NewZed

Sounds like the fairly common "heat soak" or "hot start" problem. Search those terms on the interweb and you'll find some good reading. What you describe and what you say the previous owner described look like two totally different things. Your problem is immediate, his/hers happened after 10-15 minutes of proper running.

Maybe it is running really rich. What's the fuel pressure? What did you do with the gas tank vent lines when you took the canister out? Did the gas smell exist before you made these changes?

Gasoline in the oil? I filled a crankcase full of gasoline once with a borrowed carburetor that had had the float bowl needle removed. Small block chevy so no external leakage was evident.

Probably waiting to see what happened this morning. Did it thunk? Metallic is usually clang or clank, not thunk. So that part was a little confusing. Free turbo engines...I'll take one too.

The NA 280Z EFI system is not a good way to run the 280ZX turbocharged engine. You could have a mismatch between the ECU and: the injectors (they're higher flow rate on the turbo), the TPS (three position for the Z, two for ZX), the CAS (not connected in your case since the 280Z ECU doesn't use one), and many other components. You probably already know that people will recommend Megasquirt. After re-working everything to use the 1980's technology, you'll still have just 1980's technology. The first thing that you should do is make a list of the parts you have. Engine block, pistons and head (P90, flat-tops, dished pistons, etc), CAS, TPS, turbocharger, turbo control pieces, etc. Then you'll have an idea of how to get things working right. You should stop trying to drive the car in the meantime. It's pretty easy to damage the L6 with with a turbocharger, especially when it's being boosted over spec., using the wrong ECU, and a bunch of mismatched parts. All you really have that's useful is a car and a turbocharged engine. Looks like your car could use a lot of work. It's not stock by any means so the factory service information won't help a lot. Post #31 in this thread. "Perfect" is a relative term, even though by definition it's absolute.. http://forums.hybridz.org/topic/67930-in-progress-75z-getting-81zx-turbo-motor/page-2?hl=scoutman75

You're probably just measuring at the wrong pins, or wires. The drop to 4.75 is probably "on" and 5 is "off". There's a voltage drop when the photo diode is switched, I would guess. I wish I had one of these, they look like fun to play with. Nobody ever shows what wires they're measuring so this problem, and any solutions, never get clearly explained, I think that what Nissan calls a photo diode is actually being used as a photo transistor. When the light from the LED hits the photo diode, current flows and it's "on". LED light goes away, it's off. Or it may actually convert the light to current but that seems like it would be a pretty weak pulse, converting one LED light in to a pulse. Who knows for sure... Anyway, draw up a diagram, or take a picture and show where you're measuring voltage. There are guys on this forum who know exactly how these things work. Note that there are actually two different wave forms generated. Ideally, you would confirm both.

The 85's you two are comparing are probably from weather stations in the shade at about 6 feet high or more.

If you prop the throttle blade open far enough your ported vacuum becomes full-time intake vacuum. Could screw up some other functions.

You've just re-invented throttle body fuel injection, abbreviated TBI. Hit the Google to learn more about your new old idea.

Looks like two separate problems, as implied in Post #6. Shift linkage, or shaft misalignment, inside the transmission, and bad or un-bled clutch hydraulics.

The curve is steep and not super accurate.

The factory option, same concept.

That's one way. The ECCS system probably runs the CHTS ground through the ECU. The better way to confirm that the ECU is getting what it needs though, would be to measure resistance to ground at the ECU plug and compare the resistance to the temperature versus resistance chart in the FSM. Continuity doesn't really tell you much. Study the diagram for the ECCS ECU and you'll probably be able to figure out which pin is ground and which is the temperature circuit. Check resistance of your other ECU grounds while you're in there, you might have high resistance on the main ground circuit which is giving high readings from the CHTS.

Check for continuity to ground on the other side of the connection at the CHTS. The ECU sends a voltage out that passes through the CHTS on its way to ground. One pin to the ECU, the other to ground. No ground is like no CHTS.

