95, running sluggish, slow to shift

[Ravenstable]

This looks like a neat site - sorry it took a problem to bring me here. My 95 has nearly 300,000 miles, I've had it almost five years, and had the transmission rebuilt 3 years ago, just to give a little background. Over the last couple months, it doesn't seem to be running well. It starts fine (replaced the start at Christmas), and idles fine, but it doesn't pick up speed like I think it should, and it seems to rev more than it should before finally shifting - I've almost gotten in the habit of releasing the gas pedal to get it to shift. It also sounds like it's working hard to get up to speed, if that makes sense - I just drive it, I'm no mechanic. I think the mpg has gone down, but neither the gas guage nor the speedometer are accurate (the speedometer often doesn't register until I get it up to 40 mph or higher), so it's hard to be certain. I would really like some input before I take it to a shop (if I can find one well-recommended!) and say, "I don't know what's wrong". I'd rather not hand someone a blank check like that. Oh, I did listen for the fuel pump, and it kicks on every time the ignition switch is turned to power. I love my Pathfinder, and just want to keep him happy for as long as possible.

[enkrypt3d]

Is the POWER button turned on? (The button to the left of the steering wheel) this button makes the trans hold each gear a bit longer before it shifts to a higher gear...... I like it on when I'm in traffic or going up hills as it lets me use the gears longer before the trans decides to shift before I'm ready.

 

also might be time for a tune up - new spark plugs, wires, coil, air filter, fuel filter, oil change and if that doesnt help get a new MAF, O2 sensor, PCV and get some seafoam and run it through the entire engine.

 

I poured mine through the PCV hose and into the oil, and into the gas tank.

Edited May 12, 2014 by enkrypt3d

[Precise1]

 

t starts fine (replaced the start at Christmas), and idles fine, but it doesn't pick up speed like I think it should, and it seems to rev more than it should before finally shifting - I've almost gotten in the habit of releasing the gas pedal to get it to shift. It also sounds like it's working hard to get up to speed, if that makes sense - I just drive it, I'm no mechanic. I think the mpg has gone down, but neither the gas guage nor the speedometer are accurate (the speedometer often doesn't register until I get it up to 40 mph or higher), so it's hard to be certain.

Yep, when is the last time it got tune up parts, specifically the plugs, wires, cap and rotor? Other thing would be to check the timing, 15* BTDC. Slightly more advanced but not hard at all is to check the ECU for stored fault codes (write up in the Garage/How To section) and maybe check the output of the TPS (Throttle position sensor). The FSM (Factory Service Manual) can be downloaded from the thread pinned at the top of the Garage section...

 

G

[Ravenstable]

Is the POWER button turned on? (The button to the left of the steering wheel) this button makes the trans hold each gear a bit longer before it shifts to a higher gear...... I like it on when I'm in traffic or going up hills as it lets me use the gears longer before the trans decides to shift before I'm ready.

 

also might be time for a tune up - new spark plugs, wires, coil, air filter, fuel filter, oil change and if that doesnt help get a new MAF, O2 sensor, PCV and get some seafoam and run it through the entire engine.

 

I poured mine through the PCV hose and into the oil, and into the gas tank.

Thanks for the advice. I will check the Power button. I'm not really sure if it's "on". It flashes sometimes, so I looked it up in the manual, but I don't remember that being at all helpful, or clearing up the mystery of what the letters on the button mean (it doesn't say on/off as the options). What option am I supposed to have it set to?

I am planning on changing the plugs and all this weekend. I'm pretty ignorant about cars, but I'm working on it - I didn't know there was an MAF sensor or what it does, but I'll check on that.

[89Rotary]

Heres some basic photo's

 

[Slartibartfast]

The flashing power button means there's a stored code for the transmission. That's worth looking up again... it could well be the cause of your issue, if the trans is slipping or the torque converter is failing.

 

My power switch shows "auto" and "power," and I keep it in "power" pretty much all the time. IIRC for the test, you put it in Auto, then turn the ignition on and count the flashes and pauses.

 

Also, the MAF sensor: the Mass Air Flow sensor has a couple little wire filaments that stick into the intake (just after the filter box). The wires are electrically heated. Electrical resistance through the wires varies with heat, so as air flows past the wires and cools them, their resistance changes, and the ECU picks up the difference in current through the sensor. It sounds imprecise as hell but it's good enough for the computer to figure out how much fuel to inject. A couple things tend to make them flake out. One is junk on the filaments (from oiled filters especially), which you can clean off very gently with contact cleaner or alcohol (nothing corrosive or that leaves a residue). The other is the wiring. The plugs can get corroded (to take the plug off, you have to get that little wire clip off of it first) and the ground wires get gimpy sometimes. A crappy ground connection, corrosion, or fouled filaments will cause the sensor to read incorrectly, and the air/fuel ratio will get buggered up.

 

Doesn't sound to me like the engine's the issue, although it wouldn't hurt to check your throttle position sensor, since it's one of the things that tells the trans when to shift.

[Alkorahil]

As others have said on this, a good cleaning and full tune up can do wonders for these vehicles.