FC_mania

with everything off my battery voltage is at 11.4-11.5v

after start up at idle is goes around 13.3-13.5v(never higher)

cruising 13.0-13.2v

WOT 12.6-12.8v ( worse with headlights on at night and make the car engine want to die out and does die out sometimes)

car has an FD alternator wired up properly

has some added grounding points ( alt body to driver side shock tower , front cover and manifold to passenger shock tower , firewall to UIM , firewall to center housing)

the grounding doesnt seem to help my problem

using Everstart walmart batteries.

Anyone pls comment on my problem as i am really troubled by this because i cant tune the car with this problem. Car just has a cd player with the stock speakers but rear ones has been taken out at the moment and the cd player was never switched on when all this happen. car has no a/c , heater etc .....

Icemark

You have a bad cell in the battery and a bad alternator. The bad cell in tha battery might have contributied to the alts internal regulator failing.

Battery should be 12.6 volts at sitting.

FC_mania

but i have change this battery twice....its still giving me the same problem. why is that?

Icemark

are you checking voltage at the battery? with a multi-meter?

FC_mania

yes i am.... whats the normal voltage for car at idle , cruise and WOT? and when car is off?

FC_mania

went to autozone and got it tested today

tested the battery they say its ok .....

then the did 2 load test to see hows the alternator , revved it up to 2000 its ok then let it drop back to idle the engine dies.

the person there told me that my alternator is giving out 0v on the load test , anyone know what my problem is?

Icemark

Battery should be at 12.6 volts when disconnected or the key is off.
Voltage should be 14.4 volts when the engine is running (either at idle, 2K or 7k RPM).

Voltage should never ever drop under 13.5 volts with the engine running.

Icemark

Autozone is completely clueless when it comes to anything eletrical on cars.

12 volt car batteries are made of six 2.1 volt cells and are really 12.6 volts. If the (fully charged) battery is at 11.5 volts one cell is bad. If the battery is at 10.4 volts two cells are bad. Most cars can still be started until about 8 volts, but the battery will not hold much of a charge.

Testing an alternator at 2k rpm is one of the stupiedest things I have ever heard of. You need to know the voltage at idle speed. Anything above idle who cares. You don't sit at a light with the engine running at 2k RPM. Anyway... at idle if the alt is putting out 0, it means that the alt is dead.

FC_mania

i would like to go get a second opinion , which other auto shop is good to test electrical gremlins?

WAYNE88N/A

Therein lies one problem- The alt's normal current path is through the engine housings. That's why Mazda put that rear rotor housing ground right there, close to the alt.

With the car running, the alt is the defacto ground, not the batt negative post. This won't make any sense to you if you aren't an electrician, but extra grounds DO NOT help if your OEM wiring is good (if it's not, fix it). If anything, extra grounds hurt...

Your extra ground wire from the alt to the chassis circumvents the normal path (I'm surprised you didn't notice some performance problems with this). Take the extra grounds off, repair or clean up the existing OEM grounds, and check the resistance of the alt body to rear housing for continuity- should be less than a couple of ohms (you can also perform a voltage drop test between the same two points with the car running- should be .1v or less).

Check your main ground wire down near the starter, clean it up if necessary, and check your tranny-to-firewall jumper...

Check your alt's mounting hardware and metal-to-metal contact points with the water pump housing.

With the engine running, a voltmeter placed on the battery terminals should yield at least 13.6v (that's bare minimum, book says 14v). If not, repair/ clean up your wiring. OEM wiring, that is

FC_mania

hmmm new updates

i swap in a new battery from walmart



when everything is off battery reads 12.63v , microtech handset reads 11.95v

when idling , battery reads 13.98v , microtech handset reads 13.30

at the alternator it reads 14.33v when multimeter is put to check directly on it

what's the prob now?

WAYNE88N/A

The numbers look good- what's the problem?

FC_mania

wayne88N/A : so u are recommending i take off the alternator to shock tower grounding? i read some thread in the forum that says it helps? yea i just dont understand what u mean the grounding was through the engine housing? is there suppose to be any wire there? or how can i check ? what about other groundings from manifold to body , or UIM to firewall?

thanks a lot

WAYNE88N/A

If the tranny to firewall ground (bonding wire, actually) is still there and looks good, remove that alt ground, it can't possibly help.

Have you checked the rear rotor housing ground under the UIM? That's your ECU's ground, one of the most important on the car. No amount of "extra" grounds are going to help if that ground is in sad shape (corrosion under the terminal there is a problem).

I don't have time to go into quantum electrical theory here, just imagine for a moment that all electrical power for your car comes from the negative battery terminal and the alternator body (when running). From this "vantage" point you can start to see why Mazda wired the car the way they did- and that any extra wiring from the block to the chassis only duplicates circuits that power flows through- and that "confuses" components that depend on very precise voltages to operate (namely the ECU).

I've written a large amount of info on this subject- a search will yield more of my ramblings

The ONLY way an added ground ever helps is if the OEM grounds are shot- and that means you need to fix them...

FC_mania

ok but the thing is i no longer run the stock ecu but am running microtech which is a separate harness. do i still need to remove that ground from the shock tower to the alternator body and other misc grounding points?

thanks for the tips

btw the tranny to the firewall wire is broken and is disconnected.

Mark'sMazda

Figure It Out Your Self Veilside!