Stuff to check. Highlighted the non-electrical. Note also that their web site says the pumps are rebuildable to "as-new" condition. Polymer wear plates worn, perhaps. Q. Why is my fuel pressure too low, or I have no pump pressure? A. Check the voltage to the pump, relay switch. Could be faulty. They can be bad without going out. Weak relay reduces voltage. Replace them. Check wiring, look for an improper ground. Check the battery voltage. Check the filter and inlet line for obstructions. Look for leaks on inlet side. Adjust bypass. Is there debris in pump bypass (poppet). The bypass valve could be stuck open. Clean filter. Replace deteriorated fuel-cell foam. If no pressure, the pump may be operating in reverse. Check the wiring diagram. No fuel in fuel cell, or fuel cell improperly vented. http://magnafuel.com/support/index.htm http://magnafuel.com/products/efi/pumps/MP-4301.htm

Seems like you're focusing on spark but the problem might be with fuel. You said it started and idled, and that you have spark. How old is the fuel in the tank and carbs? How strong is the spark? Strong and blue or weak and orange? Modules have been known to partially fail. You might check spark and timing would be with starting fluid. Have someone squirt a few shots in while trying to start and have them try to keep it running with the fluid if it catches.

Can't remember something that wasn't mentioned. Your first post sounded like you just put a new system together, with old relays, and had problems. If it's a new problem on an old system that used to work, that's a whole different thought process. So, is everything 3-4 years old, and the problem is new, just out of nowhere? Or are there new parts, and a new problem? Did the relays you changed have any effect? Correlate the changes and a cause-effect relationship might pop out. Good luck. Don't get side-tracked.

Just to focus a little more, the extra juice when running directly from the battery is probably over-powering the blockage. It shouldn't take 10 seconds to get to 42 psi. You might be overheating the pump due to low flow from a blockage or a too-small inlet filter. The key though, is that you hear the pump spinning and you're not getting pressure. There's something odd about the specs on that pump though, The Summit Racing site says it draws 14 amps at 45 psi. That seems like a lot of amps. Anyway, try it without the pre-filter and see what happens. http://www.summitracing.com/search/product-line/magnafuel-protuner-750-series-in-line-fuel-pumps

