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  1. #11

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    Ok I just went and looked and tugged at the wires. They all appear to be ok. I didn't notice any sterching and or cracking on them at the connector. They all stayed firmly seated in the connector.

    Aslo last night I took off my S&B Cone filter that I had installed becuase strangly it seems like everything I put the filter on the truck it ends up having some kind of issue but I never put two and two together untill last night. Would that have something to do with throwing the TPS out of whack and throwing the code (P0121)? I also cleared the code from my truck with my OBD2 tester and was just wondering how often the PCM cycles and checks for codes? I have forgotten the time periods?
    2007 SILVERADO 2500HD, CREW CAB
    353HP of american V8

  2. #12
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    121 code is when the PCM programing expects the TPS to be providing a pre determined angle/voltage and is not receiving the correct amount. you have to check the TPS/pcm connectors. PCM supplies the 5volts and receives the TPS signal. at idle tps =.6volts @WOT =4 volts.

    check the MAP for proper seating with the intake seal also connector. map voltage sent to PCM is used to predict the TPS signal. make sure air intake hoses have no leaks after the MAF.

    the cone air aftermarket setup could be confusing the PCM.

  3. #13

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    OK. I just went and checked the MAP sensor. I pushed down on it to make sure it was seated right and also unplugged it and plugged it back in to assure it was connected properly. So that should be ok now if it wasn't earlier. I Don't hear or feel any leaking air coming from the air intake hoses at all from MAF to the TB.

  4. #14

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    A air leak would throw a lean/ maf sensor code. The aftermarket intake wouldnt effect the tps alone. The tps is solid state sealed on the throttle body and nonserviceable. Get a wiring diagram, disconnect the battery and unplug the tb and the computer, find the proper pins and ohm out, if good hook up everything but tb and test for 5 volts and 12v for motor. See what readings you get.
    01' 1500 LT Z71 ECSB 5.3L
    line-x'd front brush guard with KC Daylighters, 6000k HID lows and highs, rewired highbeams, Trans-go mild shift kit, custom stainless duals, 3500 dually OEM taillights, K&N CAI. Still have OEM fender flairs and leveling kit in boxes waiting for time.


  5. #15
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    with aftermarket air intake hoses/pipes etc leaks between the MAF and throttle body are common. the air entering the engine and the air passing the MAF would create an error. depends on how much to throw off the PCM and the engine fuel management controls. a small leak could at some operating point create enough to create the code. then it should cause a low power mode..with the 121 tps error.

  6. #16

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    Well the light has not come back on since I cleared the code sunday night, It doesn't mean im out of the water yet becuase I had it stay off before for four days and then it would come back on. The one thing I have noticed is since I have put the stock air box back on and cleared the code the truck is more reponsive and its running smoother as well. Like i said before it seemed like everytime i put the cone filter on it would change the preformance of the truck negitivly but I never put 2 and 2 together.

  7. #17
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    with the OEM air box I feel this is better for use in the colder areas with snow/cold/road de ice chemicals. the box protects the filter from contamination. If it is in 100deg f plus temps a good add on.. need cooler air then.

  8. #18

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    Yeah you do have a point there, and we both know how horriable the road get here in the NE with the salt and the chemicals and how it just clings the the vehicles. When I removed the cone filter, I noticed my MAF was dirty so thats something else I want to take care of.

  9. #19
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    that MAF being dirty is a good indicator that this setup you had is creating filtration issues.

    I use the CRC maf cleaner on the small sensor wires. if these wires are dirty you will get hesitation on rpm increases at most all rpm/speeds. if you can see the dirt it was very dirty.

  10. #20

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    Yes its very dirty, I couldn't Believe it. Granted the truck has 116,000mile but still it shouldn't be that bad. The honeycomb is grey and the center stem in the MAF is almost black. I have to go grab some cleaner. I did have CRC cleaner but cant find it now that I need it. Im thinking about cleaning the TB as well.

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