NewZed

The Factory Service Manual (FSM). You can open the relevant chapters here - http://www.nicoclub.com/datsun-service-manuals

Pages 1982 EL-32 and 1982 EFEC-96 should help you out. It will take more effort than typing out "because" though. Probably hard to see on your phone also. A volt/ohm meter at the ECCS plug and those two pages should be enough. Good luck.

On the New Content page, on the left, do you have Forums chosen? Might have blogs or some other odd thing. If I choose Blogs or Downloads or Calendar, I get no content.

I just clicked it and got three pages of New Content. Windows 7 with Google Chrome browser.

Actually that's not clear from the Nissan service specs., and that's where the confusion comes from. Plus the fact that some BW manual transmissions specify Dexron, according to the interweb. See attachment for Nissan spec. Notice that Nissan calls out the automatic transmission specifically right below the manual transmission spec. It's just a poorly written specification. Here's a pretty good summary that throws in the confusing point with no clarification. World class versus non world class, but who knows if that's true. Nissan calls out either fluid in their spec. Maybe Nissan used both WC and NWC in their turbo cars and the owner is supposed to know which they have. It's a mess. About paragraph 7 - http://www.hemmings.com/mus/stories/2007/05/01/hmn_feature21.html

This is one of those threads that could ramble around for weeks, but just for curiosity what is unknown about the injectors? Do you have a part number? Are they the stock injectors for the engine you're using? Turbo injectors? Or truly unknown? If you have the wrong injectors for the EFI system you're wasting money buying Seafoam.

How do you calculate mpg from 100 miles? Now seems like the right time - http://www.mycyclonefuelsaver.com/howitworks.html

Last post - I think that the 5 that's measured with the factory system comes from the ECU. You have a 12 volt supply on your pullup line so should be seeing 0 or 12, I believe. The 5 volts that you're seeing might be a coincidence. The voltage is not generated from within the distributor, it's just allowed through. The 5 and 4.75 you're seeing might just be the result of a voltage drop (from 12) from a short somewhere. Another guess. Sorry to clutter up your thread.

You've probably seen this or something like it. Zero or five seems like the right numbers. http://my.cardone.com/techdocs/PT%2031-0002.pdf Edit - note that the test is with everything plugged in.

Might as well post this for photo-diodes. It seems like the Nissan system would just put out a voltage, with only power and ground. Maybe it's between tach wire and distributor body. Almost the bottom of the page, Optical Triggering. Don't forget that MS is set up with VR trigger even with an optical distributor. http://www.megamanual.com/ms2/pickups.htm Good luck.

What happens to resistance on the tach line with power and ground connected to the distributor, but nothing on the tach line. If it's a switch like the HEI module it will go from low to high. The FSM says it's a pulse,which may or may not be a voltage. Maybe you just need a bigger pullup resistor. More guesses. At the bottom of Moby's writeup he says that a 2K resistor is for 12 volts and the 1K is for 5 volts. From the writeup: ____________________________________________________________ *Pullup/Pulldown resistor quick course You use a pullup resistor to get your line(or pin,connection) to some voltage (5,12, etc). Suppose you want a pin to have 5volts. If you just add a wire to 5 volts there is nothing to limit the current and if the pin happens to be an input to a transistor that is switched to ground then you have a short to ground from 5 volts and you burn stuff up. So instead you add a resistor to the 5 volts and the resistor will limit the current according to ohms law. Current is voltage divided by resistance. If you put a 1k ohm resistor to 5 volts then if the pin is switch to ground by internal electronics it can only draw 5 milliamps max(the resistor current-limits the path). A pulldown is similar except that you want a pin/wire connected to ground and you want the path to be current limited. To size the pullup or pulldown correctly you should know what the circuit is that you are adding the resistor to. But as a general rule you can use a 1k resistor for 5volts and a 2k resistor for 12volts. That limits the current to a few milliamps which is conservative. Sometimes the circuit may require more current to operate properly.

