Loss of power after warming up
#1
Hi guys, I have an 07 5.4 that when cold runs good but as soon the temperature needle reaches normal running temp the truck starts running like crap. It loses power considerably, it will reach top speeds (70/80+Mph) but you kinda have to floor it to get there. Previous owner said that had the cam phasers replaced and so far I've replaced the following: Spark plugs (motorcraft), coil packs, knock sensors, whole intake manifold and oil change at the dealership. I just don't know what else to do, just purchased the truck month and a half ago and already have so much money into it that's not funny. Don't think I can spend more money in this truck, it's driving me nuts. Any ideas what could be causing this problem? Thanks for your help!
Last edited by Christiancito; 11-25-2015 at 10:42 AM.
#2
Clean the throttle body if you haven't already. Make sure the cleaner is spec'd as safe for Teflon coatings. Confirm the foam on the air filter is good. Make sure to use an oem filter. I used a K&N and it wasn't sealing properly. Also do a throttle body reset. Search through the forums and you'll find that procedure. It's the one that involves turning the key, slowly pressing the gas pedal to the floor and quickly releasing. Also make sure all plugs are torqued down properly (33ft-lb). If you're hearing a ticking sound it could be associated with a lose plug. Mine had the same issues and completing the above checks resolved all my issues. A bit of a pain but these are fairly inexpensive checks you can do yourself before you get into the more expensive options.
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Christiancito (11-24-2015)
#3
Clean the throttle body if you haven't already. Make sure the cleaner is spec'd as safe for Teflon coatings. Confirm the foam on the air filter is good. Make sure to use an oem filter. I used a K&N and it wasn't sealing properly. Also do a throttle body reset. Search through the forums and you'll find that procedure. It's the one that involves turning the key, slowly pressing the gas pedal to the floor and quickly releasing. Also make sure all plugs are torqued down properly (33ft-lb). If you're hearing a ticking sound it could be associated with a lose plug. Mine had the same issues and completing the above checks resolved all my issues. A bit of a pain but these are fairly inexpensive checks you can do yourself before you get into the more expensive options.
them to specs. Thanks! I will see of that helps!
#4
Easy things first, engines need fuel, spark and air. A reduction in any of these will hamper performance. Nyles has some great tips. I would add (if I didn't miss it) fuel filter and FPDM under your spare tire. If this is a new vehicle to you the FDPM should be inspected by you anyway. I'm assuming your fuel tank has been filled with quality fuel recently. Im certainly no expert but one other thing I can think of is the VCT solenoids as I know they begin operation at a certain engine temperature. Again, full disclosure, my knowledge on this is weak at best. Sorry I can't be of more help.
Dev
Dev
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Christiancito (11-24-2015)
#5
Easy things first, engines need fuel, spark and air. A reduction in any of these will hamper performance. Nyles has some great tips. I would add (if I didn't miss it) fuel filter and FPDM under your spare tire. If this is a new vehicle to you the FDPM should be inspected by you anyway. I'm assuming your fuel tank has been filled with quality fuel recently. Im certainly no expert but one other thing I can think of is the VCT solenoids as I know they begin operation at a certain engine temperature. Again, full disclosure, my knowledge on this is weak at best. Sorry I can't be of more help. Dev
Tank is almost empty and will fill it up with good quality gas. Ive had this truck for a little over a month, so this is a new vehicle to me. Will check fuel filter and FDPM (whatever that is lol). VCT sounds logical too cuz it starts running like crap ONLY after its warmed up, when cold, it runs good. Thanks for your input! 👍
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Christiancito (11-24-2015)
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Christiancito (11-24-2015)
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Christiancito (11-24-2015)
#9
#10
I used it cuz im dumb man... Never again... Catalytic might be another cuase, sounds about right, that might explain why it losses power only when warm