Hey guys, I have a 2001 f150 xlt 4.6. I fixed the stumbling problem it was having but now when i come to a stop at a light my rpm's will go below 500 and then the truck will vibrate. Recently ive cleaned the MAF, TB, egr ports and egr. Ive also changed fuel filter, IAC, TPS. I replaced all my 02 sensors within last 4 months. Any ideas would be great. It also seems to have lost some power. Thanks

 

??

 

Maybe the TPS is adjusted wrong?
Check your voltage.

Only thing I can think of.

 

How do you adjust the TPS. I couldnt get a voltage from the back but when i took it off and checked it from the inside it was 5. I know it supposed to be checked also when the pedal is pressed but i couldnt get a reading from the back probe. ????. Any other ideas?

 

Do you think the Bosch O2 sensors could have gone bad?

 

How old are they?

Generally speaking, I believe most people use the Bosch O2 sensors as replacements anyway.

 

TPS seems to be right. Maybe this is the low idle everyone talks about being normal to save on fuel usage. My superchip and intake ought to be here this week; hopefully the chip will fix the idle. I might also go ahead and change plugs. ONly 55,000 miles though?

 

I was just going to suggest to check your plugs. See if they are loose before just cranking them out. Try to remove them w/o a wrench on it. If you have a torque wrench, adjust to 12lbs and try to remove them. If they won't come out, then they were tight. The problem I had was exhausting through the plug threads because they were loose (creating a rough idle). Check the carbon trail if it is black up all the threads or just toned. Also, if the COP boot is discolored rust to yellowish, that may be signs of exhausting through the plugs. When you put the new ones in, I would suggest using a torque wrench, adjust to 13 lbs. If you had really loose plugs, your threads are probably damaged. Yes I just blew a plug and I am probably just paranoid, just trying to pass on the info from the experience that I just had.