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  #1  
Old 04-14-2007, 02:33 AM
 
Join Date: Apr 2007
Posts: 11
disturbedgame is an unknown quantity at this point
Default Throttle position sensor is haunting me!

95,blazer, 4x4, 4.3 (w engine code). Check engine came on 10 minutes after i bought it, and stayed on since then(4 months ago). aside from gas mileage being around 14 mpg, It was fine for a while. Started to idle rough periodically, but was always fine when on the gas. Then it started dying out on me when cold. once it warmed up it was usually ok. So i hadAdvance Auto Partspull the check engine code, and it was 1406, and 0122. i bought a new throttle position sensor, cleared the pcm, and started it up. Fine for 30 seconds, then wouldn't run. Figured out the TPS was the incorrect part. Proceeded to get a TPS from Auto Zone. That one didn't work either. Had to get one from a different store, and now the truck will not run! It will start, but almost immediately die. After trying to start it about 20 times, I got it running(holding pedal down half way or so). It absolutely will not idle on it's own anymore. Cleaned EGR and the upper intake cleaned(very carbonized on the driver-side). Cannot figure it out for the life of me. oh yeah, the only code showing up now is 0122, which is throttle position sensor. i'm on my 4th throttle position sensor, is it possible autozone, advance auto, and my local mom and pop parts store all have different TPS's and I still dont' have the right one, or is there something else i'm missing. Anyone with info, or help?????
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All I want for christmas is a smooth running truck
  #2  
Old 04-14-2007, 05:13 PM
 
Join Date: Dec 2006
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Posts: 85
filstoy is an unknown quantity at this point
Default RE: Throttle position sensor is haunting me!

Doesn't nessecarily mean it's in the sensor itself. It could be elsewhere in the circuit. You can test the sensor with a volt meter. If you have your original sensor (part # should be stamped on it), you can go to NAPA's site and cross reference the part number. They are usually acurate so you should be able to figure out if you got the right one or not. Also DTC P1406 is EGR position sensor (which it looks like you already knew). Here's the diagnostic table for your car. For some reason when I paste it, it looks OK but when I view the message the table gets screwed up. If someone can tell me what I'm doing wrong, I'll repost it. Here it is anyway so hopefully you can pick out something here that will help you. The way it's supposed to look is each step is numbed and then the next column gives the value (voltage) and then yes and no columns. If you read it closely you can probably see what I mean. The table starts where it says
Step Action Value(s) Yes No


DTC P0122 Throttle Position (TP) Sensor Circuit Low Voltage Circuit Description The Throttle Position (TP) sensor provides a voltage signal which changes relative to the throttle blade angle. The TP sensor signal voltage varies from about 0.5volts at idle to about 4.5volts at Wide Open Throttle (WOT). The TP sensor signal is one of the most important inputs used by the VCM for controlling the fuel and for most of the VCM control outputs. Each time the voltage drops below 1.25volts and stops, the VCM assumes this value as 0 throttle angle. The measures the percent throttle from this point on. The DTC is a type A DTC. Conditions for Setting the DTC The following conditions will set the DTC:[*]Engine running[*]TP sensor voltage is less than 0.15volts Action Taken When the DTC Sets Important The scan tool will not indicate a default value. The VCM sets the DTCP0122. The VCM turns ON the MIL when DTCP0122 is reported, and 1 failure has occurred. Conditions for Clearing the MIL/DTC The VCM turns OFF the MIL after 3consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40warm-up cycles (the coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle) or the scan tool clearing feature has been used. Diagnostic Aids The scan tool reads the throttle position in volts. The TP should read about 0.45 to 0.85volts with the throttle closed and the ignition ON or at idle. The voltage should increase at a steady rate as the throttle is moved toward Wide Open Throttle (WOT). An open or short to ground in the 5 volt reference circuit or the TP sensor signal circuit results in a DTC P0122. Refer to Intermittent Conditions . Scan the TP sensor signal while depressing the accelerator pedal with the engine stopped and the ignition ON. The display should vary from below 1.25volts (1250mV) when the throttle is closed, to over 4.5volts (4500mV) when the throttle is held at the Wide Open Throttle (WOT) position. Test Description The numbers below refer to the step numbers on the diagnostic table. [ol]If the TP signal measures less than 0.15volt, then the fault exists. This test simulates the DTC P0123 (high voltage). If the VCM recognizes the high signal voltage, the VCM and the wiring are okay. This test simulates a high signal voltage in order to check for an open in the TP signal circuit. This step checks the 5 volt reference circuit for an open, short to ground, or a poor connection, or a faulty VCM. The VCM terminals GR12 and GR27 are spliced together inside the VCM. When checking the 5 volt reference for a short to ground, both the 5 volt reference circuits and all the components on the 5 volt reference circuits must also be checked.[/ol] St
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1999 Blazer 4X4
4.3 Automatic
  #3  
Old 04-14-2007, 06:04 PM
 
Join Date: Apr 2007
Posts: 11
disturbedgame is an unknown quantity at this point
Default RE: Throttle position sensor is haunting me!

