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Found 6 results

  1. Hello all, I'm struggling with a recently acquired, stock 78 280Z running very rich. As in 13-15 mpg combined, and all plugs are getting carbon fouled to the point one or more start misfiring completely. I changed the previous owners BPR6ES with fresh BPR5ES plugs, but after around 1000 miles I could again hear the 5 cylinder "brrt-brrt-brrt" and soon after the 4 cylinder "cho-cho-cho" ? I've been troubleshooting using my multimeter and the 1980 EFI bible, it's all well within specs except for the test 1- (3b) - Air flow meter resistance #2 (ECU pins #7 and #8). It gave a reading of 360 ohms, well above the 150 suggested by the bible. I pulled the AFM to test it more thoroughly according to the FSM, which gives the following instructions: 4.: 12v DC to terminal #6 and #9 5. Test voltage between terminals #7 and #8 6. Gradually open the flap and if there is a proportional decrease in voltage, the potentiometer checks out. And it did check out, the transition was really smooth. But I have no idea if the start and final voltages were within spec, as they arent mentioned in any of the manuals. With closed flap the differential was 8 volts. +8 at #7 and 0 at #8. At full open it was +8 and +8 for a 0 volt difference. Still not convinced everything was as it should I tested the resistance again. And this time it was 180 ohm, almost within spec. Weird. So I gradually opened the flap fully, and the resistance jumped erratically back and forth between 200-500 ohms. Then I closed the flap and made a new measurement: 260 ohm. Repeat: 230 ohm. Also confident the fault is not in my multimeter, it's brand new and doesn't hesitate measuring the correct resistance of anything else. So naturally I'm wondering - is my AFM actually working as intended? Or is it broken, but perhaps fixable? And if broken, is this the likely source of running rich? I haven't yet opened the AFM to fiddle about inside, but it certainly looks as if someone else has in the past.
  2. Hey everyone, I have been a long time lurker on many forums and I have decided to post some questions because I am at the point where I believe I need guidance on next steps and want to make the right decision. The car I am working on is a 78 280z California Car. It is not my car, it is my parents car that I bought them as a gift 10 years ago. It has been a long time since I have driven the car so I don’t recall its characteristics but it always had a presence of fuel smell in the exhaust. The car was parked because the fuel smell and rough driving started getting worse. The car then sat for a year and a half and now its time to get it back up and running. All the items addressed have been done within the past four months. Disclaimer: There is a lot of information here and if I am unclear on anything please let me know. I am trying to get some conversations going and wanted to put my best foot forward. Symptoms Bogging/hesitation/stuttering under any load to the point where the car can’t be driven, can’t emphasize this enough. Car idles immaculately Backfiring through the AFM Fuel smell through exhaust Current State Timing: 10° BTDC Idle: 800 RPM Aftermarket exhaust header and muffler EGR deleted Air regulator removed Coldstart injector still on rail but disconnected electronically Thermotime switch disconnected electronically Items that have been addressed Spark: New Plugs (NGK at .039in gap) New Wires (NGK) New Coil (MSD Blaster) Rebuilt ZX distributor (RockAuto) Vacuum advance confirmed working New Cap New Rotor Fuel: New fuel injector connectors Injectors reconditioned from Fuel Injection Services (confirmed working) New Walbro 255 fuel pump Tank removed and checked for rust Fuel hard lines cleared with compressed air New fuel filters (pre and post pump) Inline gauge added between filter and rail Air: AFM has been calibrated per atlanticZcar site rebuild guide Bench tested for smooth sweep (open to close) Calibrated spring force with water weights New PCV valve Engine: Valves adjusted to: Intake: .008in Exhaust: .010in TDC mark confirmed correct on main pulley Distributer shaft confirmed 11:25 position Leakdown test performed Compression test performed Electrical: New coolant sensor New coolant sensor connector New TPS wiring connector Contacts cleaned with deoxit ECU Harness tested in car to EFI Bible specifications Results Leak down and compression test performed cold because the vehicle was not running at the time. The AFM sweep was performed using a 9VDC battery and an arduino. I did two sweeps of the door by hand as smooth and slow as possible. The third sweep I intentionally pulsed the door through the sweep motion by hand to see if something else would happen. I did not see any signs of a bad circuit. The FSM provides a table relating resistance to temperature for the air temperature sensor and coolant temperature sensor. I generated a chart using this data in both °C(Blue) and °F(Orange). The trend is not linear so a polynomial trend(Thin Orange) was generated so I could plug in a measured value to determine a temperature. The table also provides acceptable ranges within specific temperatures so I added error bars to show this acceptable range. The test environment(Green and Yellow circle) was what the temperature should be and the measured (pink) value was within the error bar at that condition. I went through the circuit testing per the FSM and found nothing alarming. Observations Advancing the timing beyond the timing marks helps but doesn’t resolve the overall issue. Timing at 10° makes the car impossible to drive. Timing at 25°-30° makes it bearable but only above 30% throttle. Future State I have worked through what I believe to be the cheapest items to inspect and now believe it is time to find a new AFM and ECU set. Everything appears to be correct and by the book. Should I try to find a 78 280z ECU/AFM for a CA car, or should I find one for any 280z car (non CA). I have toyed with going standalone because at this point I am tired of poking around in the dark trying to troubleshoot this car. I need some assistance from people who have experience with the FI systems on these cars and I don't know anyone locally to reach out to. If I am unclear on something, please ask and I will provide.
