TTrx7Pete

Car: 1997 240SX SE with S14SR20DET

Mods:
APEXi Power FC D-Jetro
FMIC
Walbro Pump
Optima Red Top Battery Relocated to Trunk
Profec B Spec II
Intake
3" full exhaust
FAL Electric Fans using FAL thermostat and switch

Background:
This is a completely new problem for my car. As of yesterday, the car decided that it was not going to keep itself running. I couldn't idle and would only get about 12V from the car while running. I know I should be at 13~14V while running. So, I go and get a new battery because this one won't jump. I replace with a brand new Optima Red Top. It cranks right up. I let the car sit overnight and now I'm at 6V.

So I searched on Zilvia for possible reasons: Bad Alternator, Grounds, Open Circuit.

I checked the grounds and they all seem great. I looked for frayed wires, none. I also looked for any blown fuses. None. The battery is relocated to the trunk with the positive wire running up to the front of the car and is attached to the original positive terminal. The ground is attached to the chassis in the trunk.

I pulled my radio out to find that it can run without the ground wire grounded while the radio is inserted into the dash. With the radio out of the dash, the radio will not operate. So I removed the radio.

I still experience voltage drain while the car is off.

I checked the alternator's wires. Ground was good, positive was good, and the snap in connection was tight.

I'm running out of ideas. I don't know if it is a bad alternator or an open circuit. I can't find any conclusive evidence of either.

Thanks in advance.

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia

s13silvia123

loose ground somewhere

__________________
18g and 20g turbo users click on me
http://zilvia.net/f/tech-talk/261219-18g-20g-turbo-users.html

slider2828

Start pulling fuses and test for load changes... Super easy.... One probe on ground and one on positive, pull fuses and look for change....

__________________
Turn and Burn!

TTrx7Pete

I imagine I do this while the car is keyed on, not running and check each fuse for a voltage drop or change? What am I exactly looking for? If I do find a drop across the fuse, what next?

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia

TTrx7Pete

Someone please explain where I am measuring voltage at.

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia

godsmack

did you check the volts coming out of the alternater while car is running?

HPKMotorsports3

sounds like you got a grounding issue...tell me this when you turn your car on does your alt charge the battery back up cause that could also be part of the prob...

datboibrad

total voltage drop. normally if the car dies while driving thats an instant sign of two things. bad alternator not putting out current to the battery OR something interupting the flow such as a blown batt/alt fuse.

as far as the drain the easy thing would be to double check anything you have on the car that has a tap onto the ignition side of the key. i/e gauges controllers etc. one of them is pulling a load even with the key off. could be a situation of mixing the constant 12v and the ign source on said item.

that radio thing sounds kinda silly. they are normally grounded through the dash harness and in some cases if seen people having to splice the ign and 12v wires together just to get the thing to come on.

also if you have a turbo timer id check the ignition harness splice they give you. i had a POS greddy one melt causing the car to constantly blow the 75amp alt fuses causes my car to die similar to what your exp.

acesxx

make sure that the wire that goes from your harness to the alternator is all the way plugged in into the alty... had similar problem happened to me about a month ago!

TTrx7Pete

The wires at my alternator are snug and tight. The connector is in there good too. After checking for open circuits I found my change in resistance. The resistance went UP at the ALT S fuse in the engine block. So every other fuse was reading .884 and then when I pulled the ALT S fuse it went up to .914. It was the ONLY fuse that had a change in it in the entire car. Bad alternator?

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia

slider2828

Here is a guide for everyone who has a battery drain problem: This is only a guide.....


On the battery draining, there is something that is draining the current even though you don't know anything as being turned on. The best way to find what is causing the drainin is to obtain a volt-ohm meter at an electronics store or an auto parts store, or borrow one from a friend. You should be able to get one for under $20. Then you disconnect the clamp from the "-" or "neg" post of the battery, then remove the "+" or "pos" clamp. Then put the two test leads of the meter on the two clamps (one lead on each clamp) with the meter set to read ohms. It should read something less than infinite, but you would like it to read more that 100 ohms and ideally much more ohms than that, which would mean there was no source draining away the charge. If instead you find that it reads only 5 or 10 ohms that means there is a component that is draining the battery.

The procedure to find out the drain source is to disconnect each of the fuses that are assigned to a specific circuit in the car, one at a time, and see if the meter reading moves toward infinity as the result. If there is no change in the reading of the meter, then replace the fuse and move to the next one in the fuse box and see if it causes an increased reading, etc. When you find one (or more) such fuses that when removed caused the reading of the meter to go up significantly, then look for the label on the fuse box for that fuse, put the fuse back so that the reading decreases again and begin to unplug each of the electrical items that are powered by that fuse and keep checking until you find the item that causes the reading to go up again. That is the faulty component that is causing your problem.
You will want to do these tests with all the doors closed so that no lights are "on" and the car is sitting just as it is when you have it shut down. Be careful not to change anything about the car doors/lights (always close the doors before reading the meter) while you are doing this testing or none of it will make any sense.

