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While there are many proven aftermarket improved output alternators there is currently a brand selling on Amazon called "Eagle high amp (200amp)". I decided to try one of these units out while putting my build together. After rebuilding the engine, and installing the SBG IGN1a coil kit I was finding that I was killing IGN1a coils at a wallet draining pace. While chasing what I believed to be ground issues I managed to burn out 8 IGN1a coils thinking I had solved the issue by correctly grounding the coils per the manufacturers recommendations rather than the standard SBG coil harness method of grounding. Grounding wise I had already run 4 gauge grounds similar to this post:
After walking away from the car for about a month due to work after thinking I had solved the problem, only to melt the T1 coil in a catastrophic fashion during a test drive (made it 1 mile). I ordered a new coil, and on a whim decided to put the stock alternator back on the car since it was a variable that had changed since the last time the car ran. I also checked the plugs before starting the car again and noticed that the front rotor plugs seemed to be fouling, but the rear rotor looked fine. Took the car out for a 10 mile drive and nothing melted, zero issues car runs fine.
The only thing I changed between coils failing/melting and coils running/firing properly was the alternator. I'm morbidly curious what an alternator shop would find if they bench tested this Eagle high 200amp unit, if it's built wrong, or simply too many amps for the wiring in the car. I'm not sure what the problem was with that Eagle alternator but I would recommend anyone looking at one to be cautious about it, and look at some other proven higher amp alternators for FD's. For now I'm just going to go with what works.
7 of the coils burned out non-catastrophically, they would overheat by the time the car warmed up, would stop firing, and then you would see zero resistance between the A/B pins on the coil. However during the test drive the T1 coil actually melted, but the other coils were fine and are still running on the car now.
Last edited by F1blueRx7; Jul 19, 2020 at 02:14 PM.
Reason: http formatting issues
interesting. the stock coil/ignitor setup has a capacitor in the circuit (i think more for noise suppression) does the SBG kit?
second, i work at a big auto parts wholesaler, and we sell a stupid amount of alternators and other electronics for German cars (is like 10x, sometimes 100x, its crazy), my co-worker has an idea that it has something to do with the quality of the electricity. if we were to upgrade this to a theory, we would go test a stock Mazda alternator, which will usually last the life of the car, and our best selling one. the Mazda part would have a smooth stable voltage, and the best seller would have voltage spikes, thus killing stuff. so far its just an idea, to make it a theory we would need an experiment and repeatable results.
I don't think the problem with your coils has anything to do with the alternator change. Even if that Amazon alternator was total garbage, its claimed output current rating is irrelevant here. An alternator will only produce as much current as all the loads in the car's electrical system can draw from it, up to its design limit. And IIRC, the OEM FD wiring puts a 125A fuse on the B+ output wire from the alternator which would limit you to that anyway.
From what you've described, I'd suspect a inherent wiring problem with your coils, probably with regards to how they are grounded and/or how you're supplying them power. Assuming you have the coils on their own power circuit, protected by a breaker or fuse, the fuse/breaker device should have tripped long before your coil melted down like that. Got a detailed wiring diagram of the actual install you can post up?
I don't think the problem with your coils has anything to do with the alternator change. Even if that Amazon alternator was total garbage, its claimed output current rating is irrelevant here. An alternator will only produce as much current as all the loads in the car's electrical system can draw from it, up to its design limit. And IIRC, the OEM FD wiring puts a 125A fuse on the B+ output wire from the alternator which would limit you to that anyway.
From what you've described, I'd suspect a inherent wiring problem with your coils, probably with regards to how they are grounded and/or how you're supplying them power. Assuming you have the coils on their own power circuit, protected by a breaker or fuse, the fuse/breaker device should have tripped long before your coil melted down like that. Got a detailed wiring diagram of the actual install you can post up?
I'm at a bit of a loss. It's the Sakebomb garage IGN1a kit with plug and play IGN1a wiring harness I didn't do anything custom with the harness until after I started having coils fail. I definitely have the OEM condenser still present and grounded. re-grounded the IGN1a SBG harness per the instructions here https://www.rx7club.com/haltech-foru.../#post12407489 and here: https://www.rx7club.com/3rd-generati.../#post12417363
After I did that it was only the T1 coil that melted down. I replaced the plug, and wires with spares that come with each new coil, replaced the alternator and no further issues. I can only correlate here, and I lack the ***** at this point to try and prove that it wasn't the alternator because of the expense I've already gone through. It's possible that the A/B pins on the SBG harness at the T1 coil plug were shorting out since that was the only one that melted after I separated the B, C and D ground pins for each coil.
I have the new ARD 150 amp alternator.
Its fully warmed up output voltage is 14.2 while my OEM was 13.7.
Stock T1 coils are known for frying. I use a TII T1 coil which is very robust.
This was my 1st thought - too high voltage output. I.e., the regulator is controlling at too high voltage. Amperage is controlled by what the draw is on everything consuming electrical power. The voltage is the key, IMO.
This was my 1st thought - too high voltage output. I.e., the regulator is controlling at too high voltage. Amperage is controlled by what the draw is on everything consuming electrical power. The voltage is the key, IMO.
That is a very good point I overlooked - too high a supply voltage and/or too long of a dwell setting can roast these coils. Easy enough to test for though. Put the questionable alternator back in, start up & take a voltage measurement.
