rich during a purge cycle. This theory would be easy to prove or disprove by taking a look at the short and long term fuel trims.

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