NewZed

Fuel pressure too high? If you have an aftermarket pump and a blocked line or regulator, pressure can get very high. Temperature sensors lost continuity, sending "cold, give gas" signals to the ECCS?

I think that Tony D might be trying to point you to the TPS. The TPS tells the ECU when the throttle is at idle position. At idle, the ECU adds enough fuel to allow the engine to idle. At about 3/4 throttle it adds a lot of fuel so the engine can go. I haven't tried but I've read that the engine should run, at least idle, without the AFM connected. Yours doesn't so the place to look is the TPS. My 76's AFM number is A31-060-001.

It says rough on the zccjdm page that the 280Z AFM won't work on a 280ZX. The inverse should be true. Did you measure the resistance across pins 6 and 8, and 8 and 9? What were those numbers? Your fuel pressure is high, as you noted. If the gauge is between the filter and the rail, there would not be much pressure drop to the injectors. If it's before the filter you could get a high reading. High fuel pressure will richen things up. The main reason to "tweak" an AFM is because an engine wasn't running right. Sounds like buying someone else's problems. By the way, nice formatting on your message, but a few capital letters might help you get more responses. Effort returned proportional to effort in. Just my opinion. I think the mods have given up on grammar policing, they're overwhelmed. No caps really only works for e. e. cummings...

CTRL -, 0, and + will resize the viewing area if you're using Windows. Unfortunately it resizes the text also but it's a quick way to get a look. CTRL 0 takes everything back to where you started. Google's Picasa is free and will download from your camera and export to a smaller, predefined size. Kind of clunky but it works - http://picasa.google.com/#utm_campaign=en&utm_source=en-ha-na-us-bk&utm_medium=ha&utm_term=picasa

Si. Maybe there have been more measured results than have been posted in the thread. I just haven't seen many focused results, like actual temperature measurements at the back cylinders, or running more races before the back cylinder exhaust valve seats loosen up, or more boost possible since the modification, or similar. It seems like many people are doing this but it's not clear if they're really getting any benefit. I'm just trying to draw out some more before and after anecdotes about this proposed improvement. Something measurable. Maybe some of the other people who have done this will post their results.

Sounds like something electronic. Solid sate devices do strange things. Grounding the coil warms up the ignition module and the Pin 1 ECU circuit.

In the Factory Service Manual (FSM), Air Conditioning refers to air heating also. The section is full of drawings and descriptions of how the air heating and cooling system works. http://www.xenons30.com/reference.html The 1977 download file doesn't unzip in to chapters, so it's a little more work to find what you want, but 76 and 78 do.

I've read the whole thread and it has drifted some from the original Post #1 (not surprising after 22 pages) but Ricky's post has kind of brought it back on topic, to specific problems at the back cylinders. Ricky stated that they "added the by-pass lines after we had some issues with the engine losing compression on those cylinders which was caused by the exhaust valve seats losing their seal. We used a vacuum gauge to test the valve seat to confirm this." He then reports a stable 190 degrees after ten laps as the result, as opposed to creeping up over ten laps. The question of compression loss and loose valve seals due to localized heating is still unanswered. If this mod has fixed that, then the engine should produce more power over the course of the race (no more compression loss), with no loose valve seats at the end. That would make the result of the modification more clear. I've read the whole thread before and I recall waiting for the definitive results to solving the dropped valve seats, or detonation at 5 and 6 problems, but never really saw it. The closest I recall was a report of producing equal, sharp, "sudden onset" detonation across all cylinders. Anyway, thanks to everyone who does this kind of work and shares it. It's fascinating stuff and I wish I had the resources myself to add more to the discussion.

I thought that the focus of this thread was to find a way to prevent overheating at cylinders 5 and 6, to avoid problems like dropped valves (Post #1) and detonation. Ricky is just reporting a lowering of coolant temperature in general. Which seems a little odd actually, since the same volume of water is flowing past the temperature sensor and the same amount of heat should be produced by the engine. It's interesting work, but I don't see the connection between specific hot spots and overall heat removal.

One possible reason for the engine to idle higher with the flasher fuse out is that the alternator is not working as hard (burning up your wires). Did the ammeter wire smoke before the fuse box upgrade? There's a pretty good wiring diagram at this link, in the FSM - http://www.xenons30.com/reference.html

The descriptions of wire gauge in the FSMs, plus the Courtesy Nissan web page support the premise that Br (Brown) is actually what is now called red and is 0.3 mm^2 in diameter. http://www.courtesyparts.com/kb_search_result.php?chassis_id=59&keywords=fusible+links&Submit_Button=Go&cat=1 I think that Post #12 in your first link is on the mark. The wire gauge is listed in the FSM. The only reference I have seen on the internet to red as 50 amps is the atlanticz site, and on the atlanticz site, they call red out as 0.69 mm^2 not 0.3 as Hyuri says (in your link). It would be great if blue would address that issue someday on the atlanticz site, since tens, hundreds, maybe thousands of people take it as Z gospel. Luckily it only really matters if you have a short. It's interesting that the ZX fusible link cover still shows Br for link color, but the stock link looks red.