  3. Hi all: I searched here for the answer, and I Googled a bit for a source. But no luck so far, other than Ebay, which has connectors that don't look the same as mine. I noticed on my '77 (that I just bought) that the AFM connector does not seem to have any retaining means in the AFM. If I unbolt the AFM, the connector falls out as soon as I move it. I'm concerned the connector will fall out while driving. Is there a source for a replacement connector, aside from getting an entire harness? I can't even tell what is supposed to retain it. But I assume this is not an uncommon issue. Before I shell out $300+ for a harness, I'll explore a home-made solution. But I'd rather replace the plug (or whatever retains it if that can be retrofitted). Thanks in advance, John.
  4. Hey guys (and gals), I'm the new proud owner of a 1977 280z. I don't know a ton about cars, but I'm mechanically handy and I have downloaded and read through the FSM and the FIB for the car. When I first got the car, it had been sitting for a year and wouldn't run at all. After replacing the fuel pump, it starts and runs, but very very rich. It fouls all 6 spark plugs in short order and idles very rough, occasionally dying. I first suspected the CSV, so I disconnected it with no success, though the engine still started fine so I have left it disconncted. Then I pulled the CSV to see if it was leaking fuel, but it was fine as well. Next I checked the water temperature sensor and air temperature sensor, which reported 2520 ohms and 2260 ohms at the ECU in around 68 degree weather. Finally, I ran through most of the ECU checks in the Fuel Injection Bible and while the air regulator circuit failed, it would result in an overly lean fuel air mixture, right? I rented a fuel pressure gauge, at idle between the fuel filter and the rail it was around 32 PSI, which I know is slightly low. Since it's a new fuel pump, this makes me think that the fuel pressure regulator is suspect. Would a messed up FPR cause a low fuel pressure and make the car run rich? I checked the fuel return line to the tank by blowing in it and after momentary resistance, I could blow through. I also put the fuel pressure gauge between the rail and the fuel return line. There it indicated no pressure. I then pulled the line while the engine was running and very little to no fuel was being returned at idle. I pulled the cover off the AFM, all the contacts look good, the flap moves freely, and the glue blobs all appear untampered with. At idle, the flap moves about 1cm back, though if I finger it to the lean side, the car runs much smoother. I've considered tweaking it a few teeth toward the lean side, but I would rather get to the root of the problem. A few other things I've tried: adjusting the idle screw with no real change, pulled the oil cap while idling and felt vacuum resistance plus it ran worse, visually inspected all vacuum lines and tightened hose clamps, and examined the electrical connections. I'm sure I've tried a few other things and forgotten to write them down, but please suggest any boneheaded thing I may have missed. I feel like my problem is with the FPR, but most of the threads I've read on it say your car will run leaner when the FPR fails. I've also considered replacing my water temp sensor even though it tested fine at room temperature since it seems to be a likely candidate. I know I probably need to check my vacuum pressure next, but I wanted to consult the gurus here before I spend any more money.
  5. Hello everyone I am needing a 1982 280zx turbo AFM, wire loom and ecu. I have a 1975 280z that has an '82 turbo transplant. Problem is that the air to fuel ratio gets lean at higher rpm's. Which is why my pistons are melting and broken:tapemouth. So I figure this may be the best solution, unless someone here has a better idea with what I have to work with. Note, I have not look hard into mega squirt yet. but lets start here first. Thanks. Big Al.
  6. Hi new to the forum, I have a 77 280z 4sp sat for 15 years, worked on it every few years because of fuel problem. getting divorced and need the car, had choice keep wife or car chose my z. Initially removed tank had it boiled and lined car still didn't run. Now I have discovered fuel tank is blocked internally, so I installed a new outflow line threw drain plug of tank, blocked existing outflow line. Installed new fuel pump,, changed plugs filter, car started right up and ran rough but ran. Problem is now that after driving a couple miles the car hesitates, backfires some when driving and then doesn't go, and drops to idle, i step on gas idles goes up abit then down to idle. I then turn car off, and restart it a couple minutes later and its fine again for a little bit, replaced pump and get 36 lbspressure, fuel seems to travel throughout lines, I am getting spark,Can it be something electrical, or module, relays? when opening the door on AFM the pump starts. I'm sure more info is needed to diagnose. I've been searching the forums but haven't located answer yet and I have to move the car. Thanks Aleck
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