I took my KIA Venga to my local KIA dealers today to complain that the ISG was not performing correctly. The problem was not the usual one that the engine was failing to stop when it should – quite the opposite, intermittently it would fail to start when the ISG had stopped the engine and I depressed the clutch.
The service manager was most attentive and we spent 40 minutes doing laps around their large site to test it out. I am sure you know what is coming – the ISG stopped the engine every time and started every time upon either depressing the clutch or operating the brake a second time. Hence he was not able to see the problem
He went through their standard ISG test procedure which included air con settings, rolling down a ramp with ISG operating to ensure the engine automatically started at 3 mph and stopping the car with ISG operating and measuring how long it took for the engine to start automatically. My car passed all the tests – as it would – because the vexing problem is intermittent.
The 40 minutes was well spent however – because I learned a bit more about ISG and the AGM battery.
ISG operation depends on various pre-requisites including the battery condition - no doors, boot or bonnet open - occupied seat belts buckled, car at standstill with foot off clutch (For manual cars gears in neutral), air con not running at maximum, no significant load on the electrics drawing power (eg : car Fridge in boot), etc. I can’t remember them all.
He roughly gauged the condition of the battery by the simple test of timing how long it took for the engine to start automatically after sitting at a standstill with ISG on. The longer this takes – the better the condition of the battery. My car took more than 2 minutes which indicated the battery was fine – had it have taken only 10 seconds then the battery would be the chief suspect. The longer the time the better the condition of the battery.
He was horrified to learn that I had twice recharged my battery in the car without disconnecting the terminals – even though I had used a proper AGM battery charger. He told me that the KIA instructions to dealers are clear.
• You must first remove both battery terminals,
• Connect the proper AGM charger
• Charge the battery for at least 24 hours.
• Remove charger and reconnect the battery terminals.
• Leave the car for 4 hours for the AGM control module to learn and teach the ECU the new battery condition.
• Start engine and test the ISG.
• Put back your radio setting etc
The AGM control module is inside a black box to the side of the positive battery terminal. It measures battery condition and current flow to and from the battery, constantly communicating with the ECU to control the ISG. I am told that this is a very sensitive unit, costs the thick end of £500 to replace and can be damaged by improper battery charging. Jump starting and battery charging without disconnecting the car terminals or the use of a proper AGM charger are an absolute no-no. If the AGM Module is found damaged – it is generally because an owner has recharged the battery
