Zed Head

That's a good point about the Walbro. Beside that it is way overkill for a stock 280Z engine. I've read about noise but not many overpressure problems though, with the 280Z lines. The 240Zs have problems for sure. Easy to check. The one major problem for a daily driver with the Aeromotive FPRs is that they leak down immediately on pump shut down. This can make hot start problems worse, and next day cold starts also. Even the factory FPRs are a pain when they leak down.

Just watched the video again. I wonder if the AFM is even plugged in. You can check the pins at the ECU connector. Sometimes the plug falls off the bottom when you're reinstalling the AFM. Or maybe the TVS is stuck at idle setting. Something odd going on, it sounds good with no load.

Another way to say it is it should be running much better and differently than the problems you have suggest. I've had the lean problem and it wasn't like yours. It popped back and bucked when you tried to give it gas. Yours is running like it's on 4 or 5 cylinder. It could be fouled plugs but these engines can run really rich, enough to make your eyes burn, and still not foul plugs.

Just watched your last video. Very informative. I don't think it's firing on all cylinders. Could be several reasons. I would confirm that firing order AND rotation direction are correct. Check all of the injector connections. While it's idling pull one injector connector at a time. Each one should cause a change in idle speed. Pull the connector, confirm idle speed change, put it back on. If you find one that seems dead, switch it with the one next to it. They all fire at the same time, there's no order. If the problem follows the injector connector it's that, if not it's the injector. We got way ahead of your actual problem I think, although everything you've done so far will probably help with the fine tuning. But you need to get each cylinder firing first. Another reason for cylinder misfire is bad cam lobes. Could also be improper lash setting. You might check your lash again and/or do another cylinder pressure check.

The ZX distributors and ignition modules are known to be flaky. The distributor has a magnetic ring inside with six spikes that ride very close to the six spokes of the reluctor. The bushings are weak and tend to let the points contact, breaking the magnet. You can usually see that by eye, wiggle the rotor and see if things move. The ignition module on the side is electronic and overheats when it goes bad. One test for that is to spray the module with some sort of cooling spray, or apply an icebag to it. If it responds to cooling that's a sign. It has many of the signs of bad electronic ignition. The coils are durable though, the other parts, not so much.

Don't forget that we're talking about 1978. The cover pops right off of the ECU. Two little screws on the back and it slides off. You can open it up and see where the pin leads are. A good idea to examine anyway, they do get fried occasionally from backward battery hookups and corrosion.

You talk about the idle at different potentiometer settings but don't say anything about what you did while driving. You want to increase resistance until it's drivable. A little bit at a time. Watching your video makes me think that you do things in very large steps. The resistance changes will be fine steps, not big cranks of the knob. Your fuel pressure seems high for the vacuum reading. 18 inches of vacuum = 8.8 psi. 34 + 8.8 = 42.8 psi. It might be that the hose to your FPR has a leak or a split. Make sure that the FPR is getting a godd vacuum source. That should drop your fuel pressure, which will clean up the idle smell. When you open the throttle the FPR doesn't see much vacuum. That's how you can have a rich idle and a lean driving problem. The EFI system needs the fine details to be right.

Are the fender flares stock to the homologation class? Do they call them "over-fenders" in Japan? Never heard of the ZG. That's the thing about scarcity and popularity. Best to be scarce and popular. Scarce and not popular...not so good. "The over-fenders riveted to its body begged for wider wheels, just like the Group 4 cars."

I'm pretty sure that I've tried the whole range of ECU's in my 76 MT and not found any difference. I would guess that differences over the years might just be in refinement and durability. There doesn't seem to be any change in circuitry and the descriptions in the Engine Fuel chapter don't indicate what might be different. Fuel cut, for example, is still at 3200 and restart at 2800 in 1978, just as it was in 1975. There are some errors in things like the cold start valve wiring schematic, that have been discussed before. Much has been discussed but nothing has been demonstrated. Always good to have spares though. I got stranded once, a short way from home, when I was testing my spare to make sure it was good. Forgot to bring the known good one with me. Now I keep a spare ECU behind the seat. You can test them just by letting them dangle by your foot on the connection. They have their own ground. Give them a good workout. p.s. idle is its own little world, entered through the throttle valve switch. Might be a change between years, and CA v Fed. EFI started as an emissions control effort, not performance, so changes for emissions purposes are likely.

Take some pictures and report how it goes. Maybe I'll learn something. Should be fun. Good luck.