Here is a starting point for you - http://www.xenons30.com/reference.html Good luck. You'll probably be in the Tool Shed by end of day. Do you have a 5.0L 240 - 260Z or is that your plan? Edit - I'm a slow writer. At least he finally got a couple of responses.

Your jumper wire just did the same thing the fusible link did. It melted because it had too much amperage through it. The components on that circuit,including your fuel pump, should not be pulling enough amps to melt the link or the jumper. There must be a short somewhere in the circuit. By the way, red may not necessarily be a 50 amp link. There is some confusion about it in the 280Z world. I'm not familiar with ZX's though, but you should probably confirm it or you might melt the next weakest link in the circuit with your 50 amp fuse. The wiring diagrams should tell if one of the components that you upgraded has a direct connection to ground, that you might have reversed.

The fact that "sometimes" you have to push the pedal to the floor suggests that your slave or master cylinder is going bad. Pull the rubber boot off of the slave cylinder and see if it's full of fluid. I had a slave cylinder fail due to bad sealing mid-stroke. It looked like it was moving correctly but it was leaking in the middle of pedal travel. If you're sure the hydraulics are good, then it's possible you have a short collar in place when you need a long one. But if that was the case, I would expect your slave cylinder piston to get pushed out of the cylinder since it is self-adjusting and would just take up the slack (as I understand it). Here's a link to collars either way - http://zparts.com/zptech/articles/trans_swap%20parts/4tobear_specs1.html Edit - these are examples and your situation might not be shown, but it gives you the idea.

These are popular - http://forums.hybridz.org/index.php/forum/63-ems/ There are threads out there about the Z31 ECU but I'm not sure it's much easier, better or cheaper than the aftermarket options in the sub-forum above.

If he still has the external voltage regulator, you might check that out also. One of the wires to the regulator is hot, a direct connection to the battery. Unplug it and see if the light goes out.

How about a picture of the debris from the header?

You might have a broken tension rod on the front suspension. They break sometimes if the rubber bushings are replaced with urethane. A broken rod will let your transverse link (aka control arm) and wheel move back and forth. Just a guess, but worth a check.

WB02 means wide band oxygen sensor. It allows a higher resolution signal to be produced than with the narrow band, and with the right controller gives actual Air Fuel Ratios (AFR) over the useful range that you would expect from a well-tuned engine. Here's a link to one of the most popular units - http://www.innovatemotorsports.com/products/lc1.php Here's one with a gauge - http://www.innovatemotorsports.com/products/MTXL.php One more thing - the graphs in the link below show what you are probably reading, either narrow band or wide. The slope of the curves, negative vs. positive, is even different for narrow vs. wide. You should figure out what you have. http://www.carcraft.com/techarticles/116_0402_innovate_air_fuel_ratio_meter/photo_07.html Just one example. Not an expert, just stuff I've picked up here an there.

This thread should help you - http://forums.hybridz.org/index.php?showtopic=48124 Since I'm here - what do you mean by "2t" in your description of your engine mods?

CSV is Cold Start Valve but maybe the turbo motor doesn't have one. I browsed the supplement and didn't see it. Confirm fuel pressure. Just loosen a hose clamp on the fuel rail and see if gas squirts out. Your FPR and pump should hold pressure for at least a minute or two after trying to start. The dropping resistors save the injector circuit from overheating. I would not run with them bypassed if you have stock injectors. Alright, that really is all I know. Good luck. Confirm fuel pressure.

You're welcome. But. I think that dropping resistors are matched to the injectors (according the FSM the 81 turbo engine uses a dropping resistor, it's described in the 81 Turbo Supplement) to control current flow through them. The ECU or E.C.C.S just supplies the ground. I could be wrong though, I don't have a turbo motor. You could check you CSV connection for 12 volts when the key is at Start, then pop the CSV out, disconnect the small wire to the starter so it won't crank, turn the key to Start and see if the CSV squirts. Or loosen the hose clamp and see if it leaks, or something similar. A lot of different ways to verify some fuel pressure even if you can't measure it. On the 81 doesn't the fuel pump prime for five seconds when you turn the key to On? You should be able to hear it. I would think that if you had some fuel pressure in the lines, that the CSV would supply enough to at least give you a pop or two. Some people have reported running the engine on a stuck open CSV alone. You might supply a direct 12 volts to the CSV, jump in and see if it starts. Just a wild idea. That's all I have. It sounds like you have everything covered except confirmation of fuel pressure in the lines and injectors opening.

This thread has some good stuff in it. Jump to #16 for the apparent answer. You might have enough current for the lights but not enough to open the injectors. http://forums.hybridz.org/index.php/topic/97671-1977-280z-fuel-injection-problem/page__p__917068__fromsearch__1#entry917068 Are you sure that you have good fuel supply and pressure?

Maybe they were monitoring a converted signal from the Megasquirt board, not the actual VR output.

The variable reluctor generates its own voltage. There is no +/- 5 being turned on and off. (Edit - on the oscilloscope) The Megamanual does a pretty good job of explaining it. http://www.megamanual.com/ms2/pickups.htm