02 F150 4.6 RPMs drop while under power
#1
12-04-2020, 11:43 AM
02 F150 4.6 RPMs drop while under power
Hey guys,
I'm new to the forum and sorry if this is the wrong place to post this, but I need help!
I have an 02 F-150 XLT Super Crew with the 4.6 in it. It has over 200k on it that I have owned for over 1 year and it ran like a champ the whole time. I am the 4th owner. Just within the past couple of days it has been giving me problems. It started with running rough while in drive at a stop light. Then it started dying at the stop lights after it would run rough. IT would stop doing it if the truck was at operating temperature and only seemed to do it if it was cold. Now, just yesterday, I went out and got in it to go to work, and it was running rough while in park. I let it warm up and put it in reverse. It acted like it didn't want to move. I gave it some gas and it began to back up. I then put it in drive to be on my way, and it acted like the parking brake was on because it began to move but not like it usually does. I gave it more gas and the ABS light came on and the truck began to move. The ABS light stayed on the whole time after. I was running late for work, so I thought I would check it out after work and just continue to work. Once I started down the road, I could hold the gas pedal down for about 5 seconds and then the RPMs would drop from about 2500 to about 600. I thought that it was just cold so I stayed in the pedal to hope it would push threw it. The RPMs stayed low until I let off the pedal and then reapplied the gas. I tried giving it power again and it would go and the RPMs would climb for about 3-5 second and then fall out again. It did this my whole way to work where I would push the gas for about 3-5 seconds and the RPMS would fall until I let off and reapply the gas. Where the RPMs were didn't matter. After they fell one time, I floored it and the transmission kicked down and the RPMs went to about 4000 and ran great for about 3-5 second and dropped again. The gear doesn't matter either. It will get up to highway speeds, but only if you are willing to play it's little game. I am completely stumped.
during this ordeal I have replaced:
TPS
Fuel pump
Fuel filter
Idle air control sensor
MAF sensor
The other weird thing about this problem is that it is not throwing any codes. This is driving me nuts. I am by no means a mechanic but I do know basic maintenance and I do all my own repairs. Everything I know how to do, which isn't very much, I learned on YouTube. I am about to pull my hair out because this has been such a great truck and I love it. It's my first truck. Sorry this post is so long. I'm at the end of my rope. Any help is greatly appreciated.
I'm new to the forum and sorry if this is the wrong place to post this, but I need help!
I have an 02 F-150 XLT Super Crew with the 4.6 in it. It has over 200k on it that I have owned for over 1 year and it ran like a champ the whole time. I am the 4th owner. Just within the past couple of days it has been giving me problems. It started with running rough while in drive at a stop light. Then it started dying at the stop lights after it would run rough. IT would stop doing it if the truck was at operating temperature and only seemed to do it if it was cold. Now, just yesterday, I went out and got in it to go to work, and it was running rough while in park. I let it warm up and put it in reverse. It acted like it didn't want to move. I gave it some gas and it began to back up. I then put it in drive to be on my way, and it acted like the parking brake was on because it began to move but not like it usually does. I gave it more gas and the ABS light came on and the truck began to move. The ABS light stayed on the whole time after. I was running late for work, so I thought I would check it out after work and just continue to work. Once I started down the road, I could hold the gas pedal down for about 5 seconds and then the RPMs would drop from about 2500 to about 600. I thought that it was just cold so I stayed in the pedal to hope it would push threw it. The RPMs stayed low until I let off the pedal and then reapplied the gas. I tried giving it power again and it would go and the RPMs would climb for about 3-5 second and then fall out again. It did this my whole way to work where I would push the gas for about 3-5 seconds and the RPMS would fall until I let off and reapply the gas. Where the RPMs were didn't matter. After they fell one time, I floored it and the transmission kicked down and the RPMs went to about 4000 and ran great for about 3-5 second and dropped again. The gear doesn't matter either. It will get up to highway speeds, but only if you are willing to play it's little game. I am completely stumped.
during this ordeal I have replaced:
TPS
Fuel pump
Fuel filter
Idle air control sensor
MAF sensor
The other weird thing about this problem is that it is not throwing any codes. This is driving me nuts. I am by no means a mechanic but I do know basic maintenance and I do all my own repairs. Everything I know how to do, which isn't very much, I learned on YouTube. I am about to pull my hair out because this has been such a great truck and I love it. It's my first truck. Sorry this post is so long. I'm at the end of my rope. Any help is greatly appreciated.
Last edited by Thomas Castillo; 12-04-2020 at 12:12 PM.
#2
12-04-2020, 01:32 PM
If you can , get hold of a fuel pressure tester. Connect it to the schrader fitting on the fuel rail and watch the pressure. Note pressure at idle and 2000RPM. Then if possible place the gauge where you can see it and take it for a short drive and watch the fuel pressure. If possible either you drive and and have a second person watch the gauge or switch places.. Do not attempt to drive and watch the gauge at the same time, not smart !!
Let us know what you see as far as fuel pressure goes .
Fuel press should stay in the 30-45 range.
Let us know what you see as far as fuel pressure goes .
Fuel press should stay in the 30-45 range.
Last edited by hanky; 12-04-2020 at 01:45 PM.
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