speedfreak2685

iTrader: (12)

I had (well still do) a po121 tps code pulling up on the scanner so I replaced the tps sensor with a new one and it did'nt fix the problem at all. The car every once in a while will "break-up" when leaving from idle. it does it about 1 out of 20 times leaving from ilde just to give you an idea. sometimes it will do it 2-4 times back to back. You have to mash the pedal to the floor to get it to "clear up". The motor has been out of the car once and the intake manifold has been off the car 3 times so the only thing I could think of is maybe it pinched a wire or something and is getting a intermitent signal every now and then. I was going to try to trace the wires going to the tps sensor but my question is where do the wires go after they leave the sensor. I know they run along the fuel rails towards the back of the intake manfold but where to from there? Anyone else have any ideas to try?

speedfreak2685

iTrader: (12)

Anyone?

XpEdItIoUs

iTrader: (44)

TPS uses a 5-volt reference, ground, and signal circuit. signal voltage should be at 0.6 volt at idle and 4 volt or more on WOT. The PCM compares actual throttle position from the TPS to a predicted throttle position value calculated from engine speed and MAP sensor Input.

First you check MAP sensor voltage on idle and with the engine RPM increased to 2000 RPM if you see voltage change, check signal voltage on the TPS, It should be less than 1 volt and 4 volt or more while moving the accelerator pedal from closed to wide open.

If you don't get a voltage change disconnect the connector from the TPS and check for signal voltage it should be zero. Use a fuse jumper from the 5-volt reference to the signal voltage. If you see 5-volt on the signal circuit your TPS is bad if you don't see any voltage check the TSP 5 volt reference/signal circuit for pulled pinched wires and the TSP ground for high resistance.

I Hope this helps your in diagnostic, If you get no voltage change on you MAP sensor let me know and I will help you with that.

Gray wire is 5v reference, green is sensor signal circuit and black is ground on the TPS harness.

Hamrdown

iTrader: (25)

Also if you've done the bump stop mod on the tb due to porting or whatever then the blade might be opening up too far and it can throw this code. You will need to back probe the tps sensor and it should not read past 4.7 volts at WOT. If it does then you need to drill and tap the back stop and put in a set screw and adjust to no more than 4.69 volts. I had mine ground down too far and it was actually breaking the pot (tps) sensor and would give me erratic readings as I would open the blade.

speedfreak2685

iTrader: (12)

Everything reads fine on both the map and tps as far as voltage goes. This problem just happens every once in a while like there is a cut or pinched wire and is getting a intermitant signal. Thats why I need to know where the wires go to after they leave the tps and route along the fuel lines so I can trace them. I wish I had a way to date-log the problem when it happens but I don't.

JonCR96Z

iTrader: (33)

I overheard someone talking about a TPS sensor at the TFB meet last Friday. Was that you?

CashDudeHomie

iTrader: (5)

So if my 2000 Silverado 6.0 is showing .33 Volts when the TPS is at 0% then the TPS is probably bad?

It should be closer to .6 volts, correct?

OUTLWZ

Did you change your cam?

My car keeps getting the PO121 code also. But its due to the cam I have and the map volumes being set to high. My car is going back to the tuner monday.

CashDudeHomie

iTrader: (5)

BUMP 5 char