Losing Power
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New User
Joined: Aug 2009
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From: Missouri
Losing Power
I have a 2001 F150 Supercrew with a 5.4L and its losing power more and more everyday. I have changed out the following. Spark plugs,fuel filter,transmission filter, oil filter, pcv valve, re-studded the ex. manifold (Because some of them where broke off), air filter and had it hook up to a computer and had a fuel pressure check done on it. (32 psi). Its going in tommorrow for the o2 sensors to be replace but I don't think it will change much if any. Right now its not setting off the check engine light so there are not any codes. Even the mechanic working on this is puzzled. So does anyone have any idea's on what it might be. 
Elder User
Joined: Jun 2004
Posts: 747
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From: Pelahatchie, MS
Everything that comes to mind should trip the check engine light. Have you ever had any fuel rich problems that could've affected the cats? Has your mechanic checked to see if there any pending codes that haven't tripped the light yet?
Can you describe what you mean by losing power?
Can you describe what you mean by losing power?
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New User
Joined: Aug 2009
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From: Missouri
By losing power I mean that going up a hill no matter how big or small it is it seems to be sluggish. When you take off from a dead stop the truck takes off real slow like its tring to decide if it wants to or not. As long as you give it alot of pedal it just dosent want to go. Compared to most 5.4 this drives like a worn out 6 cylinder. As for code nothing was there, I was hopeing for some old code to show up that would give me a starting point but no luck. Plus my truck is only getting around 8 to 10 mile to the gallon compared to 16 to 18 like it was. Could it be a clog cat.
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Joined: Sep 2009
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I feel your pain rhoads i have a 99 5.4 with the same exact problem. I ve done the same thing to mine that you have done, with no change in engine condition. My next try was going to be to drill some hole in my exhaust before the cats to see if that fixes my problem. please post if you get it figured out!
Elder User
Joined: Jun 2004
Posts: 747
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From: Pelahatchie, MS
I've seen clogged cats before. Literally. When they're clogged, you can visibly see the damage. I was able to eyeball mine when I had my engine out. I would think it should be possible to separate your head pipe from your exhaust manifold enough to take a peek in there, maybe with a mirror.
And off on another wild idea.... Is it possible it could be your transmission slipping?
And off on another wild idea.... Is it possible it could be your transmission slipping?
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Postmaster
Joined: Oct 2009
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Ok, you need a mechanic who goes beyond the codes. What is the long term fuel trim. That one value will tell the whole story whether there are codes or not. There will be separate LTFT values for each bank, and their relationship to each other can help isolate the problem.
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New User
Joined: Aug 2009
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From: Missouri
I will have them check the cats to see if they are clogging. Plus I will have them look up the long term fuel trim and see if they can tell me if it been running rich or not. I have had the MAF sensor cleaned but that didn't help. I have to pick up the truck later today, when I do I will talk to them about everything you guys have said and see what we come up with. Thanks for all the info. Ware8083 as soon as I find out what the problem is I will post it. Again guys thanks
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