I replaced the alternator with a brand new FD alternator for my s4 na body. I ran a new 12v constant as well. When I start my car I still have to rev it over 2500 rpms or the alternator doesn't 'activate'. Then when it activates at idle (1k rpms) im making 14.9 volts per haltech data page. I have my afrs set to ~12.5 at idle. When I turn my headlights on, the voltage drops just alittle bit to maybe 14.7v but my afrs go to ~13 at idle. When I turn on the rear defroster and the heater fan on max the voltage drops to 14.2v the afrs go to 14's then 15's then I turn them off before the car dies.

I've gone into the fuel battery correction and tried to adjust it. But it's not specific enough to fine tune the fuel for the different voltages. It goes from like 14.45v to 14.97v and below that 13.94. So there is no way for me to adjust it other than run like 11.0 afr at idle. Anyone else having this issue?

 

I just went back outside and did some more adjusting. I raised the idle a bit more to 1100rpms, then adjusted the afrs to 12.5 with no electronics on other than laptop. I have the fuel battery correction at 0 for 14.97v. When I turn on the headlights the voltage drops to ~14.7 and the afrs go to about ~12.8. I have the 14.45v correction at .22 and when I turn on the heater on max the voltage drops to 14.5v and with this correction I'm getting a 12.5afr. Then the 13.94v I have set to about .44 and when I turn on the rear defroster the afrs just start to go way up, the laptop shuts off and when I turn off the defroster it idles great again... I guess I just need to up the correction on the 13.94v map but it just looks too extreme to be correct.

 

Is there a problem with the engine running with all these voltage fluctuations?

Or are you just **** about hitting a specific AFR with your wideband?

If there are no issues with the engine running, I think you're going overboard trying to hit a specific AFR number...


-Ted

 

This is an NA car? what kind of intake are you running? what porting? is it heavily ported? Do you get lots of vaccum/idle fluctiations? You might want to try the zero throttle map.

 

14.9 volts is on the high side. I bet the plug that goes into the top of your alternator is coroded. I had the same problem, swichted out the alternater to a known good, still had the same problem. Cut the plug off and replaced with female spade terminals. Problem gone....

 

Yep!
Common Mazda problem especially the fd's with the scoot hoods.

 

I've messed with the battery correction map alot more and it's doing alot better. staying around 12.5 afr. At idle with all electronics off it will stay at about 15v if I turn everything on then I get 12.9v at idle. I am kind of **** about it, but its more like I'm just annoyed and want to fix it. I'll replace that ring connector on the alternator and see if that helps any.

 

Its not the ring connector, how many times do people need to tell you what the problem is.

 

One last question...

DOES THE ENGINE SOUND CHANGE WITH THE VOLTAGE CHANGES?

If not, you're fricken' wasting your time.


-Ted

 

Which connector are you talking about then? There are only two connections on the alternator, the ring connector and the 12v constant which I've already redone.
It did change before I messed with the fuel battery correction map. It doesn't do it now. Since it doesn't do it now I'm not really too worried about it. Only thing that irks me now is that with everything on I'm only getting 12.9v at idle. But oh well.

 

If you used female spade connectors like I mentioned in my post, did you connect them backwards?

clean the battery terminals.

Have a multimeter which can test resistence, test the resistence between the alt refrence wire and the alt ring terminal with the ign on but not running.

Next, test the votage at the alt refrence and compare to the ring terminal or possitive battery cable.

 

Can't you reload the default map settings for just the battery voltage correction?


-Ted

 

As far as I know you cannot reload just the battery voltage correction. But all that does is correct the fuel going into the engine. As of right now the afrs are staying where they need to be. The idle does drop 100rpms when I have an electrical load to 1000rpms. But I have quiet exhaust so having a 1000rpm idle isn't that bad. It also doesn't help any that I'm using an under drive pulley just for the simple fact that it has the correct timing marks on it.