what does and ECU do and where is it?

[HondaManDan]

yeah.. i've been hearing a lot about this.... what exactly is the ecu? what does it do? and where is it in an 88LX sedan? thanks!

[Chrome_thangs]

All 86-89 honda accords have a box under the driver seat, this is your ECU. Your ecu senses when something on your car is not working (sensor, switches, etc.) I also think it controls your fuel injection (if u had it) and a couple other things.
You can check your ecu by pulling your driver seat foward and looking behind/under the seat and opening the little plastic door. Your key needs to be in the ignition w/ it turned until the dash lights up for the ecu to respond. Go check and count the number of blinks, if any, you have and look in the FAQ section for the meaning.:smokin:

[CoAsTeR]

??? I thought that was the 'black box' for my car.... kinda like the 'black box' flight recorder in airplanes.....

[Sabz5150]

The ECU in a fuel injected 3g controls the engine. Without it, the car won't start.

-5150

[pimp86LX]

sof or us 86 carb'd guys it just collects sensor info? does it actually control anything?

[Sabz5150]

Yes, on the fuel injected 3g's it controls the injector firing, fuel maps and all the other goodies that make the car go vroom.

-5150

[dj99]

ECU stands for "emission control unit" and controls basic i/o functions of your engine. It gets the signals from your various temperature and O2 sensor(s), and tells them all what to do based on the info. If the sensors are broken, it tells you via the blink codes. It controls the efficiency of your engine.

[POS carb]

it's 'engine control unit'... it is necessary on the efi cars and if left in stock form it it necessary for the carbed car. its function is to take in a multitude of inputs from sensors and using these inputs it compensated for varying conditions, altitude, speed, throttle position, oxygen content in exhaust etc all to get a good clean burn in the motor. an efi ecu controls the duration of when and how long the injectors are open, the carb one is there mainly to control all the little solenoids and gadgets honda stuck in there to make the carb car emmissions friendly with a carb.

fuel injection doesn't require an ecu, some cars like old porsches and corvettes were available with mechanical fuel injection, but it wasn't anywhere near as precise as ecu-regulated fuel injection

modern ecu's make hundreds of adjustments per second, control engine ignition, fuel mixture, even the automatic transmission to the point of 'learning' your driving habits. it controls the charging and boosting cycles of hybrid cars, etc. efi systems are so advanced now that many cars don't even need a return line in the fuel system, the fuel delivery is EXACT.

[RedneckRicer]

whats the difference in an Auto ECU and a 5speed ECU? because my car runs fine still... haven't had it on the road but it fires up and moves

[smufguy]

there is literaly nothing to it. yeah the wiring harness are different, and the shape and the position of certain sensors are different, but the function is the same. auto or manual, its all the same thing for the ecu. but the thing is, on an auto, the ecu also shifts ur gears, so thats the only thing i can think of that the ecu might or might not do. But u see, in an auto, u see a cable come to the throttle not a wiring going to the ecu. so my guess is, the ecu checks out the Throttle position and decides when to shit also reading input from the tach.