Engine lacks power

Tiny
TRAMMELL503
  • MEMBER
  • FORD F-150
1997 f-150 258,000 miles but rebuild at 135,000. The problem started a couple weeks ago. Sometimes when I would acllerate I had to put the pedal all the way to the floor in order to get any kind of momentum. I took it to the ford dealer and they said it was the catalytic converters. Replaced them. Runs somewhat better but still lacks power. With the ac on it really bogs down. I have replaced 2 of the o-2 sensors the maf. Also when you race the engine in neutral and let off the gas it will backfire. I know the dpfe needs replacing. But the ford mech said that would not cause my problem. It runs the same whether the shorting bar for the pcm is in or out. When this first started it would only do it for a second then run fine. Any advice would be greatly appreciated.
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Thursday, August 9th, 2007 AT 4:08 PM

4 Replies

Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Have you checked the fuel pressure? Has the filter been replaced recently?
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Thursday, August 9th, 2007 AT 4:34 PM
Tiny
TRAMMELL503
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Fuel pump and filter have been replaced. Also engine run s good when cold, and also at higher rpm and during about 30 seconds after start up. I'm sorry this is a 4.2L engine thanks for your patience.
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Saturday, August 11th, 2007 AT 5:28 AM
Tiny
2CARPRO JACK
  • MECHANIC
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Be nice to get it on a scanner to see if you have a TPS that is going out. Did it have any codes pertaining to the TPS?
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Sunday, August 12th, 2007 AT 8:35 AM
Tiny
ROLLBAR
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Just a reply. I also have a '97 F-150 & it was doing the same thing then quit. Came out to be the fuel pump. Since U already changed it out I would agree it could be the TPS. AZone will put it on the scanner for free, @ least it's a start, that is if it's trowing a code.
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Sunday, August 12th, 2007 AT 8:39 PM

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