89 Tercel Engine Fuse

[kvnnarv]

Still been trying everything to get my Tercel to drive smoothly. Today I had disconnected the ECU fuse on the driver kick panel. Has been running better since. Also I tried disconnecting the Engine fuse as well. Man what a difference. I had received about 90% of power back. Only sputters slightly on acceleration, but other than that ran great. But in doing so I realized that my radio kept shutting off when I turned the blinker on. I know that means that the alternator is not working. So I plugged the fuse back in and it kicked back on. My question is, What does the Engine fuse control?

This car is driving me nuts with the dang bogging on acceleration and cruise speeds . I've been trying every weekend to disconnect different things to get it to run decently. On start up, whether the engine is cold or hot, it runs great. Then seems like something is switching on and off to cause it to run differently.

I'm running on the lean side. Advance timing to 10 Degrees BTDC. Replaced main jet o rings. Had done engine flushes, now my oil is clean again. Cleaned EGR valve. My Air bleeder valve is disconnected, it will not rev past idle connected. Spark plugs, wires, cap, pcv, fuel filter all changed. Ive replaced the Distributor Vacuum Advance valve and that helped with idle. I've also noticed that if I hold back the cylinder at the top of the carburator when revving the engine it'll rev nicely. I love this car, even though it looks beat up. I'm the second owner from 47k, and now currently has 91k.

[Tercel GTS]

Sounds like a bad body ground. Both engine and car body must have a good ground connection to - side of battery.

[kvnnarv]

I'll take a look. You dont happen to know where the engine ground wire should be do you?

[Tercel GTS]

It will be the fatter one on neg side of battery. Follow it.

[noahthefrog]

The computer on the '89 only does a couple things and the one that will most interfere with engine behavior is the electronic controlled air bleed. The air bleed is opened closed based on what the oxygen sensor is reporting and probably RPM also. If the oxygen sensor is the original -it's the most likely problem.

You can test the oxygen sensor by hooking up a volt meter positive lead to the sensor wire and the negative to the battery negative terminal. The voltage should be between 0 and 1 volts and typically around 0.75v when engine is revving around 2-3000 rpm. You can find more info about the electronic air bleed system in the weber swap guide linked in my signature towards the end. If you want to disable the computer without pulling the fuse, you can just unplug the EBCV or oxygen sensor and the computer will stop adjusting things on-the-fly. Disabling the computer will cost you gas mileage though.

EDIT: forgot to mention the computer expects the engine to be running slightly rich since it can only lean the mix via air bleeds.