What happens if you just measure voltage at the tach signal to ground, with power and ground to the main distributor wires? I'm just curious as to how the tach is designed to work. The FSM implies that it outputs a voltage on the two output wires, zero or something (1982 EFEC-61). I think that the pullup resistor might be for the Megasquirt side, not the distributor side. Maybe. I thought I understood the pullup resistor for the HEI module because it pulls up one circuit (G and W) so that it can control the other (B and C). Normally G and W would have negative and positive voltage from the VR pickup. I don't get the purpose for the distributor tach line, since the "control" is from the other side. Unless it's completing a circuit to ground through the tach line and somewhere, like the distributor body. Just thinking in writing. Is your distributor body well-grounded? Maybe you're missing a ground circuit somewhere. Don't place too much value in any of this. Basically, I'm just bumping your thread until someone who knows speaks up.

Edit - I don't know enough about electronics to guess anymore. I would certainly try to isolate the distributor from the other components though. Don't test with everything connected together. Interesting problem. Good luck.

It's easy to mis-visualize the parts.

The simplest test for you would be to view fuel pressure when the problem happens. Get the vacuum number from your dash gauge and the fuel pressure number from another and you'll have numbers that tell you something. The standard practice is to T in a service gauge and run the hose out of the partially open hood to where you can see it while driving. Your idle numbers don't show anything wrong. But, more to the point - does the engine run differently above 4000 RPM? You never really said. Or are you doing all of this work because your AEM gauge shows a number? You might just have an exhaust leak.

Do you have a good ground on the tach's ground wire and on the pullup resistor? I'm more curious now just to see what you're doing. The details aren't clear, no way to tell what you really have wired and how.

Where is this Aeromotive filter? Before the pump or after? The stock Nissan pump is huge so that it can pass enough fuel to support the engine while still filtering. You might have the wrong filter. The high impedance injectors won't hurt anything but if you left the resistors in place you're running less current through the system, including the ECU, than designed. Your pressure and intake vacuum numbers don't add up but 38 psi would be sufficient pressure to make things work right. 19 inches of vacuum is 9.3 psi. 38 - 9.3 = 28.7. Your picture of the gauge at idle shows 25. Probably just two bad gauges, combined, or the camera caught a bounce. Who knows. If the lean-out happens even when you work up to 4000 at part-throttle then the TPS probably isn't a factor.

No, the suspension systems changed in mid-1974.

The small market may lower the value of time spent returning e-mails and responding to queries. I didn't get any replies either. Maybe one of those "here if you want it but we don't have time to support it" deals.

About halfway down the first page in this link there's a diagram (little yellow box) showing the distributor wiring. Connect power and ground to a battery and measure voltage on the "tach signal" from the distributor while you spin it. If you get the zero and five, then your problem probably isn't the distributor. You might need the pullup resistor to get a consistent signal. http://forums.hybridz.org/topic/23244-megasquirtnspark-mssmsns-installation-guide/

Your 25 psi at idle implies 22 inches of intake vacuum, which is very high for the 280Z, I believe. And you should have seen 36-37 psi when blipping the throttle. Disconnect the starter solenoid wire and turn the key to Start. The fuel pump will run but the engine won't turn over. Or disconnect the vacuum hose to the FPR while the engine is running. You'll get full pressure on the gauge, it should be 36-37 psi for a stock regulator. Why not use the FSM or the Electronic Fuel Injection Guide to know that the TPS is right? The early one was written for your car. Test at the ECU connector. http://www.xenons130.com/reference.html Those Ford injectors are one lb/hr higher rate than stock. You should be running rich. Are they low or high impedance? If they're high, did you bypass the stock resistors in the power circuit? Maybe the injectors aren't opening correctly. Just some possibilities.

Compare your diagram picture in Post #2 to diagram in Post #1 here - http://forums.hybridz.org/topic/23244-megasquirtnspark-mssmsns-installation-guide/ Here's a followup thread to that one with more information - http://forums.hybridz.org/topic/56329-megasquirt-overview-for-newbies/

Megamanual? You haven't described the ignition module, igniter, coil driver, IGBT.... What is supposed to be controlling your coil?

No gauge, it's all guessing.

If you grease the steering rack bushings well they will squirm around to fill the gaps when driving. I had about a quarter inch gap I couldn't close but just torqued bolts and drove. They're elastic. They fit perfectly now.