Keep at it- you'll figure it out and we are here to help!
In situations like this, I like to start at the beginning and assume nothing. What is known:
The engine will turn over but not fire. Even a drippy injector or bad plug/coil in a cylinder or two will still result in a start or at least a sputter. To me, this means the starter circuit is fine, but the engine isn't getting any fuel, any spark or both.
FUEL
Step 1 is the ECU. If the ECU isn't working, the engine will not run because it will not get fuel or spark. When you turn the ignition to run, you should see the check engine light illuminate for about 2 seconds and then turn off. This is the ECU check routine. If the light never comes on, the ECU is not working. It could be something as simple as a loose plug/shorted wire or bad as a fried ECU. The ECU troubleshoot list starts on page 11-26. Assuming you get the light, go to step 2.
Step 2 is the fuel pump. When you turn the ignition to run, you should hear the fuel pump run behind the firewall for a few seconds and stop. It's a humming noise. Turn off the climate fan to help hear it. If you don't hear the pump, check the following:
- Fuel pump wires behind the driver's seat that go through the metal plate (could be chewed)
- Fuel pump relay- also behind driver's seat. Test is on page 11-101.
- Fuel pump- test is in page 11-102. If you get more than 11.2 oz of fuel for the 10 second test, then you know that fuel is at least making it through the rails and the regulator.
Step 3 is the main relay. The test is on page 11-103. An easier way is to find a friend with a known good relay to swap. If the car starts, there's your problem! I can send you my spare from the Zero for testing if you want.
Step 4 is the fuel pump resistor. A bad resistor shouldn't prevent a start, but the engine will not run. It will start, sputter and die. But it's still worth checking. Test is on page 11-106. Also look for frayed or cut wires where they attach to the resistor- this is a common problem on the NSX.
Step 5 is the fuel injector resistor. If this unit is faulty or the wires are damaged, then the injectors will not fire. Look for damage to any of the wires and then do the tests on the bottom of page 11-90 to 91 and 11-94.
Step 6 is the fuel injectors. Do the resistance test on the top of page 11-90 for each injector. Though, if the engine isn't starting at all, I doubt all 6 injectors are bad. Still, assume nothing and test them all. Check the wires for damage.
Step 7 is the fuel injector signal wires from the ECU. Do a continuity check for each injector to make sure there is a clear signal to each injector. Again, a failure on one or two of these wires would not prevent a start and it's unlikely all 6 wires are chewed, but assume nothing and check them. The manual (page 11-91) requires the use of the ancient and unavailable ECU tester, but you can use a multimeter and just check pin-to-pin.
If all of these tests check out, you've confirmed 100% that the engine is getting fuel inside the cylinders and you can move on to spark.
SPARK
Step 8 is the ignition signal from the ECU. In Step 1 you confirmed the ECU is functioning. Thus, we know it will send an injector pulse signal out. Now, you need to check if the signals are making it to the ignitor. Do a continuity test (page 11-57) to check each wire.
Step 9 is the ignitor ground wires. If the ignitor ground is bad, it will not fire to any of the coils. The test is on 11-57 and there are two black wires. Make sure they are not chewed and securely bolted to the ground point (G103 shown on page 23-92) on the intake manifold.
Step 10 is the ignitor itself and the output wires to the coils. The test for the unit is on page 23-93. I know you already tested this, but test it again. Assume nothing.
Step 11 is the coils. At this point (assuming the ignitor isn't bad), you've established that there is a clear signal and power getting to each of the coils, so you know there is the correct voltage at each coil harness plug. Now you need to check the coils and plugs. Again, it's highly unlikely that all 6 are bad, but test them (page 23-95). Check the plug color and carefully measure the gap.
If you have gone through all 11 steps and it all checks out, then the engine should run, even if it runs poorly. Given that you just went through a TB/WP job, my suspicion is that you forgot to plug something back in or attach a ground somewhere. Running through this progression should catch the culprit. Generally, you should make sure the main harness engine grounds are attached as well- there's one under the coolant bottle from the transmission, and depending on year, one on the upper firewall coming off the front cylinder head or one/two attaching to the right side body next to the alternator/fuel lines.
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