I'm in the process of tracing down an ignition problem that has had me stumped for at least the last year. I've got it narrowed down to either the alternator or distributor. What I am wanting to know is what should my voltage be at wot? I've gone over some logs in the AEM and have noticed that my voltage is dropping from around 13.8v at idle or cruising down to around 12.5v under boost or wot. I've been told that most cars need around 14v to run everthing properly. Any input is appreciated.

 

i honestly dont' have that much experience, but i'll give you my 2 cents. As far as i know, you should be getting about 11-12V without the motor on. Motor on should get 13.5 volts. I haven't really looked at my voltage as i accelerate, but I do know that you should be around 13.5-14volts under throttle. Your voltage will drop a bit if you have a lot of electronics on including stereo, lights etc.

 

sounds to me like your alternator might be slacking off in its old age.

 

I sure hope that's the problem. I am going to be trying a new one tomorow, I'll post up my results.

 

a voltage drop will affect your injectors!

 

Well swapped alternators and no luck. Voltage acted pretty much the same. I did notice when I was driving it that there was about 20degrees of knock retard at times though. I am positive this is just false knock causing this (a/f is perfect) since I've never even messed with the knock settings from the basemap. BTW this has been a problem for a long time just been getting worse lately, which doesn't add up with the false knock idea. But what I don't understand is the knock retard will stay retarded even at idle for a while after running it.

Tomorrows test; unplug knock sensor and keep a close eye on that a/f and see what happens. Wish me luck.

 

you have to setup your knock voltage table. If you positive that your timing is conservative then just disable knock control. It took me a while to realize that it was taking 20deg out on my setup too lol...it was really a dog, definatley fix that

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xenocron &raquo;</TD></TR><TR><TD CLASS="quote">a voltage drop will affect your injectors!</TD></TR></TABLE>

the ems has a voltage compensation table just for that reason


as for the voltage drop. i am noticing this as well.. after we had an alternator crap out on us i started logging voltage and i see it drop under wot conditions. its a consistent drop so im not toooo woried about it.

when we get the other car w/the ems running ill log the voltage on that car and see if its the same on that car as well

 

Well, turns out the problem lied in the distributor. I rigged up a brand new single cam distributor I had laying around and it ran perfect and pulled harder than it has for a long time. Funny thing is it's running on the stock coil and the MSD box isn't even hooked up. Time to hit the track.