Boaty Posted May 30, 2012 Report Share Posted May 30, 2012 So, here's something for you smarties out there. Got on it tonight... noticed that at or about 6K RPM, everything dies. Lost dash lighting, headlights go out, engine I can't tell if it's cutting out or not with the straight pipe exhaust I have at the moment. It's only momentary, however - lights come back and everything is normal within a second. It only dies for maybe 1 second at the most, and ONLY around the 6K rpm mark. I haven't brought RPM's higher (no reason to.. not even for the lulz) to test if it stays off. My GUESS is it's the alternator but it could be vibration from something. Just putting some feelers out there... anybody ever experience this before? I'd hate it to be an alternator, it charges great and steady @ 14.6V, sometimes it takes a little throttle blip to start up though (CHG lamp stays on). Looking for some ideas on things to look for, I'm going to go through and make sure everything is hooked up and didn't come loose after driving it today/yesterday. FWIW it's an S13 KA24DE with KA alternator. Feel free to share some experiences! Quote Link to comment
DAT510 Posted May 30, 2012 Report Share Posted May 30, 2012 My old Z31 would die completely from a vacuum leak. at around 6K. This was at full throttle, and then suddenly letting off. It's most likely not the case here as your car turns back on. Quote Link to comment
68Datsun510 Posted May 30, 2012 Report Share Posted May 30, 2012 Thats freakin weird. Your battery should supplement the alternator... This sounds like a very loose wire Quote Link to comment
Boaty Posted May 30, 2012 Author Report Share Posted May 30, 2012 I hate that guy. Quote Link to comment
philcas1987 Posted May 30, 2012 Report Share Posted May 30, 2012 with all this lame ass wiring problems just rewire another harness for gods sake! Quote Link to comment
Boaty Posted May 30, 2012 Author Report Share Posted May 30, 2012 Not the harness, though lol. I'm thinking loose cable sounds right. Might be losing power @ the alternator, we'll see... they power stud is super small copared to the #6 cable feeding the battery. Quote Link to comment
ggzilla Posted May 30, 2012 Report Share Posted May 30, 2012 Not the alternator. You can disconnect the alternator, then try it. It will run off the battery for 30 minutes or so. Quote Link to comment
banzai510(hainz) Posted May 30, 2012 Report Share Posted May 30, 2012 ggzilla The lights went out. which is wired directly to the battery that should be separate from the engine dying issue. its loosing POWER form the starter lug to the fuse box. Or a massive short for a spilt second what makes it look like the lights are going out. first I thought rev limiter. but lights went out. With a good battery and the fusable link hooked to the battery power will be on if the light switch is pulled(unless this has a alam and now usues a switchable ground to make the lights go ON/OFF when alarm is triggered) Most use the High beam lights. But this is just info This is just my opinion from afar Quote Link to comment
Boaty Posted May 30, 2012 Author Report Share Posted May 30, 2012 Well this is how I have this set up. Battery is in the trunk. The starter and charge/power circuits are separated, with a Ford solenoid in the trunk near the battery. At the starter, it's jumped from the cable to the starter solenoid and the ford solenoid in the rear is trigged by the key in START. Totally isolated. The charge circuit goes from battery to a 175A MEGA fuse, then to a power bushing on the firewall, and from there directly to the alternator. Main power for the car is hooked up @ the power bushing on the firewall (original +12 that went to the alternator + the additional 12ga wire I added on the fuse box with the screw terminal IN the fuse box.) Main power cable is #6ga. Headlights are hooked up @ the alternator stud (relay power for low beams) at the moment. Since it's RPM dependent, I am wondering if it's not the alternator. It was weird, as I expected everything to die and stay dead, but the power loss is momentary. Comes back up, everything is charging just fine, no flickering, no nothing. Alternator doesn't surge though, I expected it to if it was the alternator. This is a tricky gremlin! I am thinking massive short, like Hainz said. That was what first came to mind for me, we'll see. I know it's not enough to kill a 175A fuse at least (I plan on ramping that down, 175A was all that was there at the time of purchase.. thinking 125A). The reason I thought maybe vibration is doing it, is because the car just aboslutely RUMBLES, haha. Poly engine bushings + no exhaust makes for some serious vibration at the moment. Exhast appointment is 1 PM tomorrow afternoon. Quote Link to comment
banzai510(hainz) Posted May 30, 2012 Report Share Posted May 30, 2012 OK this helps alot. Try durng the daytime not using your lights,heat ect... How about try hooking the battery back up to the stock battery hook up and then run to 6K and see if it happens again. You just might be overloading the alternator to where its shutting down. Or if you have a a volt meter see if it loads down the higher rpm you go.Of coarse with lights ON ect....... Sice everything is now off the alternator Thats what Im thinking it is. Im not totally familiar with this set up as I would think the charge wire is hooked up to the battery and thus would take care of any over thraw of the sysytem. But IM only really guessing unless I see a circut in front of me. I know Baz sells these and I have posted these battery islation systems before from the net soemwhere Quote Link to comment
ggzilla Posted May 30, 2012 Report Share Posted May 30, 2012 You just might be overloading the alternator to where its shutting down That won't cause a loss of battery voltage. It's not the alternator. More likely to be loose connections at the alternator, battery cable ends, starter, or engine to body ground. Quote Link to comment
68Datsun510 Posted May 30, 2012 Report Share Posted May 30, 2012 ^^^^^^ You need a LOT of good grounding with an EFI engine. Dan Gallmeister told me he had to have 3 ground straps, engine, bellhousing and back of trans area. Crazy, but it worked! Quote Link to comment
ggzilla Posted May 31, 2012 Report Share Posted May 31, 2012 You only need ONE good ground for an EFI engine. Three grounds are needed if the other two are not GOOD grounds. A lot of cars have two grounds for redundancy Quote Link to comment
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