1993 Toyota 2wd 5-speed 160,000+ miles.


I recently noticed that my upper alternator bracket (from the motor) was broke and the lower tab on the alternator was oval-ed out. A friend of mine gave me an alternator and bracket off of a 1991 truck and we put it onto mine. Then I found out the plug on the back of the alternator was different, so we spliced the plug from the '91 onto my '93 harness.

We started the truck, let it idle and it was charging so we thought everything was fine. I go to leave my friends house and as I accelerate the truck starts to stumble and bog down and the check engine light came on. I pulled back up to his house and it smells like it is running rich. So we put my original alternator and plug back on my truck with no change in performance. It will run fine idling and wide open but stumbles at approximately 1000-1500 rpms. (guessing because I do not have a tach)

The next day, with the help of some other friends we try to troubleshoot it. We replace the plugs, plug wires and coil/igniter because the plugs were saturated with gas. Gaped the plugs at 32. No change.

I drive it to a local mechanic to try and find out what threw the CE light and he tells me that my diagnostic port is fried and he can't get a code off it. I really don't trust him.

As I drive back to my friends shop it starts to smell horrible and the floorboard is extremely hot. So we assume the cat is clogged and cut it off with no change. Except for now sounding like a dirt track car.

Next we replaced the O2 sensor still no change.

We removed and cleaned the air filter and Mass Air Flow sensor. It will run slightly better with the Mass Air Flow sensor unhooked, so we replaced it with one from a running truck with no change again. I did however notice that the center pin on the plug is corroded so we tried to clean it as best we could. Still no change.




Anyone have any ideas? Could I have fried something by putting a '91 alternator on a '93? Or could it be something simple that's unrelated? I feel like we are chasing our tails on this one. The truck is 100 miles away from me right now so I won't be able to do much until this weekend.