Hey folks, I have just had to put a new battery in my Alphard after the last one died. Luckily I had a spare which was bigger than the dead one. I noticed that when stopping at junctions etc the idle speed was really low and felt like it was going to cut out. I have since replaced the spare battery for a nice new one and it's doing the same thing. I did my research and purchased what i believe to be the correct one (Yuasa 5005 580a 65ah). With the 1st battery swap the idle issue did go away after a couple of days driving so I am hoping it will again now the new battery is fitted. Anyone know why this is happening? Hopefully it will fix itself again but still curious of the cause.

Try this step

 

 

 

 

 

 

 

 

Modern engine ecu’s constantly monitor the engine and adjust things to ensure maximum efficiency. 
When you change the battery all these things will be lost from the car’s memory and need to be “relearned”. 
This will sort itself out with normal use. 
 

OK, it did seem to sort itself out last time so hopefully it will again. I will try the process in the video although mine is push start it may still work. It seems like a legit reason for doing it. I wanted to be sure it wasn't an engine or ecu issue but that does help, thanks guys 👍

I think just drive it as normal. 
There are other reasons for a low idle but if you’ve just changed the battery that’ll effect things for a bit. 

Hi all,

In case it us of interest/help to any one.

My 2.4 Suffered from a dead battery.  I connected up a substitute to drive a couple of miles home.  although it started ok the idle was very low and sometimes stalling.  I charged up the original  battery, and it was ok, but the idle revs were only about 300rpm.

I installed a new battery (as I was going on a long trip), and still had a low idle.  After some 300miles the idle is fine and back to normal.

One thing I did notice was a short while prior to the dead battery the idle did not seem right.

 

Possibly using a temporary power supply via the obd socket would maintain the ecu memory while the battery is changed.