I have some questions regardig the ECU. I've been getting my codes out on the CEL and have been clearing them with the second clockwise rotation of the ECU screw. But is this the same as resetting the ECU?

I'm also wondering if the ECU slowly adapts to changes in the engine sensors etc. I've read somewhere that after a KS replacement the ECU takes a couple of days to fully optimize the ignition timing, is this true of other sensor changes?

If there is an ECU reset (as opposed to clearing codes) does this speed up the optimization?

 

same thing clearing the codes is basicly resetting your ECU.. or you can disconnect the battery for 15 minutes

 

Turning back the screw and erasing the codes is the same resetting the ecu.

I dont think it speeds it up, but I imagine the code wouldnt come back if the problem is actually solved.

 

Disconnect the battery for 24 hours...imo... that truely clears the codes.

 

Same thing.

 

Taken from the Haynes shop manual.

Clearing codes
After faults have been repaired, the codes can be cleared from the PCM memory. Clear the codes using an OBD-II SCAN tool under the menu for "CLEARING CODES" or follow the process using the screw on the side.
Caution: Do not disconnect the battery from the vehicle to clear the codes. This will erase stored operating parameters from the memory and cause the engine to run rough for a period of time while the computer relearns the information.

There is a differance between clearing codes and resetting the ECU. Personally I'd never want to actually have the ECU reset (run default settings) as it's constantly learning as you drive and will adapt to mods or changes instantly.

 

This has been talked about a lot. You shouldn't remove the battery to reset your ECU. There are steps to reset your ECU for a reason on manuals like ^ he said.

 

I need a little clarification: After a major repair or major part replacement - I have read that the ECU/ECM should be reset so that it goes into a learning mode and makes adjustments to the new part and current drive abilities. Is this true and is this the same as clearing codes with a scan tool. and 2nd part to my question; If you change a major part in the vehicle and do not reset the ECU and codes come up, is it possible that resetting the ECU could fix that problem? Please post reply!!

 

The majority of the time, if not all, just driving it up to 50 miles or more, the new parts working properly cycles through.

The ECU is always looking at the current values of all the sensors. Resetting talk is devoid of understand of what really happens. The ecu is hard programmed to watch for sensor readings within a certain window of values and kicks when the values step out of range. A constant process. If something was replaced/fixed properly, the codes should go away. If they persist, possibly the fix was defective, or a problem with wiring or connections may also need addressing. Some codes are secondary to other problems as well, and the code for that isn't available or didn't trigger. That you'll have to do some searching to eventually stumble on a similar experience documented by others. Hopefully!

Hope this helps!