Car has took a crap, need help....

[135 Boom]

So I went to drive my car last week and it will not start. Recent mods are LFP throttle body and plenum. I thought it was that, so I put the stock one back on, but it still did not start. It cranks fine and has 13.8 volts. I did some research and thought it was the FRPS, so I replaced the FRPS and put in a KB disc. Still a no go. I looked more and found out if the car is flooded that you should hold the gas down and it will start, so I did that and it fired right up. I let it idle for 5 minutes and shut it off. It idled a little high at about 1200, but it was cold too. Then I tried to start it again and it would not start. I came home for lunch and held the gas down again and it fired right up. So I let it warm up, took it for a .5 mile easy drive, came back and shut it down. Now it won't start again. WTF am I missing? Any help would be appreciated.

 

[ttk53]

Its starts with the pedal on the floor? becasue it shouldn't since that shuts the fuel off.

 

[Riddick]

Did you reset your TPS when you swapped throttle bodies?

 

[03' White Snake]

Did you reset your TPS when you swapped throttle bodies?

Thats what i was gonna say.

 

[135 Boom]

I doubt it. I unplugged the battery and turned the key 5 times to drain the memory. How do you reset the TPS? TPS is the one on the top of the throttle body and IAC is on the side correct?

 

[Riddick]

Yes, thats the one I believe it has three wires going to it, the one you get voltage off is the middle one....... I think. You need a volt meter and should set it to .97-.98v with your key to the on position and engine off. It is a pretty sensitive sensor, meaning the smallest movements will cause the voltage to change. You also may need to file your holes out a little bit so you can adjust it accordingly. Before you loosen the sensor check to see what the current voltage is.

 

[hotcobra03]

Bad plugs...

 

[Weather Man]

Bad plugs...

Yeah, a fresh set wouldn't hurt. They might be fouled from the fuel.

 

[135 Boom]

Yes, thats the one I believe it has three wires going to it, the one you get voltage off is the middle one....... I think. You need a volt meter and should set it to .97-.98v with your key to the on position and engine off. It is a pretty sensitive sensor, meaning the smallest movements will cause the voltage to change. You also may need to file your holes out a little bit so you can adjust it accordingly. Before you loosen the sensor check to see what the current voltage is.

I checked this too. I am certain I was using the correct volts on the meter and it said 5.4. I turned it left and right and it only went up and down .3. I may have messed up the sensor when I put it back in. It felt like there was tension on it when I pulled the stock one off, so when I put the new throttle body on I turned it. After research it was a bad choice, so I am not sure if it is bad or what.

 

[135 Boom]

Bad plugs...

Plugs have 400 miles on them. Pulled the driver side and they looked brand new, so I didn't even check the passenger side. Should I pull the passenger side too, or do you think its ok?

 

[hotcobra03]

I checked this too. I am certain I was using the correct volts on the meter and it said 5.4. I turned it left and right and it only went up and down .3. I may have messed up the sensor when I put it back in. It felt like there was tension on it when I pulled the stock one off, so when I put the new throttle body on I turned it. After research it was a bad choice, so I am not sure if it is bad or what.

Its a 5v sensor..
Google how to test ford 4.6 and 5.4 sensors with multimeter..

plugs..just change all 8..gas can kill a new set on 1 start up.not common but can happen

 

[135 Boom]

Its a 5v sensor..
Google how to test ford 4.6 and 5.4 sensors with multimeter..

plugs..just change all 8..gas can kill a new set on 1 start up.not common but can happen

I found how to test it. I messed with it a lot, so I just ordered a new one.

I don't mind changing the plugs, but it doesn't seem to miss at all when it is running. It actually runs perfect when I get it started. It's just starting it that is the problem. It feels like it is electrical for some reason, like something is not aligned right to allow it to start. When it starts there are no codes thrown either, but the only way to start it is to hold the gas all the way down.

 

[usmc320]

I checked this too. I am certain I was using the correct volts on the meter and it said 5.4. I turned it left and right and it only went up and down .3. I may have messed up the sensor when I put it back in. It felt like there was tension on it when I pulled the stock one off, so when I put the new throttle body on I turned it. After research it was a bad choice, so I am not sure if it is bad or what.

It sounds like your TPS voltage is incorrect. It should range from somewhere around 0 volts (someone else said just under 1V which is probably right) at 0% throttle and somewhere close to but not over 5V at 100% throttle. The numbers you stated indicates a problem, probably a bad or seriously misadjusted TPS. I would focus on that.

 

[135 Boom]

It sounds like your TPS voltage is incorrect. It should range from somewhere around 0 volts (someone else said just under 1V which is probably right) at 0% throttle and somewhere close to but not over 5V at 100% throttle. The numbers you stated indicates a problem, probably a bad or seriously misadjusted TPS. I would focus on that.

Yeah that is what I am leaning towards. Thanks brother.

 

[Riddick]

As stated its a 5V sensor and I bet you were getting your signal from the supply wire. Did you try the other wires on the sensor?

 

[usmc320]

As stated its a 5V sensor and I bet you were getting your signal from the supply wire. Did you try the other wires on the sensor?

Good point. I just assumed he checked the correct wire. Although he still shouldn't have over 5 volts like he stated.

OP - There are probably 3 wires going to the sensor. One is 5V supply (VREF). One is a VREF return (sensor ground), and the other is your TPS output. I would pull the sensor out and test it uninstalled but with the wires hooked up. That will eliminate the possibility of it being installed wrong.

 

[135 Boom]

Good point. I just assumed he checked the correct wire. Although he still shouldn't have over 5 volts like he stated.

OP - There are probably 3 wires going to the sensor. One is 5V supply (VREF). One is a VREF return (sensor ground), and the other is your TPS output. I would pull the sensor out and test it uninstalled but with the wires hooked up. That will eliminate the possibility of it being installed wrong.

I checked the middle wire. That is what my research told me to check, am I right?

 

[135 Boom]

Well the update. I swapped the TPS and it fired up right away. Thanks for all the advice everyone.