Technical Interesting problem. has anyone any ideas?

[milko]

2011 500c twinair.
I have two issues
1. Start the car ignition light remains on plus no power steering. turn engine off start again everything is fine all working except dreaded stop/start which has only worked about five times in the 9 months I have had the car. So far I have replaced the battery and alternator. Have Fiat ever done a software update for ecu?
2. Start engine so ignition light remains on ( problem 1 ) when cold the engine runs fine. If the car starts with ignition light off when cold the engine runs ok for 30secs then misses and is very lumpy, also if you touch the throttle it dies and is a real sod to re start. Have replaced multiair unit but the problem remains.
Multiecu is showing no fault codes.. The only message I get is on a very few occasions is start/stop is unavailable. Get the beast running and it won't miss a beat. Done a 100 mile run the other day so I am thinging it's not the new battery. Anyone got any ideas?

 

[Piccolo Nero e Bella]

Have you replaced the earth strap? Seems to be a source of some electrical problems in older (and not so old) cars in your part of the world.

 

[steveras57]

Have you replaced the earth strap? Seems to be a source of some electrical problems in older (and not so old) cars in your part of the world.

Dont assume the battery is good test it! you need 12.4 volts MINIMUM and 12.7/12.8 is better!,Id would also check the car is charging properly!- you need13.2 /14.1 volts on the meter and also check if stays the same if lights and air con switched on, any less than these values and you may have an issue with your"smart" alternator!.