FastWoman

Yes, fresh gas through the injectors and fresh air through the intake manifold will cool the injectors. On my engine, the problem disappears when I first take off down the street. It takes much longer if I just let the engine idle. Revving the engine is also of little help, perhaps because the engine isn't under load and drinking quite as much fuel.

Crazy, yes, you would get a bad reading, but only if you are smart about how you catch it. What you should do is to make sure the black smoke is coming out of your tailpipe before you shut the engine down. Do not do anything else. Proceed immediately to the critical measurement: WITH THE IGNITION *OFF*, pull the ECU connector, and take your #13 pin reading. If it reads normal, plug the connector back in, and start the engine. Does the engine still blow black smoke, or does it run normally? You want to find agreement somewhere. You can also take the other approach and clean/replace any connectors that look questionable. My own CTS and thermotime connectors were pretty crusty/crumbly. If yours look like mine did, I'd replace them anyway. The problem might go away. The other things I'd check are the throttle position switch, the air temp sensor, the AFM, and the cold start valve. (Check the CSV to make sure it's not stuck open. Check the AFM vane to ensure it doesn't stick open, and check its connections to make sure they're good. Check its potentiometer board to be certain it's clean and in good order.) As Zed suggested, it could also be your ECU, but perhaps not as likely. Give it a few bumps/kicks to see whether that kills the black smoke.

I bought the premium 2.5" exhaust to fit the OEM manifold and put a Magnaflow 4" midpipe muffler in the middle. It's a reasonably well behaved exhaust. It's a bit rumbly at idle (maybe more than I'd like), but it's quiet (enough) when driving. It does drum a bit just after startup when the engine is stone cold. I had someone with welding skills (a local Z specialist) do the installation. He told me that the fit around the transmission can be difficult, depending on the transmission. Apparently later model transmissions are dimensioned a bit differently and can present a bit of an interference problem for the exhaust -- or so I remember him saying.

Yes, fuel injection rated hose. It should cost in the neighborhood of $4/ft. I've used both the type with the blue rubber inner lining and the type that's just black. The black is sturdier, as the blue rubber lining can become separated. I'm running those injectors in my car and have had no problems with them. They've been in service for about 1.5 years now. I once read someone complaining that some aftermarket injectors they bought were not balanced with each other, spraying different amounts of fuel. However, judjing from plug color, all of mine are spraying the same -- just right. BTW, I was very pleased with this style of clamp, which comes in various sizes: http://www.summitracing.com/parts/CCA-G3912/ It won't bite into the rubber, and it's flexible enough to make a good seal on small hoses.

Here you go: http://atlanticz.ca/zclub/techtips/afm/calibration/index.html For $155, you can buy all new injectors: http://www.ebay.com/itm/75-76-77-78-79-80-81-82-83-Datsun-280Z-Fuel-Injectors-/160661473384?pt=Motors_Car_Truck_Parts_Accessories&fits=Model%3A280Z&vxp=mtr&hash=item25682b8868 The hoses might be a bit short on these. (They were on mine.) It's simple to cut them off and install longer ones, though. Cut the hose reinforcements with shallow, grazing angled cuts, and then pull off to the side. Don't nick the aluminum barbs!

I would bet money that you have a bad connection to your coolant temp sensor.

Racebird, you can simply judge by ear. With the throttle in the same position, and adjusting the timing, the faster the engine runs, the higher the vacuum. I would suggest putting a timing light on the system to at least see what 10 deg BTDC does for you. However, some of us run a bit more advance. I think I'm running at about 13 deg BTDC. I wanted to advance enough that the engine felt like it was running happily (i.e. wasn't completely happy at 10 deg), but I didn't want to keep advancing after that. I stopped advancing when I felt I was starting to round the corner of diminishing return, if that makes sense.

Tomo, as you know, my Z is a '78. I did an HEI retrofit. I mounted the module where the connection box is located for the distributor pickup. I disconnected, removed, boxed, and stored the OEM IM. (It still works, but not very well.) The system works well. I just bought a cheapie, plain vanilla HEI module ($11?) and have had no issues with it. I'm not a high revver, but the module certainly hasn't given me any problems up to maybe 5k, which is about as far as I ever rev the engine. I'm pretty sure I wired it as you diagrammed. No ballast resistor, MSD flamethrower II coil. I mounted it to a power transistor heat sink and made sure I had a really good ground (important). It doesn't look stock, but it doesn't look too bad either. Someday I might give the module its own box, but for now it's just hanging on the underside of the mounted heat sink with the wires clipped on.

