Help with stalling idle....

Anyone help/advise?? Left the lights on last week and returned to a flat battery. Rescue org got it going after a 2.5 hr wait but since then the idle speed is steady and OK but when revved it builds as it should but release your foot and it almost dies but then recovers. Driving means it does this as you change down with a fear it will stop. Not sure if the battery stupidity is a coincidence. Not technically minded these days but would welcome any advice as it's bugging me. East Northants area. Cheers

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Originally Posted by gymm

Anyone help/advise?? Left the lights on last week and returned to a flat battery. Rescue org got it going after a 2.5 hr wait but since then the idle speed is steady and OK but when revved it builds as it should but release your foot and it almost dies but then recovers. Driving means it does this as you change down with a fear it will stop. Not sure if the battery stupidity is a coincidence. Not technically minded these days but would welcome any advice as it's bugging me. East Northants area. Cheers

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Before getting too involved: a new battery costs about £50 and it is the easiest way to eliminate it, or confirm it as the trouble. I have had two experiences of faulty batteries actually causing the engine to stop in spite of a fully functioning charging system.

Thx I will investigate. Did you have the stalling idle too?

The battery fault makes sense. Could be your draining it and the fast charge did in one or more weak cells, so either you haven't got the juice to keep the ignition and other engine management electrics happy, and/or the load on the alternator trying to stuff 15 volts into a (now) 10-volt battery is putting a huge load on the engine.

It's most likely because your battery went flat the ECU is now having to relearn the long term fuel trim, so will take a short while, you may also notice a change in fuel consumption until it is fully back to where it was.

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Originally Posted by Steve_M

It's most likely because your battery went flat the ECU is now having to relearn the long term fuel trim, so will take a short while, you may also notice a change in fuel consumption until it is fully back to where it was.

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That's interesting! How does that work?

http://stealth316.com/misc/obdii_fuel_trim.pdf

This describes what im talking about, even thou not specific, as this is OBDII compliance, and Beat is pre-OBDII requirements, but any closed loop system uses a similiar principle.

Steve M and steveninjapan

Thanks for your advice and taking the time to assist. I'll get a new battery asap. I thought it could be relevant. Cheers!

Bought a new battery from Central Auto Supplies (CAS) £45 for a decent one with a 3 yr warranty. Took about 30 mins for the ECU to stabilise the idle and now as it should be so took it out for a long drive..... :)

Thats great! glad you're up and running.