I've got a 97 SSEi. I just upgraded the big three, ran a knukonceptz high output alternator and an optima red top to power my Type Xs. I've got them running at one ohm to an Audioque 2200d. I have 0 gauge monster cable run for the big three and my Amp/Cap wiring. My battery voltage started running low about a month before I upgraded everything. It'* only gotten worse. Even with the subs off, the heater off, and everything else, if I'm sitting in drive at a stop light with the brakes on, my voltage drops below 11. If I throw it in neutral it goes up. As soon as I hit the gas everything goes back to normal voltage wise. None of this makes sense to me because I just upgraded all of my wiring and my belt'* good as well. If anyone has any suggestions that would be greatly appreciated. She runs kinda rough, not missing or anything, just seems like a rough idle. The plug wires are new. Im at a loss, someone please help!!!

Sounds like the new alternator couldn't take the pain.

As Venom stated u could have taxed ur Alt... did u run ur amp at 1 ohm for a while before u did the big three? or u didnt ground one of the new big three cables well enough... did u remove all paint from the STEEL surface?

I did the big three before I hooked the amplifier up. It'* a 200 amp alt. I just had it tested at autozone and they said it was fine. Maybe the alternator was faulty in the first place? I have a 250 amp fuse running to the subs. I'll double check the surfaces for the big three. Any other suggestions just in case? Thanks for the input.

it sounds like a grounding issue... check for corrosion also, cables going to fuseblock, battery + and -, ect

I don't see grounding an issue if as he states everything is off and this still occurs at an idle. But but it never hurts to check. Remove the ground shine it up, apply some no ox grease and retighten. If your still getting a voltage loss without anything on, the alternator'* most likely on it'* way out. If you have a voltmeter you can check it yourself. With nothing on it should read 13.6 ish/idle to 14.4 volts reved. Not sure the voltage parameters exactly since it'* a Knukoncepts "custom" build. I checked their site out. Not very confident of their own work if they only give a 6 month warranty.

Thats alot of wattage right there. Any little loose connection or improper ground could take out/or brown the alternator. Possible PCM damage? Doesn't that amp state not to run lower than 2 oms. Thats what I'm reading from several internet reads.

Ill have to check the grounds Friday when I have a day free from work and the wife. That particular amp is fully stable at one ohm. I hope that my PCM isn't bad, its a ZZP. But what can damage the PCM? I guess what'* confusing me so much is that it only does when I'm idling in drive at a stop. I've noticed that when my cars cold the voltage doesn't drop, but as soon as it warms up, it starts acting funny. I'm trying to get a hold of knukonceptz. Hopefully they get back to me tomorrow. Thanks again for the suggestions

PCM an outside chance, not trying to be a doomsayer here, just exporing the things that could get damaged with voltage swings and leave the car running rough. Grounds a first easy thing to check, And I can see it getting "warm" if your pushing that thing hard. If it pulls 200 amps at 2 ohms, I'm sure it sucks every volt it can find at 1.

it runs better when cold because the car will idle higher when cold, rather than warm, same when ur on the gas opposed to sitting idle at a light.. seems ur only getting descent voltage at 1500rpms and higher.

Call me the one to run against the pack, but I will ask about the battery. What is the voltage of the battery with the car off? I wonder if the battery is packing up, and the alternator just can't keep up with the load at idle.