As far as I know, when you disconnect the battery, the ECU resets and then it takes a while to re-calibrate. During that time, driving will be a bit rough, especially idle.

[tell me if I'm wrong]

In the last year, whenever I disconnect battery, driving gets so rough that I cannot drive at all during traffic hours. This means that I cannot even step on the break pedal at low speed because the engine always switches off. I can only drive at higher speeds and use the handbreak instead. And all this takes about a week to come back to normal.

I would like to ask. Is this normal? can I do anything about it? any trick to return it to normal faster?

 

You are wrong....you have another problem....the only things that may happen when you disconnect the battery is to loose all your presets in the radio, clock, cels will usually appear and disapear with a couple of starts. It should not effect your ECU in any fashion (unless you short it out).

 

We're going to need some information.
Model year, miles on the engine, maintenance history, any recent changes or mods and anything else you can think of.

 

It would help if we knew what your LT and ST fuel trims are after it runs better

It is possible you have a problem that is being masked by the 20 percent fudge factor the ECU uses

It should run better off a reset than that

 

03 model JDM
60000km (if not reset at import - god knows!)
no mods
no serious maintenance just replaces MAF sensor, O2 front-rear sensors.

This started after a cat was jammed in the engine, destroyed the oild pump and a few wires (maybe something was short at that time) but the mechanic told me it would be rough for a while until the calibration finishes.

I am quite sure that before that, whenever I disconnected battery, it wasn't like that.

It will return to normal, I am sure but it will take several days and right now, you cannot leave the car running idle. you need to step on the pedal all the time.

[dannobre] I am afraid I don't understand you (either my English or my poor technical knowledge)

 

I'd check for vacuum leaks first...
https://www.rx8club.com/attachment.p...1&d=1274140084

Your problem could also be typical maintenance items such as plugs, coils wires, dirty MAF, intakes filter, intake screens

Any other issues? Check engine light?

 

why are you disconnecting the battery?

 

I disconnected the battery now to replace it because it died.

As far as vacuum leaks, maf, etc. If those were the issues, wouldn't they be permanent? would they appear at battery disconnection and be fixed slowly with calibration?

The basis of troubleshooting is that this appears always when memory is lost from battery disconnection and then it recovers after several days.

No other issues, lights dsc off, traction control, gone by resetting using the steering wheel method.

no codes stored

Please tell me what you think

 

The diagnosis was as follows:
There unit that opens/closes the air flow (I don't know the English name but it is translated as batterfly from Greek) was very dirty and wasn't so flexible to move quickly and that's why due to calibration inbalance it couldn't handle it.

The ECU was re-calibrated manually on the diagnostic and now everything is back to normal.

 

Sticky throttle body

strange that an ECU flash helped that

 

Okay, but why was the throttle body so dirty? Oil in the intake?
Did you check the accordion tube between the intake and throttle body for oil?

 

Flash did not do anything....Mechanic just cleaned the throttle body....it's obvious car is not maintained properly.

 

I was trying to be diplomatic

 

I have no idea why. I didn't check anything myself as I didn't have a clue what the problem was. I assume the problem was a aombination of dirty throttle body and the ECU. When the ECU was calibrated I just didn't feel the symptom because it was operating normal. It was just showing when the ecu was reset and couldn't properly operate. That's my assumption.