I had gotten everything hooked up, and after splicing about 25 wires last Wednesday and spending almost all of my free time the rest of the week and Saturday debugging the TPS and MAP sensor wiring, I got the car to a point where it would start, rev to 1500 for a few seconds, then die, without my touching anything. If I tried to keep it alive with the throttle, it would just die all the more quickly. I wired up custom harnesses, bypassing the main harness from the sensors in question to the ECU, to no avail–same deal.<\/p>\n
It was clear a couple of days ago that the harness on the car, pre-extended by a gentleman in California but of questionable quality, had a short or a crossed wire somewhere in the loom, not to mention the glove box area was a rat’s nest of splices. I had visions of wrestling with the harness for a few more days, getting the car running for another week, then getting inexplicable electrical issues that put the car out of commission for months or worse, damaging the engine. I did not want this. I had spent about 30-35 hours on the car in the past week and was getting extraordinarily frustrated at its lack of cooperation. I had a couple of options:<\/p>\n
1. Go standalone. MoTeC makes aftermarket ECUs that would adapt to the 1JZ, and the Haltech E11 will actually even use the stock Toyota coils, ignitor, CPS, and include a base fuel map, enough to get me to the dyno so I could work the rest of the fuel and ignition curves out. The processors inside either unit are light-years ahead of the ~1990 programming in the factory ECU. Going standalone is arguably the acme of my tuning goals–it’s something I’ve always wanted to do.<\/p>\n
2. Pull the existing harness completely off the car and rewire everything from sensor to ECU, doing it right, no splicing, but solid wires, shielded where necessary, soldered, heat-shrunk, and zip-tied. This has the advantage of being free, minus the wires and such, and I have wiring diagrams and pinouts already for the ECU. It also doesn’t require any tuning after the fact. Double\/triple check everything, hook up connectors, and turn the key. Hopefully.<\/p>\n
3. Triple blow-through Webers, a la early Esprit Turbo. Just kidding.<\/p>\n
So it looks like no.2 is the way I’m going. I don’t want to have to take off the upper intake manifold but it looks like I’m going to have to.<\/p>\n
On the plus side, I’ve gotten a set of mk4 550cc injectors (straight drop-in w\/resistor pack) and mk3 Supra-specific coilovers for really cheap. The shocks are gone on them, but hopefully that should be a simple matter of finding replacement cartridges. Also, for the little time the engine was alive, the car sounded beautiful, what with the 3″ HKS downpipe and GReddy catback. Very deep and powerful–nothing raspy or tinny about it at all.<\/p>\n