ok, so assuming i DO have the right throttle position sensor....i replaced the fuel pressure regulator today, with new return lines, the whole deal aside from the spider assembly. no leaks, everything there seems fine. New fuel filter, PCV valve, and a screened EGR gasket after cleaning all the carbon out(definitely dirty in there, but no chunks like other people describe). the EGR valve is moving pretty freely(not sure how to test if it's in working order, but it moves freely now). i appreciate the diagnostic table, but from what i understood of it, i need to test with the vehicle running, and that's not gonna happen. after putting the upper intake back together with the new pressure regulator in, fuel filter, and pcv valve, the truck was very hard to get started. finally got it started, it put putteda few times, and died. Now it starts almost immediately up, but dies within 5 seconds. regardless of whether i'm on the gas or not, it doesn't make a difference. same thing every time like clock work. I'm really lost on this one.
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All I want for christmas is a smooth running truck
  #4  
Old 04-14-2007, 07:29 PM
 
Join Date: Dec 2006
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filstoy is an unknown quantity at this point
Default RE: Throttle position sensor is haunting me!

TPS can be checked with ignition in on position. Engine doesn't have to be running. Here's a link that explains how to test it in case the other info is too confusing.
http://www.autozone.com/az/cds/en_us...rInfoPages.htm

BTW, make sure you have the 5 volt reference voltage to the EGR since you disconnected it and it sounds like it could be an EGR problem to me. Make sure you didn't blow the fuse.
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1999 Blazer 4X4
4.3 Automatic
  #5  
Old 04-14-2007, 07:45 PM
 
Join Date: Dec 2006
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Posts: 85
filstoy is an unknown quantity at this point
Default RE: Throttle position sensor is haunting me!

Just thought I should add that I don't mean to put the cart before the horse. P0122 is circuit low voltage so do the voltage test on the TPS to make sure you've got the 5 volt reference and the proper open and closed throttle voltage before I go confusing you with the EGR. Wish I could figure out how to post these tables correctly because I've probably got the ones you need. Were you able to verify that the TPS you bought is the correct one ?
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1999 Blazer 4X4
4.3 Automatic
  #6  
Old 04-14-2007, 09:16 PM
 
Join Date: Apr 2007
Posts: 11
disturbedgame is an unknown quantity at this point
Default RE: Throttle position sensor is haunting me!

as far as i can tell, this one lines up with the original and the oe number cross referenced to it at the parts store, so i believe i have the right TPS, finally. I'm headed to the garage right now to check the EGR fuse and then i gotta run and borrow a voltmeter so i can see if i can get a voltage reading on the TPS. I'll check back in a while with an update. Thanks for the advice, I feel like I'm getting somewhere. Oh, by the way, i hooked up the fuel pressure tester, and it seems to hold a steady 60 psi throughout, even when it dies 3seconds after it starts, it holds at 60. I wasthinking it could've been an intermittent fuel pump, but not so much anymore.
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All I want for christmas is a smooth running truck
  #7  
Old 04-14-2007, 09:48 PM
 
Join Date: Apr 2007
Posts: 11
disturbedgame is an unknown quantity at this point
Default RE: Throttle position sensor is haunting me!

using my haynes manual, i'm not the greatest at reading wiring diagrams, but the egr operates under the ENG-1 fuse, i'm assuming, and no it was not blown. there is no relay for the EGR is there? and does anyone know if there is a way to test my EGR itself? if it's not a fuse, or carbon build-up, it could be the EGR itself, but i'd like to test it before i buy a new one, they're a little pricey.
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All I want for christmas is a smooth running truck
  #8  
Old 04-14-2007, 10:00 PM
 
Join Date: Apr 2007
Posts: 11
disturbedgame is an unknown quantity at this point
Default RE: Throttle position sensor is haunting me!

the unfortunate news is......not sure why, but when i start it now, it runs for about 15 seconds, then just dies, same thing every time i start it. at 15 second intervals, it might take me a while to get it to the nearest cliff! i'm very puzzled andi still refuse to take it to a dealer. i'm only 75 bucks into it as of now, and my patience isn't completely gone yet. keep the ideas coming, guys.
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All I want for christmas is a smooth running truck
  #9  
Old 04-14-2007, 11:20 PM
 
Join Date: Dec 2006
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Posts: 85
filstoy is an unknown quantity at this point
Default RE: Throttle position sensor is haunting me!

Don't buy an EGR yet. Too expensive to guess. I sent you an e-mail and the Mods are trying to help me figure out how to post the info.
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1999 Blazer 4X4
4.3 Automatic
  #10  
Old 04-15-2007, 11:02 PM
 
Join Date: Apr 2007
Posts: 11
disturbedgame is an unknown quantity at this point
Default RE: Throttle position sensor is haunting me!

still having problems. it now runs, but runs so rough it almost dies every other second, and sometimes does die. can't figure it out for the life of me. please, anyone have fresh ideas?
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All I want for christmas is a smooth running truck
Old 04-15-2007, 11:02 PM
 
 
 
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1995, 1999, 2, 43, 97, 99, blazer, blazerforum, chevy, location, poppet, position, senor, sensor, throttle


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