Eric, I hate to throw cold water on your low compression/vacuum theory, but when the vacuum runs weaker, the fuel pressure runs higher. In the end, the pressure differential along the path of the fuel -- from rail to manifold -- is kept constant, so that the amount of fuel injected is a function of injection pulse width and NOTHING ELSE. I do believe our slightly low engine vacuum does relate to our somewhat low compression, though. It's just engine wear. When our engines run less efficiently, the vacuum is going to be lower -- probably from more blow-by. Predictably, the vacuum issue is mostly at idle, not at elevated RPMs. I have a theory to compete with your low compression theory, and I have no hard data upon which to substantiate it. I wonder whether most or all of our late-model ECUs tend to have this problem, and most people just don't realize it. (In my experience, linear circuits tend to drift and fail in the same ways from unit to unit, usually at substantially the same rate.) When I bought my car, the PO represented it as running great. Indeed, it ran well enough to drive it hundreds of miles home. The car had been professionally maintained by a Nissan mechanic with whom I had a long chat on the phone. To him, the car was running fine. For many people, a car that starts and runs until the key is turned off is a car that runs great -- even if it's not running efficiently, and even if it's lacking power. I suspect the unaffected cars are simply not running quite lean enough to start popping, and they're running well enough to satisfy the professional mechanics, but I bet they're not running all that great either -- at least well enough to satisfy fussy people like you and me. The thing is, I don't think most people expect an antique engine with 150k+ miles to get up and go. Racebird, try the potentiometer fix. I think you'll be pleasantly surprised. :-)

Er... Eric, my memory was a bit faulty. According to my service records... " Took dry/warm compression, 10 strokes. #'s 1-6 = 165, 165, 168, 173, 165, 168." I guess that's reasonable for an engine with 173k miles on it.

The problem with old cylinders is that the key guide also wears out, so that you can eventually start the car with a house key, screwdriver, or popsickle stick (yes, I've done it). If I were you, I'd seriously consider replacing with new.

Eric, I did do a compression check. I got about 185 across all six, dry. What's your theory? Black gold, the intake pop occurs because an overly lean mixture can burn extremely slowly -- so slowly that there's still a bit of fire after the end of the exhaust stroke and into the beginning of the next intake stroke, thus detinating the fuel/air in the intake manifold. If you advance the timing, you give the mixture a bit longer to burn before the next intake stroke; however, this addresses the symptom, not the cause. Racebird, the injectors should put out a nicely atomized spray pattern, not a stream. Perhaps you're due for some new injectors. I use a set of Standard Ignition injectors I bought off of Ebay for $150. The rubber hoses are a bit short and need replacement, but otherwise they work fine. The same vender still sells them there. I like to measure vacuum at the nipple that feeds the HVAC control systems -- the little nipple next to the brake's power booster vacuum line.

Early VIN numbers were devoid of much useful info. HLS30 means the S-30 body style (the 240Z, 260Z, and 280Z -- i.e. through 1978). Then 4679 means the obvious -- the 4679th one produced. That's all. I'm not too familiar with the 240 specifically, but if it's like a 280, there's a color code sticker in the engine compartment on the frame member just forward of the radiator on the passenger side. There's also a plate on the driver side of the engine compartment with the original engine number and other other specs. The number of the engine is stamped on the passenger side of the engine block. For $20k, the car should come with pretty complete records. Check those too. The conventions might be a bit different on this particular car, as it's a JDM (Japanese Domestic Market) car -- sort of a rare bird around here. Consider the righthand drive carefully. Personally, I think I would almost never pass another car if I were driving on the right. I also can't imagine shifting with my left hand, although I suppose I'd eventually get accustomed to it.

Yup, the same. I'm using an '81 ZX FPR on my '78 Z. I think the turbo version might be different, though.

Yikes! Yeah, argneist just disconnected the EGR as well. Of course this is thread drift, so we can leave it at that. Racebird, I tried a different ECU as well, and I found my car ran exactly the same way. It took quite a lot of diagnosis to determine both ECUs had drifted lean in exactly the same way. My chief suspect was the AFM, but it checked out in every possible way, and indeed it operated exactly the same as another AFM I ordered in. How are you measuring your fuel pressure? You should measure it with the vacuum line disconnected to get the proper static reading. A reading of 32 would probably be about right for a vacuum reading of 10 in Hg or so.

