Pathfinder runs fine until 2800 RPMs!
For all you motorheads out there, here is a question that has left me and many mechanics absolutely baffled...
I own an '88 Pathfinder, V6 (throttle body injection), with 110K miles. I drive it daily, and it runs fine. Overnight, the following problem surfaced - the engine sputters at 2800 RPMs and wont go past that mark! It idles real nice runs absolutely fine before it reaches that mark. It doesnt matter what gear I'm in, what kind of load its under, the position of the throttle (which rules out the throttle position sensor, right?), the engine runs fine exactly until it reaches 2800 RPMs, and then begins to sputter and jerk until I lay off the throttle. (Although it seems to have a little less power and might miss while going up steep hills)
There are no vacuum leaks I've found, no obstructions in the exhaust (I temporarily disconnected the cat, and the problem doesnt go away) From a visual inspection, the injectors are getting plently of fuel at the point of sputtering. I changed plugs, wires, and cap, without solving the problem. What could the problem be?
Although, by use of the throttle, the engine wont go past 2800 RPMs, I was able to get it past that mark by downshifting while going down a steep hill. Here's what happens: the engine still runs above 2800 PRMs, though pressing on the gas pedal has no effect, save a slightly different sound from the engine. As the engine slows to 2800 RPMs, pressing on the gas will cause the violent, on-again off-again jerking, until it goes below the mark and runs fine.
I am at my wits end! If anyone knows a quick fix, or if this is a common problem with the old Nissan V6s, please let me know. Thanks!