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Hesitation Problem

Discussion in 'General Chevy & GM Tech Questions' started by willbradfan, Aug 18, 2010.

  1. willbradfan

    willbradfan Rockstar 100 Posts

    Just today I started noticing my 96 suburban really starting to hesitate. I noticed it when I came to a complete stop at a light and then hit the gas casually and it will just hesitate and then go. I also noticed when I was going about 50-60 on the highway and im in OD with the rpms between 1000-2000 that i will get a pretty consistent hesitation. I got home and messed around with it by doing several stop and goes with WOT and you could just feel it hesitating even more. I stopped and filled up with a higher octane gas since ive been putting just regular 85 in my suburban since that is my regular octane at my elevation (6000ft). When I got home i ran down to oreillys and got 2 bottles of seafoam. I put a bottle and a half in my tank since I had a full tank and a 1/3 of it in my vacuum line. Still hesitates after putting it through the vacuum line, guess i just need to wait for the fuel tank of seafoam to kick in or else maybe its something else...
    Im going to take it to the dealer on friday or saturday if i can't figure it out. The guy at the dealer usually tells me if i can fix it once they find the problem. (friend of mine)

    Any help is greatly appreciated, thanks!

    I also cleaned my K&N filter/MAF/throttle body this past weekend as well, if that would have anything to do with it?
  2. MightyMax

    MightyMax Rockstar 100 Posts

    Coolant Temp Sensor or TPS??
  3. willbradfan

    willbradfan Rockstar 100 Posts

    the coolant temp sensor was replaced a couple months ago when I had a new radiator put in. From what I recall, the throttle position sensor is still the original sensor.
  4. MightyMax

    MightyMax Rockstar 100 Posts

    With a MultiMeter you can test the TPS pretty quickly and easily.

    Maybe try that.
  5. willbradfan

    willbradfan Rockstar 100 Posts

    Do you know what readings I should get if its good/bad?
  6. MightyMax

    MightyMax Rockstar 100 Posts

    There are 3 wires.

    2 of which you can test for voltage w/ the connector out (this is the side going to ECM/ECU)
    Should be around 5V.

    If you plug it back into the TPS Sensor, the thrid wire (Probably Blue in color) you will need to test for voltage. You will need to get a probe you can stick down into it that will allow for you to test.

    Connect positive lead to backprobe, and negative lead to a ground.
    With key to "ON", engine off.....you should read under 1V (maybe ~0.5)
    As you open the throttle up (lower resistance) your voltage should increase (to maybe ~4.5 at wide open)......

    Check out this video.
  7. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    Have you checked for a vaccume leak?
  8. willbradfan

    willbradfan Rockstar 100 Posts

    No I haven't, whats the easiest way to determine if you have a vacuum leak?
  9. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    A few years back I took my '96 Suburban to a shop and had them do a SMOKE test. They pump smoke into the engine and the smoke comes out any vaccuum hose with a crack in it. I had 3 small leaks and that was the rough idle problem.
  10. willbradfan

    willbradfan Rockstar 100 Posts

    I do have a rough idle that i have never been able to find the cause of, the idle goes back to normal once it is out of the Parking gear though. I will test my throttle position sensor when I get home from work.

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