Loosing revs while lights are on? eg civic d15b4

[4age8u]

Hey guys just abit of advice needed..Car runs fine but when i turn my lights on revs drop to about 100rpm like about to stall? but never does..

what should i check..

Alternator has been reconditioned lately..

can it be the battery or anything else..went down to my local supercheap and they have this battery tester thing..they said the battery was sweet but meh i dont belive them they no nothing:thumbdwn: so before i buy a new battery what else can it be

thanks for your help guys!

[geeang]

Check all of your grounds as well, just to be on the safe side before you go spending more money on a new battery.

[4age8u]

yeap will do now thanks mate

[JohnL]

IACV probably isn't working, and / or your base idle speed is probably too low.

[OMG.JAI xD]

IACV probably isn't working, and / or your base idle speed is probably too low.
^^
As above. d15b4 is..carby?

Your initial idle might be too low, and any extra load cant be compensated for.
Try raising the idle a little bit.

[4age8u]

so raise the idle abit? im getting a new battery tommorow

[bennjamin]

dont see how the battery is relevant to idle at all. I think perhaps loose ground/s or faulty new alternator

[OMG.JAI xD]

When your car is running the battery has no function besides taking charge from the alternator and giving a safe flow of electricity for components.

Your electricals are all being ran by the alternator when the car is running.
The battery is only used to start the car (being very general). After that its only holding or maintaining charge from the alternator.

Why buy a battery when a tester specifically said you dont need one.
It wont fix the problem.

[4age8u]

well battery has indicator built in it...its black meaning no charge..what mechanics have told me is that my battery is very low and when i turn my lights on i just loose revs and the alternator is getting used to much,meaning more wear..

[4age8u]

When your car is running the battery has no function besides taking charge from the alternator and giving a safe flow of electricity for components.

Your electricals are all being ran by the alternator when the car is running.
The battery is only used to start the car (being very general). After that its only holding or maintaining charge from the alternator.

Why buy a battery when a tester specifically said you dont need one.
It wont fix the problem.

tester test the battery when the engine is on oviously power is all divided around the alternator/battey/wires so its all even..so your saying lights,hazards,subs,speakers,guage lights,brake lights etc can run with barely using no batter at all? thanks

[4age8u]

So im getting 2 different answers here lol guys please lol do i need a new battery or not mechanics think yes..ground all fine..alternator has been rebuild 3months ago..

[OMG.JAI xD]

If your battery is not holding charge due to a badcell, then ok you have a problem, itll decrease your charge rate.

I dont understand why you would do a battery test while the car is running. Thatll be an alternator charge test.

That black marker doesnt mean no charge. It means insufficient charge and you need to recharge the battery. And you need to do it by charging externally with a battery charger.
Low intial battery charge wont effect anything when the car is running UNLESS as ive said above you have a bad cell in the battery.
You can have a new battery that has been discharged just enough to start the car and it wont effect the charge rate. If anything itll raise the charge rate.

And you have to remember. An alternator isnt designed to cope with JUST that much load.
Lets say you have an 80 amp rating alternator. During normal driving youre proably only using 40-50amps.

[OMG.JAI xD]

So im getting 2 different answers here lol guys please lol do i need a new battery or not mechanics think yes..ground all fine..alternator has been rebuild 3months ago..

I recommend you get a proper battery test that actually tests the battery.
I know dealers have battery testers that show you the condition and state of charge of the battery. Or have the car running. Put a volt meter across the battery terminals. Jot down the charge voltage, see if it spikes. Turn your headlights on and youll probably see it drop one moment and pick up the next second. It wont be the same as the charge rate without the lights on. But it should be close to it.

If you still opt for changing the battery go ahead.
If it fixes your problem good on ya, I hope i wasnt misleading in any way.
But if it didnt. Well what can I say.

[4age8u]

If your battery is not holding charge due to a badcell, then ok you have a problem, itll decrease your charge rate.

I dont understand why you would do a battery test while the car is running. Thatll be an alternator charge test.

That black marker doesnt mean no charge. It means insufficient charge and you need to recharge the battery. And you need to do it by charging externally with a battery charger.
Low intial battery charge wont effect anything when the car is running UNLESS as ive said above you have a bad cell in the battery.
You can have a new battery that has been discharged just enough to start the car and it wont effect the charge rate. If anything itll raise the charge rate.

And you have to remember. An alternator isnt designed to cope with JUST that much load.
Lets say you have an 80 amp rating alternator. During normal driving youre proably only using 40-50amps.



first of thanks for your help mate appricitate it Plus rep!
How do you know if my battery has a badcell?
So you think i need a new battery or try charging it..
battery water is full..car starts first time,once i start using lights,cd,speakers fog lights,Revs drop bad...

and when i give it abit of throttle headlights get brighter..then back to low idle and headlights arent so bright untill i start moving again

[4age8u]

I recommend you get a proper battery test that actually tests the battery.
I know dealers have battery testers that show you the condition and state of charge of the battery. Or have the car running. Put a volt meter across the battery terminals. Jot down the charge voltage, see if it spikes. Turn your headlights on and youll probably see it drop one moment and pick up the next second. It wont be the same as the charge rate without the lights on. But it should be close to it.

If you still opt for changing the battery go ahead.
If it fixes your problem good on ya, I hope i wasnt misleading in any way.
But if it didnt. Well what can I say.

yeah thanks mate got me scard for a second

[OMG.JAI xD]

If your car starts first time everytime you wont have a badcell.
A badcell wont hold charge. Its like having an open circuit connection.

I still dont think you need a new battery.
Only reason is because you say your car starts with no problems.

As pervious posts. Try raising the idle a touch. Use a tacho (a multimeter with rpm function) and adjust your idle mixture.

Turn your loads on and see if its still doing the same thing (load being all the electricals).

Being carby fuel delivery isnt controlled by an ecu. So its very hard for it to cope when you have stationary load. (ie, a/c, lights, sound system etc)

[4age8u]

okay guys update,today i went to repco and battery world where they get there machines and check your battery condition they both said battery was absolutly fine!

any ideas to check?
Grounds are all fine..
were going to adjust the idle on the weekend..

anything else to check? thanks

[JohnL]

As I said earlier, check the IACV function.

[OMG.JAI xD]

Come back to us when you bring up the idle a touch. Make sure you guys know what youre doing.

On a carby its very rarely electrical components effect idle (to a certain extent, disregarding sparks n timing).
Everything is mechanical with the exception of some systems.

[4age8u]

ok thanks does a timing belt have to do with any of these,mines about 5000ks overdue..getting done next month

[altong0840]

i got the same problem too, i just done my timing and serviced, i dun think it is the problem~the rev drop no matter what electic stuff u turn on, even the fan~ still dunno what can i do with it

[JohnL]

does a timing belt have to do with any of these,

No.


mines about 5000ks overdue..getting done next month

Keep the rpm down in the meantime...

[4age8u]

thanks guys

[4age8u]

update my newly reconditioned alternator just shat itself yesterday and the car i now back at the mechanics getting fixed under warranty