freq

iTrader: (6)

Starts up fine, idle's for about a minute or a little less, then dies.
Seems to be an electrical issue.
Other symptoms:
From time to time, I turn the key and nothing--as if the battery isn't connected. I immediately try it again and usually turns the starter within 1 or tries.

Possibly unrelated: logicon gets power 50% of the time.

Can someone point me in the right direction as to where I should start looking for the cause?

freq

iTrader: (6)

.

Gen2n3

iTrader: (1)

Freq,

Verify that the Negative (-) battery cable is not kinked, bent, cut, or broken. Do the same with the Positive (+) cable to and from the battery to starter & alternator. If this is an intermittent problem then you may have to wiggle/shake/rattle/roll these cables to ensure nothing is broken. Have you read the schematic and took any measurements? Examine the starting/charging schematic for more help.

If your logicon is not getting power, chances are it needs to be re-worked. They are notorious for poor/cold solder joints. Do a search for one of my How-To's on it.

Let us know what you find!
Cheers,
George

freq

iTrader: (6)

Got a working logicon-working now(tho the blower doesn't work, but that's an unrelated issue), also replaced the heater coil so I pulled the dash and redid some wiring while it was out.
Checked the Negative cable-not kinked, bent, but or broken. Same with the positive cable. After I get the interior back together and set, going to do another check of the wiring in the engine bay.

Gen2n3

iTrader: (1)

Freq,

Thanks for the update. When you checked the Negative & Positive cables, did you also check them going to and from the starter? I'm curious, why did you replace the heater core and what's the problem with the blower motor? A replacement Logicon may be all you need. Since you have a replacement Logicon, have you opened the bad unit to check for bad solder joints? Could the Haltech ECU cause the intermittent starting issues you are experiencing? Do not discount the importance of the Body CPU when starting the car or when other electrical gremlins start to appear. The Body CPU controls the theft-deterrent system and may cause starting problems or even drain the battery. Have you followed the Engine Electrical System checks in the FSM?

Cheers,
George

Hot_Dog

I've too have had some weird intermittent electrical problems on my 90 GXL. Clock would go on and off, lights would sometimes dim when I hit the brakes, I'd turn the key and nothing but try again and it starts, etc. I decided to change my battery cables last weekend. I disconnected the original cables and ran new cables along side the harness. So, I bought zinc battery terminals with wingnuts on top, bought 2 prefabbed 49" 4 awg cables with lugs, and fabbed 8 awg positive and negative cables with lugs. The 12" 8 awg positive ran from the (+) battery post to the fuse box next to the battery, and the 16" 8 awg negative ran from the (-) battery post to one of the strut mounting bolts. This solved my electrical problems. Big improvement in my electrical system performance.

freq

iTrader: (6)

Y, did check them going to/from the starter, but will be checking again when I get the interior back together. Replaced the core because antifreeze was leaking on the floor. Replaced the logicon because was intermittently not powering at all. Opened it up and tried resoldering with no change in symptoms. After put the new(used) logicon in, found that the light green/black wire was intermittently getting switched power. Setup a relay and sending it switched power independantly fixed that(at least until I have the time to figure out why the ltgr/blk wire was intermittent). The Haltech ECU is one fo the few electrical components that seem to be dependably working at this point. The stock ecu harness was one of the first things to go last year. A new Haltech with a harness was only a few hundred bucks more than a new fc harness alone, so considering the ecu has numerous programmable engine protection functions(overheat/overboost, etc) in addition to traction control, boost control was a no brainer.

pfsantos

iTrader: (1)

I'd say ignition switch. Try to repeat the problem when it's running by wiggling the ignition key.

freq

iTrader: (6)

Already replaced with a new unit.

Gen2n3

iTrader: (1)

Freq,

I (and the forum) look forward to hearing more about your wire repairs with the dash out. Please take & post photos to help tell the story. If you haven't already, take a look at my Logicon repair thread to identify potentially bad solder joints. Nice work on running a relay for switched 12V to the Logicon. When you installed the Haltech with wiring harness, did you draw out unique schematics for future reference? How easy was replacing the heater core with the dash out?

Cheers,
George

freq

iTrader: (6)

Off the top of my head in the past several months...

A couple months ago, the horn stopped working, so rather than deal with re-soldering the stock relay/circuit board setup, I bypassed and replaced with a relay.
https://www.rx7club.com/2nd-generati...em-cpu-828928/

I found that it's helpful to label replaced wires for future reference.
$12.99 labeler
I label at both ends(at least) of the main wires to make it fairly apparent what they are for/where they run.

I don't have time right now to fully diagnose the heater blower issue, so I setup another relay and a switch to send power to the thick Blue plug on the ExHi relay that sits on the blower. It only gives me hi, but it's starting to get pretty cold here, so that'll do for now.

Several months ago I had problems with the stock security system going off every once in awhile, so I unplugged the harness behind the glovebox.

I still need to figure out which wire from the logicon engages the ac clutch as my ac isn't working and I can't find the wire that's supposed to send power to the clutch in the engine bay.

I've got a re-amemiya front end with dual headlights, so I think the extra draw ruined my light switch..twice. I found out the hard way, that the harness usually needs to be replaced too so, that's 2 rebuilt headlight switches and a new harness.

While the dash was out, rewired my gauges -- boost/oil pressure/water temp/fuel pressure/wideband.

Will prob rewire the aftermarket radio power and front speaks next week.

Interestingly it seems that the heater core was designed to be removed without pulling the dash. On the driver's side, there's a cover that is attached by 2 phillips screws. Remove that and you have full access to the core and the valve. It's a little uncomfortable working it from the floor, but much easier than pulling the dash and having to deal with 30 year old brittle plastic trim and support pieces.


That's under/behind the dash. Engine bay wiring is yet another story ;-).

Gen2n3

iTrader: (1)

Freq,

It sounds like the Body CPU is partly responsible for some of those electrical gremlins - horn, security alarm, etc... Have you ever given much thought about its repair or replacement?

That's a lot of work (and love) put into your dash repairs. I'm sure the car appreciates all the work you put into fixing it up.

Good advice on the heater core, I believe others suggested a similar approach to installing a replacement.

Best of luck with all those repairs and I hope to read more about your fixes in the future!

Cheers,
George

freq

iTrader: (6)

Y, I considered repairing the body cpu unit, but reasoned that if I can get the same functionality out of a relay then it's a much easier/cheaper repair now and in the future. I onlly wish there was a more reliable replacement for the logicon.

pfsantos

iTrader: (1)

Compared to the stuff you've done, I'd say fix the solder joints in the CPU. Seems very within your abilities.

One note about the horn. If it stops working right after doing some work on the front end (bumper off, rad, condenser, etc.), make sure you didn't switch the A/C pressure switch plugs with the horn plugs. They're similar.

BTW, did you mod the harness to the Headlight switch to use a relay?

freq

iTrader: (6)

N, actually I'm looking to do that mod as well. Is there a writeup?

Gen2n3

iTrader: (1)

Freq,

pfsantos is right. It sounds like the solder joint repair is in your wheelhouse. If you have any issues, take some photos then send them my way. I may even be able to help re-solder the joints.

Cheers,
George

freq

iTrader: (6)

That repair may have to wait awhile. This is my daily now, so now that I've got heat, I've gotta get the traction control wired up and configured so that it's good for winter, and the power steering went out on my wife's rx8 so i'll be pulling that rack this weekend.

pfsantos

iTrader: (1)

RX-7 Headlight Switch Harness Relay Mod | stanis.net

Wut? Are we still talking second gen rx-7's?

freq

iTrader: (6)

FC with a Haltech Elite.