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Loss of power on acceleration 03 150 4.6

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Loss of power on acceleration 03 150 4.6

 
  #1  
Old 01-29-2011, 06:56 PM
THE DAVER
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Loss of power on acceleration 03 150 4.6

Driving the other day and it started that when i step on the gas i have no power it idles ok. and runs fine at slow and freeway speeds.Thru a set of plugs in as i havent done that fore awhile. Its like im towing a heavy boat when i step on it. Any ideas. i drive it as a courier every day its a 03 F150 4x4 with a 4.6 and next week it will turn over 400,000 miles and i do all the work myself.
 
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Old 01-29-2011, 07:11 PM
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I was also wondering if the whole EGR system could be causing this
 
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Old 01-29-2011, 08:28 PM
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If you have no "check Engine Light ' on, you pretty much have to suspect a lot of possibilities. Really dirty air cleaner, contaminated MAF sensor, dirty throttle body, plugged fuel filter, TPS sensor ( although this would normally throw a code), possible vac line problem to the fuel pressure regulator. Pretty endless list. With that many miles, lot's of things could be starting to wear or stick, or work good enough to not trigger a code, at least right away.

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Old 01-30-2011, 09:24 AM
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It had a light omn but i thought it was from tha slow movimg iacv so i unplugged the battery wihile i was replacing the spark plugs. Only put about 10 miles on since and no light yet. im sure it will trigger it on shortly
 
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Old 01-30-2011, 10:13 AM
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With that many miles on it,I would look into the Catylictic converter(s).
Granted,evidently you have no cel pointing to this,but over time converters can plug up causing an exhaust restriction.If the truck cant push out the exhaust relatively un-restricted,it will definately cause "degraded" performance...especially at higher speed demands......
 
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Old 01-30-2011, 11:25 AM
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ok im gonna go run it into town. Is there a good way to check the cats with out dropping the exhaust. I was gonna doit yesterday but got just to damn cold
 
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Old 01-30-2011, 11:43 AM
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Daver

If it's the cats, and you have a vac gauge, just plug the gauge into a line, after you start the engine and it's run for a couple of minutes. Whatever your vac reading is, it will gradually drop as the exhaust starts to back up from a potentially plugged cat.

Dave
 
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Old 01-30-2011, 11:50 AM
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I remember(Years back) watching a mechanic measuring the inlet temp as opposed to outlet temp on the converter.If memory serves (in the case of a restricted converter) the inlet temp will be much higher than the outlet temp...I suppose indicating internal restriction.
 
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Old 01-30-2011, 12:52 PM
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Ok thanks i dont have any drop in vac wich will probably elimanate at least a totally plugged cat.It kinda started like something quit working. Im heading to town now to grab a new fuel filter. As it needs one anyways. maybe starving for gas.And maybe thie light will come back on. it about a 30 mile round trip Any chance a cop could have failed and wont fire on anything at high rpms. My buddy has a couple of good ones i can grab and switch around.
 
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Old 01-30-2011, 01:25 PM
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Cop's show failure signs either under acceleration or under a load on the engine (or higher RPM's). If you don't yet have a misfire code with the cyl #, you will have.

Dave
 
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Old 01-30-2011, 11:04 PM
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80 miles on and no light. Idles at 750 in park 650 in gear and as smooth as a new truck. I can make the rpms go as high as i want just not alot of acceleration. Doesnt seem like the tranny is slipping but kicker down she switches gears rpm goes up just not alot of pull.No vac problems but took one hose off from riser pipe to dpfe and now if i kick it down it will pop off.makes me wonder how much pressure should come up that and is it supposed to return on the other. Might not even matter just thought it was weird.
 
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Old 01-30-2011, 11:57 PM
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Any chance the tailpipe got bent over ?

All the computer stuff aside, lacking anything to go on, all you can do is start testing parts. I've had plenty of electrical parts "bench test" good, only to fail when put back in place.

Assuming the trans and converter are functioning correctly, it just sounds like something is out of sync with the speed and RPM's, like spark advance, or fuel charge. It's apparently only sluggish under load, and fine the rest of the time. Sounds like one of those times where it needs to be plugged into a computer that can monitor the whole system, while it's running, and ideally working the throttle to see what changes.

Dave
 
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Old 01-31-2011, 08:46 AM
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Yep i think i agree my nieghbor is a chev mech at a dealership so when he get home from his weekend i will see if he can run it on his scanner for me. All thing a side from that part store was out of fuel filters said they will have them in today. think a plugged one would cause this. it would be kinda cool if that all it turns out to be. And by the way thanks
 
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Old 01-31-2011, 03:37 PM
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Yes it could. At high fuel demand loads, volume would be cut way back.

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Old 02-03-2011, 09:45 AM
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Here is an update monday am fuel pump died. Fixed it and put new filter in. Well it runs really good but still got the same issue. Took it over to the neighbor (chev mech.) put a gauge in thru the o2 sensor holes passenger side is fine drivers side needle moves all over. He didnt trust his gauge so he was bringing his new one home from the shop today. but after a drive he is pretty sure its a plugged cat. Gonna check it on the new gauge and plug it in to his scanner tonight. If plugged can i just gut out both of them and will the motor run properly. we have no inspections here in MN
 

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