Hey guys...been coming here every now and then to find answers for problems but I hope someone can help diagnose this one for me. I don't have a ton of experience in mechanics so please bear with me.

My '90 4runner (auto and V6) has this random problem accelerating. Sometimes it works great, and the pedal sensitivity works well for downshifting the transmission. Other times however, I have no power at all. Pushing the pedal to the floor does nothing, and I'm doomed for climbing a hill at 30-60 km/hr until I get to the top. Shifting from "L" to "2" and then to "D" does make a change and I can get going faster....but starting off in "D" has no power.

I originally thought it was a transmission problem. My old transmission eventually lost reverse so I swapped it out for a slightly used one, but the problem still persists. The truck works like it's supposed to about 30% of the time.

The transmission fluid looks good and smells nice, the coolant and oil look good (no head gasket problem as far as I can see). The battery was drained completely after sitting a couple winters ago but I've been using it fine for a year and a half. Occasionally when I start all I get is a click, and I have to clean up the positive terminal...then it works fine. Oh, and the battery meter on the dash moves when my turn signal is on. Could it be a battery problem?

If anyone has any ideas I would love to hear them! Thanks...

 

Oh I also forgot to mention that sometimes it can't decide if it wants to downshift or stay with no power...the truck hesitates and jerks around.

 

Sounds like you need a Prius...





lol jk guys

 

if its the motor thats causing this i would inspect or replace the air filter sparkplugs, wires, cap, rotor ect. after that if your still having problems break out the ohm meter and your fsm and start testing .(afm, tps coolent temp sensors and all that jazz)
-hope this helps

 

Hmm that's a good idea...I've replaced the air filter but haven't gotten that heavy into anything else...

 

If it's a random issue, then it won't be the ignition system... More than likely it's a tranny issue.... Somewhere in the shift solenoids, or the CPU.... First guess it's the solenoids! - Try shifting manually through the gears and see what happens!

 

My 92 4runner with a 5 speed once had an issue going uphill. It'd buck and miss and loose power. The spark plug wires were leaking and it only showed going uphill. Replaced them and it went away. It'd be good to do the plugs, wires, cap, and rotor if they haven't been done in a while anyway, as stated above.

 

Thanks for the suggestions guys. I looked at the wires and plugs and they all look fine...both were changed not too long ago. What are the chances of this same problem happening with both transmissions? When I shift manually through the gears like from D down to L, then to 2, it definitely kicks it up and gives some power.

One thing I forgot to mention is that last year while driving about 70mph, the tachometer was going crazy...up and down around 1-3000 rpm's, then eventually stayed at 0. The engine and transmission weren't doing anything out of the ordinary though. It hasn't done that since either...

 

try replacing the speed sensor off the Xfer case. If you don't have a speedometer cable then you have a speed sensor that has been known to cause issues (like the bouncy tach). Take the speed sensor off the Xfer case and clean it up and see if any Tranny fluid is leaking past the O-ring. Clean off the magnet and reinstall and see how it runs.

My speedo did the bounce thing and I took off the speed sensor and cleaned it up and it worked great... for a while. then the irratic shifting, bucking... came back. I went to a junkyard and got a used speed sensor and haven't had a problem since. Good luck.

 

Thanks man, I'll definitely try that...going to go to the wrecker on tomorrow or tuesday. I'll let you know how it works out. Cheers,