New battery and idle speed

[RoelfleRoux]

Gents,

This morning when I started the car, I thought the starter sounded a touch off beat. In the afternoon there was no doubt that the motor was spinning sluggish to start. I immediately drove to the battery shop to have a new one fitted. On the way there I also noticed that the little green "wheel lights" on the dashboard would dim when the brake lights come on.

The car was without a battery (while the shop fitted the new one - I went for as big as the bay would take) for no more than three minutes. The dimming wheel lights are fixed and the starter attacks the motor with a healthy swing - BUT - the idling is down to about 500rpm.

I think I recall that my 3.5 Blister also did something strange after a failed battery and then sorted itself out after a day or so.

Any opinion from the experts?
Car is going in for the 90 000km service (under maint plan) real soon, so if things don't come right before then, hopefully they will be able to sort it.

Thanks
Roelf

[jotto]

Hi Roelf

The new battery should not affect the idling. The only thing that it could be, related to the new battery, is that the battery AH and load/charge rate is not compatible with the alternator, resulting in the engin having to work harder to maintain the charge., but this is not likely, as the vehicle is supposed to adjust its idling accordingly.

De-couple the battery while idling and see if a differnce in the idling speed is noticed.

Sure would like to hear what the issue was when you find it though.

Cheers,

Johann

[RoelfleRoux]

I'll def. close the loop at some point in the near future.

It isn't a show stopper and if I wasn't so "gauge aware" I most probably wouldn't have noticed. Think I'll give it a day or so before trying anything, but will keep you posted.

[4ePikanini]

DO NOT disconnect the battery while running. Most modern cars will fry the voltage regulator and take a bunch of expensive electronics and ecu boards with it.

It is a common problem with the gen2 v6 engines to have funny idling after a battery swap or battery disconnect.

Give it a few days to sort itself out. More than likely it will.

[Dean Stephens]

The new battery should not affect the idling.

Fitting a new battery will affect the idle speed - The procedure to reset the idle speed is detailed in the owners manual - if you have it. If this does not work (as in my case with my previous 2,0L iO) a 2 second visit to the local agent sorted the problem. If you need a copy of the relevant pages of the owners manual just shout and I will post them here. Changed the battery on my new old 3,2 and the reset procedure went without a hitch.

[4ePikanini]

The new battery should not affect the idling.

Fitting a new battery will affect the idle speed - The procedure to reset the idle speed is detailed in the owners manual - if you have it. If this does not work (as in my case with my previous 2,0L iO) a 2 second visit to the local agent sorted the problem. If you need a copy of the relevant pages of the owners manual just shout and I will post them here. Changed the battery on my new old 3,2 and the reset procedure went without a hitch.

I don't know about the io but the gen2 V6 engines have a stepper motor that electronically controls the idle speed. There is an adjustment screw on the throttle body but in most scenarios that should never be touched from the factory setting.

The 3.2 Di-D pre-common rail and the common rail's idle is fully controlled by the ecu.

[RoelfleRoux]

Yip, fixed itself over night. Running like a dream again today. Thanks for the comments

[4ePikanini]

shhhhhhhhh

don't tell the appliance guys - then the secret is out that pajeros mend themselves!

[4ePajero]

Two things we learned from this thread:

• Mitsubishi ECUs need a day or two to reset, after a battery disconnect.
• NEVER disconnect the battery from a running engine, it will fry the electronics!

[Gemaskerde Tuinvurk]

Good summary / tips!!