Ive noticed with my truck under hard acceleration there seems to be a hesitation if you want to call it that. Accelerates good till it hits 2500rpm then power seems to drop and come back around 2700rpm. Not really noticeable in 1st or 2nd but its definatly there in 3rd/4th.

No codes (yes I checked lol)

Is this just something normal for a stock 351?

95 f150 4x4 451 e4od

 

i think it is just normal my truck also is like this

 

That's not normal IMO, I'd suspect plug wire cross firing so maybe try re-routing them to see if it makes any difference.. paying particular attention to #5 and #6 which follow each other in the firing order, and also that the wires aren't contacting metal engine components. Hard to do? Yes.. some plastic wire loom helps protect and space the wires where they overlap and touch the engine.

 

Oh boy this could be fun. Thanks Paul! I'll try that this morning

 

Well It wasn't do bad, they're all separated now, hard part was getting the 9mm ford racing wires into the holders lol

Still the same thing. It's almost like I let off the throttle for that short time and then hit it again. The exhaust gets quieter during this hesitation as well then picks right back up again

 

I have msd coil, cap/rotor a the ford 9mm red wires. Motocraft plugs at 65thou gap(IIRC) and timing at 13.5*

 

AnyBody have any other thoughts on this?

 

you must have a tach if you can notice at which rpm this happens. does the tach slow it's accent between those two rpm's? when the tach picks up again does the engine downshift? PCM maybe?? If you get to this rpm threshold and floor it what happens?

 

What tranny, gears and tire size are you running? It could just be that this is a difficult spot for your pcm to determine how much fuel and air are required to accelerate smoothly because it was designed with factory everything in mind and you have custom settings and equipment.

 

When it is floored and accelerating most noticeable in 3rd gear and some in 4th.

I have the factory tach and it seems to slow down between 25-2700rpm. And it will up shift around 4000 with the pedal to the floor

 

5.8l E4OD 3:55 gears
It was the same way stock no lift and stock tires as it in now with the 33" tires

 

"it will up shift around 4000 with the pedal to the floor" .........It doesn't have much choice but to shift up at this point. It could be that you are at the limit of your machine. It doesnt sound like you are losing power, just not getting it as fast in a higher gear as in a lower gear. That doesn't seem unreasonable for an older truck. Add a pint of seafoam and see what happens.

 

It pulls hard except between 2500-2700rpm. It's like someone turns down the power a bit till 2700rpm then it picks back up and pulls hard again

 

I'd try the seafoam, then start thinking about the pcm if that doesn't work. Reading off of the back of the Seafoam can in my hand "when added to fuel line, vacuum or induction cleaning systems.......cures hesitation and ping" It doesnt sound like an engine issue if there is 0 hesitation in low gear at the same rpm. The engine does what the pcm tells it to do if it can. Who knows what all the ethanol and crap in the gas are slowly doing to our older vehicles.

 

Yeah I'll give it a dose of seafoam and see if that helps. It honk the hesitation is still there in lower gears just less noticeable due to TW lower gear.