Problems after battery change -2005 MMT

[sceh]

I changed the battery after now it idles at 400rpm and almost cuts out. It drives ok but if I stop even after 200 yards, the MMT box refuses to engage. If I stop the engine and restart it, the gearbox engages and off you go - until the next time you stop.
This is directly related to the battery change since it has happened before after I left the battery disconnected for a day or so but this time I bought a new battery and changed it inside 30 seconds.
Of course this also happens when you are just about to engage a roundabout in front of a big truck...
Why?
Any clues?

[WeeYari]

You need to drive it non-stop for approx 30 minutes while the ECU relearns fuel trims. ECU memory is errased after about 10 minutes of battery disconnect.

If you have to stop vehicle while driving during the relearn phase, just remember to give it a bit of throttle to prevent stalling out.

[toyotavios_11]

When the negative battery terminal is disconnected during inspection or repairs, the ISC learning values are cleared. The ISC learning must be performed by warming up the engine and idling for 5 minutes with the ECT at 75°C (167°F) or more because DTCs cannot be detected with the ISC learning values cleared.

[sceh]

So what a happens when the car is new? Does it have some preset default data? If so, why is this not the default after a battery change and if not, how come this doesn't happen with new cars?
Odd but very annoying! Thanks for your replies - I will do this today

[Brighton]

So what a happens when the car is new? Does it have some preset default data? If so, why is this not the default after a battery change and if not, how come this doesn't happen with new cars?
Odd but very annoying! Thanks for your replies - I will do this today

Some cars just do that while others don't, its a manufacture specific thing. All cars have a preset learn procedure and they'll run closed (?) loop initially while they gather data and learn to run given the data from the cars sensors. Most newer European cars won't even run when you swap the battery if you don't keep the ECU powered during the swap. It's just how it is and when it comes to new cars on dealer lots, this is a well know thing in the auto industry and dealers will not deliver a car that isn't set up and ready to go, so they'll just have someone drive it around the block before handing the car off to the new owner.

[sceh]

Thanks for your informative reply. I warmed up my car and ran it around a bit and it seems to be 'better'.
I do find it odd that all electronic devices use flash memory or equivalent so they don't forget so I am surprised cars don't. There must be a reason so I will dig into it and try and find out why.

[tmontague]

Some cars just do that while others don't, its a manufacture specific thing. All cars have a preset learn procedure and they'll run closed (?) loop initially while they gather data and learn to run given the data from the cars sensors. Most newer European cars won't even run when you swap the battery if you don't keep the ECU powered during the swap. It's just how it is and when it comes to new cars on dealer lots, this is a well know thing in the auto industry and dealers will not deliver a car that isn't set up and ready to go, so they'll just have someone drive it around the block before handing the car off to the new owner.

Coincidentally I have noticed that letting my yaris idle for 20 or so minutes fixes the idle hunt issue from disconnecting the battery- it's possible that manufacturers or dealers let the cars idle for a specific amount of time without touching the throttle

[Brighton]

Coincidentally I have noticed that letting my yaris idle for 20 or so minutes fixes the idle hunt issue from disconnecting the battery- it's possible that manufacturers or dealers let the cars idle for a specific amount of time without touching the throttle

For what it's worth Subaru's do the same thing, there is a little procedure you have after a battery swap. You do a few specific things with the key in the ignition to start the learn procedure but once you start the process, the car will change idle every 10 seconds over the span of 5 minutes until it learns what it wants to do, then it's fine. If you ignore this step and just drive it, it'll idle horribly and randomly for a good few days of daily driving. I would think there is something similar for other manufactures as well.

[tmontague]

For what it's worth Subaru's do the same thing, there is a little procedure you have after a battery swap. You do a few specific things with the key in the ignition to start the learn procedure but once you start the process, the car will change idle every 10 seconds over the span of 5 minutes until it learns what it wants to do, then it's fine. If you ignore this step and just drive it, it'll idle horribly and randomly for a good few days of daily driving. I would think there is something similar for other manufactures as well.

Yup, read about this when I picked up my 2010 Outback. It's an easy process, essentially dont touch the throttle and let it idle for 10 mins plus a few other small things as you mentioned

[sceh]

I wonder if there is such a procedure for Toyota? If so, my garage hasn't heard of it and recommended a full service at vast cost when I mentioned it. Similarly, when I told them the MMT box sometimes disengaged they told me, quick as a flash, that I need a clutch and servo change..

[WeeYari]

I wonder if there is such a procedure for Toyota?
Given the number of these low idle/stalling threads after battery disconnect, and the members we have had who are Toyota techs, I'm sure that if there was a procedure we'd have heard about it by now.