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Car will not start.....need help, reads P0121

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Old 07-23-2009, 05:02 AM
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Default Car will not start.....need help, reads P0121

I left my car alone for one week because i was on vacation. I came back, battery was drained and after i got a new battery the car cranks but won't start. Codes that ran include: P0103, P0121, P0123. I just replaced my MAF meter and now only code P0121 (P0121 Throttle Position Sensor/Switch A Circuit Range/Performance Problem) is shown.
Engine still crank... just won't fire, I checked the spark plugs and realized that they are not giving any spark when i try to start the car. I don't want to buy a new TB unless i really have to...anyone have any ideas? BTW i am running the turbonetics kit.
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Old 08-06-2009, 09:32 PM
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just changed the TB and the pedal position sensor. no changes...
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Old 08-07-2009, 03:15 AM
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what engine management you running?
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Old 08-07-2009, 03:33 AM
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Man this gotta suck, good luck in fixing your problem.
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Old 08-07-2009, 03:51 AM
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Yea please provide as much info as possible to help us diagnose the issue. Was anything changed since car ran other than batt going dead? Have you checked voltage at battery during crank? Could be an elec issue. Also things wed need to know - transmission, mods (incl turbo, boost, motor work, etc), engine management, and anything else you can think of. Also were you previousely having ANY issues with the car?
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Old 08-10-2009, 05:32 PM
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I am having the same exact problem with mine right now man...no ignition spark. Mine was reading off that all the coils where bad..... which i know cant be. But i just recently about a week ago rebuilt the motor. I have the AEM standalone and for some reason my STAT SYNC is not coming on when trying to start the car. SO... there for what people were telling me is to check the sensors....Cam position sensor and crank sensor. But since it did not throw that code then i am not sure.
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Old 08-10-2009, 06:30 PM
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We need more information about what is going on before we can try to help.
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Old 08-10-2009, 07:58 PM
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I am using the turbonetics setup:
• T4 E-50 Ball Bearing Turbo
• Spearco intercooler
• Raptor blow-off valve
• Evolution wastegate
• Unichip engine management
• 4 drop-in Motron high flow injectors...if i remember right 600cc

When i turn the key on and step on the gas, the throttle body plate aka the butterfly will try to open or close making this clicking sound for about 10 secs. The ob2 scanner says that its a position sensor and the position sensor on the TB is riveted on. I bought a used one from the junkyard and replaced the TB. Now its still doing the same thing, it makes this clicking noise like its trying to open. So the only thing that comes to mind is check all the fuses and wires.

I all my ign fuses are good. Now for the wiring, i printed out an ecu diagram to help me find out what the standard volts are on the TB. I discovered that the TB sensor is not getting enough power to open, causing it to flutuate and click. Standard volts for the TB sensor when pedal is depressed should be 4.5-5.5 volts mine reads 2.5 when the pedal is depressed. This test was tested on the old TB. The new TB's butterfly is flutuating just like the old one, so nothing changed when i replaced it.

So maybe my TB is still good and there could be a wiring problem somewhere thats causing this. I'm going to check my wires for any shorts..etc. Could this be an ECU problem? Oh i forgot to mention, i checked my cranksensor and it is good. can anyone tell where the cam sensor is? could it be that since my tb is malfunctioning I am not getting any ignition spark?

Thanks for concerns/help

Last edited by den_d; 08-10-2009 at 08:31 PM.
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Old 08-10-2009, 09:18 PM
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cam sensor is on the right side of the valve cover....if u pull the valve cover off and look at the end of the intake cam u will see three pins coming out they rotate around the cam sensor...pretty easy to find.

with the throttle body not working properly im not to sure im sure don will know though.
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Old 08-10-2009, 10:22 PM
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i doubt its a short as no fuses were popped. Check relays. Did you actually pull the fuses out to check them or just check them for continuity? You need to actually pull them out.
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Old 08-11-2009, 08:21 PM
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Yes i pulled them out but i have not checked the relays for continuity yet.
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