Ok, was driving home from the movies (say LotR:Two Towers, ******* awesome movie) and i was bumping, just cuz i like to show off when i'm not in little hick towns https://www.nopistons.com/forums/pub...IR#>/smile.png and i noticed my lights were dimming quite a bit, but since i am running 2 amps, fog lights and alot of other **** i didn't think anything of it, until i was driving home tonight, and was watching the voltage gauge, it was dropping 2 volts every time i hit, it has NEVER done this be4 the worst it's been be4 was running at 13.5 volts...i dunno what's going on, i accidentally brushed some wires on the side of the car as i was getting out and saw a blue spark......maybe i am grounding out on the body of the car somewhere?? i dunno, but i am not happy :(

Another reason not to buy stereo equipment beyond good speakers/head units. Well ya ur gonna kill that **** pretty easliy with what you've got. Get the whole alternator rebuilt by a good shop, not autozone etc. They only rebuild the broken part.

upgrade the Alt. run a straight wire from your + alt to your + battery. and i would really take the time to remove the two wires from your + alt. rip them out the wiring harness and run them across straight to the fuse box on the strut tower and the connector that takes it back to the fuse box in the car. You eliminate about 7 feet of wire.

Man, your car sounds like a rat's nest of wiring. You saw sparks meaning you have exposed power wires hanging out near bare metal? Before you buy more parts, I would take the time to check and maybe reinstall safely all of your aftermarket lighting and audio stuff. Make sure all your wires are of proper guage, with proper connectors, fuses, wrapping/tubing, etc. Check your grounds, just do it the right way.



I had an electrical fire in my first car 11 years ago due to my half ass amp install. I didn't know **** so I ran the puny 12 guage radio shack power wire under the seat, on top of the carpet, basically right in line with the seat track.... moved the seat, wire grounded and burned because of no fuse, filled the car with burnt carpet smoke and burnt the **** out of my hand yanking out this wire just to save my car. It sucks to lose your audio equipment over a bad install or even worse, mess up your car's electrical system.

I have 2 gauge wire ran with 100 amp fuses after the battery and be4 the amp, alos fuses on ground....i was carrying an eq in to the house one of the wires off of it touched the bottom ot the door sill and i coulda swore i saw a spark, i haven't got my battery tie downs, i went to a way bigger battery and it is a universal, both top and side post and i lost the things that go over the side posts, so i think it may be grounding out on those....

this whole thing scares me

Try taking a test light to the body of the car if you think there is currant running thru it.

a decent Cap will help some with the dimming, and maybe save you from killing your alternator again, not to mention it will keep the sound quality from dropping on your subs.

well i tried the test light on the body and didn't get anything, musta been residual electricity on the crossover...i found out if i don't turn on my subs right as i start the car, let it run for a bit and charge then turn em on it's not as bad, it still drops it about a volt but not to dangerous levels (under 12)...my g-friend is gonna get me a cap for my b-day if i don't get it be4 then, will a 1/2 farad cap be enuff? thanx ppl...

A half farad should be fine for your system. I doubt your Pyramid amp is putting out a real 800 clean watts anyway. If the cap doesn't help the voltage drop, then you will probably have to get a higher amp alt.



Where did you run this 2 guage wire to the amp? That is friggin huge.

there was a system installed be4 i got it, it was ran thru the boot for the clutch cable i believe, it was a rubber boot i know, i cut the **** outta my hands getting it thru....it runs along side the driver's seat under the carpet to the deck....i forgot to mention on everything but the amps, i am grounded on the battery i was told this is the best way to run...i.e. my fog lights and other lights are connected to both the + and - posts on my battery, my amps are grounded on the hatch latch...they are grounded with 8 gauge wire....

There is no need to ground your audio system on the battery. I'm not sure why so many people think that is necessary. For amps especially, the shorter the ground the better (I know you said your amps are grounded to the hatch latch). You should ground the amps right to the chassis less than 8 inches long if possible. If you do this, I bet your amps will run cooler with more power. As for the other stuff, try grounding that to the chassis also and not on the battery. It may even help your voltage drop since most of your car's electrical stuff is sharing the battery ground the way you have it hooked up.

thanx FC, gonna go out and do that in just a sec...any good grounding points in the engine bay BTW?? that's y i ended up using the - post...didn't want to take off any bolts to ground...

Actually you want to ground the amps to the battery.. RX-7's FC and FD are renound for having shity ground problems due to the bad ass non rusting metal mazda used in the cars.. also grounding the amps to the battery will give you a better sound quality... copper conducts electricity way better than steel... The larger wire you use the less resistance, so you sould run a 4 guage from the - batt teminal to near the amps then use a ground block and run the short 8 guage wires in to that block.



What you need to do is run anouther ground wire directly from the - batt terminal to the altenator mounting bracket so the altenator has a good ground directly to the battery.. You may also want to run a 4 guage wire from the alt + votage out post to the + on the battery.. you should also clean the posts on your battery and terminals then go around the car and pull off all the grounds and clean them up with a wire brush.. It just sounds like your having ground issues and the altenator is still probably good..



The ground points will oxidize over time so you should do this once a year or so to keep the charging system working at it peak ability.

I understand what you are saying about copper conducting electricity better but it's always been my understanding that the battery, alternator, engine, and everything electrical ends up grounding to the car since the chassis is obviously the largest solid metal ground. I don't understand how there is an advantage of running all these things through the battery post. Don't they end up grounding back to the car anyway? Maybe I'm way off here, I just was always told the shorter and thicker the grounds the better. When diagnosing amp problems, I usually found a sound improvement from changing to a thick and short chassis ground.

LOL....take out the system and you'll be faster https://www.nopistons.com/forums/pub...#>/biggrin.png







just my 2 cents

I see a few problems here...

You should be runnng a ground wire (from the amps) that is the same size as the largest power wire going to the amp. In this case you are kind of screwed because that would be a 2 ga wire, and that won't hook up to your amp. So if you are running 2 ga back to a distribution block, then to 8 ga to the amps, run the same as a ground; 8 ga into a distribution block to 2 ga.

It does not sound like you have a good grounding point. I like to find a good place close to the amps (make sure it's not right above the gas tank, ect.), grind away any paint (get down to bare metal), drill a hole, tap it, then hit the bolt on wire wheel so it is nice and shiny and use that to hold the ground wire to the metal. Also it is recomended to have your grouund within 18" of the amp, the shorter the better. Like Dragon said, RX-7's FC and FD are renound for having shity ground problems.. so it wouldn't hurt running a ground wire from where the ground wire is bolted to the chasis up to the - terminal of the battery. Also run a couple of big grounds from the - battery terminal to the engine then to the chasis and one from the terminal to the chasis.

Also, I think I read that you have a fuse/distribution block in your ground wire, that is useless, get rid of it. If anything it is hampering your grounding because the current has somewhat of a bottle-neck at the fuse.

Getting a cap would help you out too.

I used to work for a car audio store, and did installs on the side for over 5 years. I've had a car take 9th in it's class in a stereo competition (maybe I'll scan some pics of it and post them), also I had a truck that could hit 148 db, and then it broke the RTA.

Yeah, what cabrio said, only thing I would add is to use a star washer and/or nut and bolt.

I figured that was a given, but maybe I should have added that it.





Me too! :stickpoke: