Ever since i got the car from my dad, who had it in storage for the passed 2 years, it hasnt had very much power. It still beats the crap out of my moms truck, but like, when i put "put my foot to the mat" it doesnt do any outstanding like i thought a 4.6l V8 would, you know? If i start at 40km/h, and gradually press the gas down, it roars to life, but not as much as i expected even then. When i put it to the mat tho, the RPM's usually shoots like about 3.1k and doesnt really have that much acceleration. Wierd, right? Theres the odd time where it just rips, but not very often.
If you guys want a list of replacement parts ive put into it, which adds up to about $4500 total, i can list them in a re-edit?

~Thanks, Evan

 

The first thing that comes to mind is '97 4.6 liter birds have a primary, and secondary intake runners. At low engine rpm's the air/fuel charge takes one route to the combustion chambers, and at high rpm's they take another, shorter, path.

There is an actuator that opens and closes to direct the two different pathways located to the side of the intake manifold. There are clips on the linkage of the actuator that are well known to break, and thus there is no seconday increase in power since the door/flap never moves. Basically the car runs on the primary pathway all the time.

If you have anymore questions regarding this please don't hesitate to ask. Thus too, I would be very interested in what you find.

 

INFO UPDATE.

The system I refer to is called: Intake Manifold Runner Control, IMRC.

 

I am having a similar problem, but first a little history on the vehicle. Found a '96 4.6L bird with just under 100,000km for 2200$ STOKED! It was a one owner vehicle, older fellow who took care of it, definitely not abused. Shortly after purchasing had a problem with the idle air control (iac). My buddy is a red seal mechanic (and a good mechanic too) so put a new iac in for pretty cheap. Car seemed to run well but I thought it had really long legs with the stock 3.27 rear end. Usually drove it with the overdrive turned off. So, got my buddy to put in new 3.73's. That seemed to make it quite a bit more snappy off the line and now i'm happy with the gear rpm to speed. The strange thing is I noticed how the engine seems to produce more power at a little over 3/4 throttle than right to the floor, especially off the line. At around 3/4 throttle the engine produces good power and the rpms climb steadily until about 3500 where there's a noticeable drop in power. If I put the pedal to the floor to prevent the tranny from shifting into the next gear, or leave the o/d off, the rpm will continue to climb but not nearly as quickly as you would expect. The power simply isn't there, like something is definitely wrong. Another weird thing that happens occasionally is if I'm doing around 60km and put it right to the floor, it will drop down into second and accelerate slightly sluggishly until that 3500 rpm mark and then just stay there until I back off the throttle to 3/4 where it will resume accelerating. From what I've read on this thread it sounds like the intake manifold runner control. I'm somewhat knowledgeable for being a novice mechanic but this is an area i'm not that familiar with. I'm going to get my buddy to help me check out the whole setup with the clips for the actuators and whatnot. If anyone has any additional, specific information or knows of any online resource / diagram to make sure it's properly set up that would be greatly appreciated! Also, if that doesn't turn out to be the problem, is there something else that I should be looking at?

~thanks for any help!
Dusty