You do know there's a shock absorber inside that tube... If it's a gas shock it will extend so even if you could get the hub to drop far enough to split the strut it would be a nightmare to handle. The spring is supposed to come off from the top. Detach the top of the strut, lower it and swing it out to where you can work from the top. Lowering the bottom spring perch will allow you to make the strut much shorter so it will swing out easier.

Here's a set for just $300 each - https://www.classiczcars.com/forums/topic/60663-its-up-for-sale-again/?tab=comments#comment-556415

These engines are tough but I don't think that they're bullet-proof. The overheating isn't a good sign. Over-revving can blow head gaskets. You're way up in the "unless otherwise really necessary" zone. Danger.

Did it take 15 minutes to get fully warmed up or was it 15 minutes of driving fully warmed up then it went bad? Was 15 minutes really 15 minutes? No offense, but it seems like you're jumping the gun, then shotgunning solutions. Let things cool down and see if it is heat related and reproducible. You didn't answer the question about the tach needle either. Could be a carb problem. Good luck. Make sure you can go back after you make your changes, you might end up making new problems.

Nobody's going to complain about putting a V8 in that car... Can you desecrate the desecrated? Sorry, feeling poetic.

This post says about the same as your first post. Revs freely but has no power above 4000 RPM. Don't really see a difference. The tachometer needle is a good clue for spark problems. It's a spark monitor and counter. Might add some detail to "made it worse". The condenser in the distributor is there to give a stronger spark and stop the points from burning.

Interesting thread on a generally similar topic. Pretty sure we've discussed it over here before too. http://forums.hybridz.org/topic/35455-brake-boostermaster-cylinder-options-on-a-73-240z/?page=2&tab=comments#comment-1206765

I see a transmission in the pictures. He doesn't even know! It's a steal...

What is the state of the engine at this point? When did it last have a tune-up, including valve lash adjustment? Last oil change? Did you just buy it? How often was/is it driven? The paperwork says "Fail" on ignition timing. What's that about and what is initial timing? Does the vacuum advance work? Lots of possibilities. Need more info than needs an extra push on the gas when shifting gears. A lot more.

If there's oil to the cam, even a dribble, you're probably fine. The pump is working. And you showed that it would pump a lot at higher RPM with your drill motor test. Once the engine starts you'll be at drill motor oil-squirting speed. People have your problem often, there are very similar threads out there.

Not super clear that you mean the dash gauge or something else. Could use more detail than "nothing". Not clear what nothing means. Do you mean no reading at the dash gauge or no oil through the cam holes? Or something (nothing) else? But the sender and gauge are notorious for reading low and responding slowly. You could disable the ignition system (pull the coil positive wire) and spin the engine with valve cover off to be sure that the oil pump drive gear is working. Spin the engine with the starter and watch the cam holes. I've done that on my garage engines, with a ZX reduction starter, which is slow. It works, oil oozes out at starter speed. You could also get a mechanical gauge and mount it in the sender port, to get a faster reaction.

I think that CO is referring to part of the original problem, the reason for parking it, above. I saw the same conflict. The question might be what "rough driving" means. It's a dilemma because it might have just needed a good tuneup, if it was running well before. The OP was pondering buying a new AFM, after "calibrating" the existing one. So the $5 AFM tweak would be a good diagnostic tool. It might not solve the popping problem, but if it doesn't a new AFM probably won't either. The basics need to be covered first though, like fuel pressure. Get it driveable, then worry about gas smell, seems reasonable. A non-drivable car with clean exhaust isn't very valuable. There are other ways to get backfiring, like cross-firing plug wires.

"Slalom" might be another word for autocross. Or vice versa. You'll need to find some ID marks on it to know for sure but I'd imagine a slalom grind would have lots of mid-range torque and a smooth power profile across a wide RPM range. For high-quality throttle response and steady power application. Not a high RPM, high power, screamer cam profile. There is usually a mark on the back of the shaft, stamped or scribed.

The engines are very sensitive to even small vacuum leaks. Removing the PCV hose is a huge one and lets umetered air in. The engine leans out when that happens. The vacuum gauge might find large leaks. One test for vacuum leaks that I use is to run the idle speed screw all the way down. The engine should die from lack of air. If it doesn't there's a vacuum leak. If it does, any leaks are probably very small. Good luck.

And this. It's a driver... Anybody know Bill Breedlove?