Learned this trick on a different forum - right click on the image and you might get an option to search the internet for that image. It works with Chrome, I don't now about the other browsers. It worked for your image. https://www.google.com/search?tbs=sbi:AMhZZisCEH6AzzhnafBNrxStSiX8zrZAv9KVcbTg3tBwGznxnxEA2s6MSlDdQ_1Pt3W_1mYKa7eypuNyaWIF9rI3a1fiCbRa0LiNi-3_1CyB1cyy-uAVQxZOWYKNfmcy4cDCNGP4hI6Le0pnqHujN8mSzpxO-qs5k48wF0YOyWqf9gXnpog9dSqTDoSZY5mhdqTGk95rlYJMMiF4mqywHy03VpFUr1Cekhy-R1ZzNmY8yLjuQynGELvi5B9nmVa5FLADul3g3BE0HgyHdq4S68T7Gzzp_1vdP4600B93BAj8iFQAquM69Y2jpJKn88z8H6pMLeQMTI8ms8FzslimjzPLRWjL4CF_1H9hi6IDZqVgo49on0ksQk3LXO_1OA5RcFzUAZbxRUZJpvRegqHozfcWWlp8IoU2WlYHmYtVHjevS6J-D_1p4R0dQI2IydBhpYwJqPRmg-Ay8VE1zzrIz2VxzVRi3VXkFQ8I1ReJrsceLCvVsqmMncGFu3NbotN1PRsHOQeySk-0LQIhEQurifKY0LEORCT4FYrMwjSQXKrByKguE6tY_1ZDcGuCmimLOAisPc8KE3-2qGBabg68h94hSJ352D5X2vZk8LImN62eCDXSTBT-vibq5iZ-XjAG6cLvnPT6R4Zy-DF8_1ye2edQhjr4ks4v4j6oXZuB_1k9EfojvgbEFedlJ4K4LL5laVbnMgeJgzHcxCX5sK0sLQlOuHs3Ew8fLwnHRuECHOcdyQMbDfHntu_1L5YVQjbA2zJDKtHuDzDzIYp4MoYb28Ls7JVaxwmeB33MrZBjte_1SlE9Phe5ydLl0OSSOypcPDbO5clEmcgNV-rBvTEGm34610uNmkN1XNaoWSO8jvsVGMVwRW0a2VU5nbkBbvvEOQ5Irlta7lfIiKNFBL4BEt2c8epQxQKcUJvtO-tt2ZQT51_1LWHebwIQ-d6qB_1tpKoT8O5piu_10CMMtetIg7PsK5ZdLIZevA6CQCCIP7adLACZ4hUnhMzr9gqZPXfBDzy0-3YdEuSpX6t5-_1D6qLgRCDBLQvO809w_1_16egzjOwVes0raFvOBWr_1vOZdi2Iiy4B67BhAJfDWOh3eHQMHwuI_1FxHOBW-07gGwzXPGPVku0kO-GPwG6yrERThziV_1wTZ7VZkMKsxO_1i4BUNnhH9gTwcmPqq0uL7ArmgNbBXgJoeXX5stJwKI-z2ZtNw6v6d4abatl8nOzym39-Ff2q6TiM8hrVTB2jsubLnKVfoZsJGlWRjYv-a9s5cK5vJJ-hjT2df504dIVCcpY5gtOg07-iPTnmrXf2xAWvPRAQ6aNafUGVWyg3BJ1fRzmdt1NOjwfAlCp6e9y7LMeaXGIpmVKGlmUTltIePFN5jmWU3Fzs6ggTAApkORuXMAl7c-qJ38p2TXTJAhmy_1t-ZmnViqKg9jqfhaN8t0U9fD1sRGcKoVB-6mFxgvdlvzFo3rGTkRqCf9VXOuopUoWVLL2ZkLr3EBI

It doesn't look like an electrical problem.

None of these threads are any good? http://forums.hybridz.org/forum/35-nissan-v6-forum/

When the engine is running,throttle closed (idle) there's about an 8 psi differential between inside and and out. Your smoke test probably has less than one psi differential, if any at all. Pressurize the manifold with the smoke inside and see what happens. Just a guess. You didn't give any details on what the "smoke test" is.

This thread, Post #15, implies that you only added 100 lbs, if all you did was go from aluminum to iron blocks. You said it had an LS1 before. That 100 lbs seems to be having a larger effect than you'd expect. Is their extra stuff hanging off the front like AC compressors and power steering pumps? http://forums.hybridz.org/topic/59086-enginetrans-weights-definitive/ I'm no LSX engine expert but I think that the blocks for the Gen III engines are all essentially the same. Maybe the ZX just isn't suited for a V8 swap. It would be interesting to know the weight balance front to back of the car, as it sits. Even if you get the heights corrected, you might still end up with a wheel-spinning monster. Here's a good read on what you might have. Maybe you can make some adjustments. Looks like a fun problem. http://www.jagsthatrun.com/Pages/Parts_DATZX_MountingInstructions.html And another - http://www.jagsthatrun.com/Datsun-ZX_Order.html

Does it not move at all, not read correctly, or twitch and jump? I had a combination of ignition module and coil that caused my tach to twitch and jump, and only read from zero to ~1500 RPM. An extra condenser (capacitor - the typical silver can from the distributor mount in this case) on the negative terminal of the coil removed the noise. I couldn't explain the details of why it worked, since I don't even really know how the tach works.

I only posted to help you clarify your issue. You should post in a ZX forum since your problem is with the ZX suspension. Seems like you might also have an issue with motor placement since the LQ4 is not supposed to be that much heavier than an L6 (100 lbs more?). Your front suspension "smash" seems excessive and the back end really shouldn't have raised, unless the new motor was placed ahead of the front suspension center line. I'm no expert though, and haven't swapped a ZX. Give some details on the swap.