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Re-Idle woes....

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by det45, Aug 30, 2000.

  1. det45

    det45 1/2 ton status

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    Well I got the new (Throttle Position Sensor) installed and my 89 TBI K5. My idle problem seems to be fixed. Prior to replacing the TPS, my K5 would not idle up when first started, it would stay at a low idle even if it was a cold start thus creating stalls until the engine warms up. At first I thought it was the o2 sensor so I replaced it but it didn't fix the problem. I checked the ECM for trouble codes and got a code 21 (Bad TPS) Thats why I R&R the TPS. The sensor cost me $23.00 at Advance Auto (Texas). So far everything is working for now but I will really be able to tell when I drive it tomorrow to work. Oh one more thing, how do I clear the trouble codes from the ECM?
     
  2. fr8train

    fr8train 1/2 ton status

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    You have to disconnect the neg. batt. cable for a few sec. How long did it take you to put the sensor in? Did you calibrate it? I got and OEM one from Napa and it came with a big instruction sheet. I just took it and the sheet to a shop and let them muck with it.
     
  3. det45

    det45 1/2 ton status

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    I just R&R the sensor. I didn't do any adjustments. Hopefully I'll get lucky. The instructions said that I had to take the TBI unit off of the truck so I said forget that and just replaced the sensor. I did disconnect the neg cable on the battery however I still get the 21 code after reconnecting the cable. Even though my truck is idling normal again, I still may have to adjust the sensor. I'll let you know what happens tomorrow..........Det45
     
  4. fr8train

    fr8train 1/2 ton status

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    Cool, keeping my fingers crossed. The manual stated when you remove the cables it removes the presnet memory from the ECM. Its not the first time manuals have gone wrong. Hope it works man.
     
  5. Casey 86K5

    Casey 86K5 1/2 ton status

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    You can also pull the fuse for the ECM to clear the codes, then you wont have to go and reset your clock and all of your radio presets.
     
  6. realsquash

    realsquash 1/2 ton status

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    Read this carefully and you shall fix your still-existing problem. You did in fact reset the code in your computer, only to have it reappear. Your problem is there there! A code 21 on your engine means that the TPS voltage is high (above 2.5 volts) for 8 seconds, while vacuum is under 51kPa. In other words, loosen your new tps, rotate it counterclockwise until it stops, and tighen your screws (this is the low limit). Unhook neg batt cable for 10 seconds or so and start the engine w/o pushing the gas a single bit. Your code 21 should go away. If you get another code now, it could be a 22, which is TPS low (under .20 volts). If you do get this code 22, don't fret, just nudge the TPS a little clockwise, disconnect batt cable, and start it up. Repeat until you get no error. Or you can do it right the first time and use a digital voltmeter to measure the TPS voltage, but I can't remember the wire colors right now. The only other thing that could be happening is a burnt/shorted TPS wire, or a bad ECM (very, very unlikely).

    If you need more help than this, post something else.

    Squash
    http://www.trailrunners4x4.org/users/realsquash
     

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