__________________
Turn and Burn!

ATLspeed

i say pull the alternator and get it checked (not sure if they can do that for an SR20 ALT in the US though?)

__________________
93 s13 Vert - 2jz/cd009 -- parted/sold
95 Supra Turbo

slider2828

Just for reference I answered him in my PM. You can go to your local mechanic and ask him if he knows of any alternator shops that can rebuild alternators. I believe the housing is physically the same, but the pulleys are different. I to save yourself the headache, just get it rebuilt..... It will look as good as knew.... Ask the alternator shop if they can upgrade the internals too when they rebuild it to get more amps kekekeke! I didn't, but wish I did.

__________________
Turn and Burn!

TTrx7Pete

Well I decided to further inspect my alternator and it looks as if the wires that run from the alternator's plug might be making slight contact with my air conditioning line. I pulled the wires away from it and the car cranked with a jump and ran on its own... It was however only pulling 12V, but the car at sit was only at 10.9V. I imagine its the deficit that the alternator needs to make up in order to obtain 13~14V while running. I'm going to tape off that section with electrical tape and keep an eye on it to see if that was in fact the culprit. I couldn't see any wear on the wires though...

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia

slider2828

Great I am glad....

__________________
Turn and Burn!

TTrx7Pete

Welp that didn't fix anything. I did try something else. I tried jumping my car on the positive cable rather than using the battery and I got a constant 13.5V. Once I put the jumper back to the battery it went to 10.6V. I couldn't get the car to crank, I think it might have flooded. I'm going to give it a couple hours and see what happens next time I jump it. I relocated the battery ground to a different location in the trunk. I'm using a spot that is used by the wiring harness for another ground. I hope it maybe had something to do with that, but I'm skeptical, since I haven't had this issue before and the ground hasn't given my problems before. I can't seem to find anything wrong with the alternator on its face or connections. Something is draining this thing all of a sudden.

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia

slider2828

You should have 7 grounds.

head, block, 2 intake depends on engine, 3 chassis and tranny, battery of course and alternator.

How old is your battery? Is it bulging on the side? get your alternator checked..... Do these things.

__________________
Turn and Burn!

TTrx7Pete

I have all grounds. Battery is brand new. I'll have to take the alternator off and I'll let you guys know.. less I find another avenue to go down.

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia

slider2828

Alternators not too bad....

__________________
Turn and Burn!

st280

Don't know if this applies to you? But had same thing happened to my Sr it sounds like, after I took to a local motorsports shop... They put new belts on my car, and when it was all put back together for 1. They didn't put the bottom bolt on the alternator, and 2. The top bolt was barely hanging on (I believe it works as a ground/timing belt tensioner also?)...

Well anyways I was at constant 11.8V, took to a local alt. shop, they tried to sell me a new one. When I loooked under hood and inspected closer, noticed the top bolt was sticking way out, tightened it up nice and snug, and my voltage went right up to 14V.

TTrx7Pete

I'll check that out...

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia

TTrx7Pete

My bolts are snug.

I jumped the car this evening and it ran on its own pushing 11.8V. I then drove it around my neighborhood for about 5 minutes and achieved 12.8V and dipped into 13V but averaged cruising 12.6V. More and more I think its a bad alternator but the charging lights aren't coming on and the car is draining voltage as it sits... But, I guess if the alternator isn't charging the battery, my battery is taking hit after hit each time I try to start...

I dunno.. any more input?!

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia

slider2828

Not just that, but if your car drains faster than the batt charges up and no matter what car you own, battery is always drained just whether fast or slow, this happens. Fix your alt before you need a new battery..... Constant jumping and draining of the battery really wrecks it.

__________________
Turn and Burn!

TTrx7Pete

Question now is, where do a get a new alternator for an S14 SR20DET or where do I get one rebuilt?!

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia

TTrx7Pete

I can hook up a voltmeter to my battery and slowly watch it drop from 10.10 to 10.09 to 10.08 etc... its sad. This is with the car completely off.

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia

slider2828

Read.............

__________________
Turn and Burn!

sbc

An s13 SR alternator would be fine or you could just modify a KA one.

I had some serious drainage issues to the point where i had to disconnect my battery every time i got out of my car. I stripped the charge harness and it turns out the wires of the two pin plug were exposed and crossed. I guess the 12v was going to the battery light on the dash instead of the alternator. Redid my whole lower harness just for the sake of cleaning it up but I could have just wrapped those wires.

Been perfect ever since.

TTrx7Pete

Had the alternator rebuilt.. turned out to be bad.

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia

RAMM

Im in the same boat as the OP.

BUT, i just had my alternator replaced and the car is doing the same thing. First my gauge cluster went out, then the car started to die out as described above. I had my old alternator checked and my batter and they both turned out OK.

Any ideas on if the gauge cluster could be directly correlated to my major voltage loss?

TTrx7Pete

Do yourself a favor and take the alternator to a rebuild shop just in case. Most of the alternator testers at autoparts stores suck. Also do check for open grounds. Look for anything causing a short. Are you blowing fuses?

__________________
1993 AW Mazda RX-7
1997 Nissan Silvia