Hesitation/missing with A/C on

[bocefas]

I recently bought my late Uncle's 2001 B3000 (which he bought new) and I have been trying to learn to love the 3.0 engine. It is 4WD and an extended cab, so I am not expecting a whole lot, but I will admit every time I drive it I find myself thinking real hard about turning into a B5000. Anyway, I have noticed an appreciable loss of power and a miss/hesitation at highway speed with the A/C on. The truck has 106K on it, but has been babied its entire life. It had plugs, wires, and the coil replaced about 10k miles ago. I ran couple of tanks of premium through it and added seafoam to one of those tanks. I read on here that the 3.0 likes to rev, so I have been revving it much higher than Uncle Steve would ever let me before(3 grand was his redline) between gears. Without the A/C on it seems to run smoother than it does with it on. 5th gear level road 60 mph with the A/C off it is just dandy. Reach over and turn the knob to A/C, the miss starts. It misses consistently across the rpm band, I mean to say if I downshift into 4th and accelerate it still misses.

Well I am starting to ramble but any ideas as to the cause?

Thanks!

 

[downzero]

When you figure it out, please let me know. Mine misses pretty bad at idle and I think it's the valves. It has about 200k on it, and it actually still gets 20 mpg and drives fine, it just has no power.

 

[Froggmann]

Get an underdrive crank pulley, it reduces the drag/impact A/C introduces to the system. It'll also free up a bit of power and fuel economy. If your truck is flex fuel, run a couple tanks of E-85 through it. It does wonders for cleaning the fuel system and making the engine run much better.

A good running 3.0 w/a couple simple mods will yield good mileage and decent power.

 

[Rearanger]

any ideas as to the cause?

Not yet, but it would be a good idea to see what your hot engine compression is. You need to know that before trying to figure out what else it may be.

An A/C compressor with a bad bearing that creates excessive drag could also account for it but I'd think you'd hear unusual noise from that.

My truck's power is fine with A/C on so for now I'd stay away from undersize pulley to compensate for what may be a mechanical problem.

 

[JP02XLT]

I just fixed a Taurus that had a similar problem, 3 other shops had looked at, they did plugs, wires, injectors, and several other attempts at replacing various sensors. The vehicle only missed under load, I checked the ignition coil and found 1 bank on the coil to be out of spec on the secondary side of the windings. Replaced the coil and the miss went away, idles great and his fuel mileage went back up.

JP02XLT