Poor Performance
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Joined: Jan 2009
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From: Round Rock
Poor Performance
Hey guys/gals
I have 1989 F-150 with a 4.9 6 cyl 300 4X4 5 speed mazda tranny that is acting up. It starts at the flip of the switch. Engine is not that old (rebuilt) and generally runs fine at a easy acceleration but acts sluggish during a fast or "punch it" acceleration. When I accelerate going through the gears it will pick up at first but then it falls back and struggles or faulters when I try to wind it out like it reaches a peak and then and then labors and looses power. I was a certified mechanic and old school muscle car builder but don't know what is causing this. I know that the timing (initail set with light) is right. Idles like a charm, no overheating, no check engine codes, throttle body clean. no vacum leaks (that I can see or detect). Anyone got a clue? Sensors are practically new all around and exhaust system is new and enlarged except for muffler.
Any help is greatly appreciated.
Thanks
Jim
I have 1989 F-150 with a 4.9 6 cyl 300 4X4 5 speed mazda tranny that is acting up. It starts at the flip of the switch. Engine is not that old (rebuilt) and generally runs fine at a easy acceleration but acts sluggish during a fast or "punch it" acceleration. When I accelerate going through the gears it will pick up at first but then it falls back and struggles or faulters when I try to wind it out like it reaches a peak and then and then labors and looses power. I was a certified mechanic and old school muscle car builder but don't know what is causing this. I know that the timing (initail set with light) is right. Idles like a charm, no overheating, no check engine codes, throttle body clean. no vacum leaks (that I can see or detect). Anyone got a clue? Sensors are practically new all around and exhaust system is new and enlarged except for muffler.
Any help is greatly appreciated.
Thanks
Jim
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Joined: Jun 2006
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From: Ottawa, Ontario
How old are the plug wires? Might be a good idea to inspect them in the dark to see if there is arcing. Also could be a weak coil. Also check the fuel pressure, Should be about 50psi and should not drop under load.
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Joined: Jan 2009
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From: Round Rock
Plug wires are relatively new and both fuel pumps (in tank and on the rail) are not very old but I will check the psi and see what I get. I hadn't thought about the fuel filter but now that you brought that to light I'll check that as well.
Thanks
Thanks
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