Phew! One case is a fluke. Two would be troubling.

Awolfe, THANK YOU!!! This be bity bity good karma!

Captain, a locksmith can replace the ignition cylinder for you with a new one (i.e. re-using the old lock body). I think I paid about $45 for this. You can also order made-in-China door locks off of eBay. They're OK, not great, but certainly worlds better than the original worn-out locks. There are also some new/old-stock hatch locks available, although they're a bit pricey. A locksmith can key all the locks to the same key for you. Be warned, though, that there are two different key styles. Check photos very carefully for the groove patterns before you order. A locksmith can put either style of cylinder into your ignition lock housing. (The new cylinder is made in China/Taiwan, BTW, but it works fine.)

I suspect higher octane gas might also help, as it tends not to be as volatile as lower octane gas (pretty sure).

Blue, I do remember the weird EGR to intake hole in "argneist's" intake manifold (a '78, as I recall), but I don't remember that happening with HealeyZ. Now TWO cases? Interesting. Racebird, Cozye and I went through all of this in a long thread of mine named "purs like a kitten," which you can search. We both concluded, as have others, that the ECU can drift in its operational properties over the decades. This would make it like almost any other elderly analog electronic device I've had the pleasure of servicing.

Your cam turns 80 RPM, i.e. 160 RPM at the crank? Not bad! Video????

Sure, that will work, but there are two potential problems. First, the potentiometer could get dirty and/or become deteriorated in that position. Few potentiometers are designed for that sort of environment. If you decide to place it there, consider using a 20-turn trip potentiometer and wrapping it into the harness with electrical tape (to protect it) after you're done with the adjustments. The second problem is that it doesn't allow for convenient adjustment while on the road. As I described, I wired an extension cable to allow me to make adjustments in the passenger seat while someone else drove the car. That was a nice feature. PS Sorry for being slow to respond. I've been away from my computer, in another location, refinishing floors.

Even after you set everything right with the old L-Jet EFI, you might find the mixture is still off. There are no intended adjustments, aside possibly for the idle mix screw at the bottom of the AFM. I don't find that it does much. You can also change the mixture by: -- adjusting the tension on the AFM clock spring -- described in an article on Blue's Atlantic Z site. I wouldn't use this for big adjustments. This only works for low to moderate throttle. If you're really cranking the engine, the AFM will be pegged out anyway, and for RPMs above 4500 I think the AFM is ignored anyway. -- adjusting the fuel pressure with an adjustable fuel pressure regulator. An adjustable FPR usually isn't as precise as Nissan's stock FPR, and it will not hold pressure after shutdown. You're also limited in your useful adjustment range. Again, you don't have a lot of latitude here, but the adjustment will work uniformly throughout all aspects of the EFI's operating range. -- wiring a potentiometer in series or in parallel with the coolant temp sensor to increase or decrease the resistance of that circuit, respectively. This will either richen or lean the mixture, respectively. This adjustment will impact the mixture the same way throughout all aspects of the EFI's operating range, but it will somewhat diminish the mixture accuracy during engine warm-up.

I think the cold start injector only sprays fuel when the engine is below 50 deg F, so that's not likely to be a factor in a warm engine. The cold start problem seems to be a fuel starvation problem anyway, most likely from hot injectors. Sadly, I've come to the conclusion there isn't really a good solution. My engine runs like a top, and I've got all new injectors and a new check valve. My system holds pressure just fine. I'm also in the weird habit of priming my engines before starting, even when it's usually unnecessary. So I hit that primer switch (that I installed) just prior to starting my Z -- every time. I've also insulated my fuel rail, although perhaps not well (with rubber hose, wrapped in silicone rubber tape). Even so, I'll occasionally get the rough start after 15 or 20 min of sitting. I think it's just the nature of the beast. Wait another 15 min, and it will probably start just fine. Also try a different gasoline. I think the cooling fan would fix the issue, but I'm not willing to have a ZX look under my hood.

Sweet! On a completely unrelated, but somewhat similar note, I just moved. My neighbor across the street in my old neighborhood had a beautiful, yellow '68 Camaro daily driver, so I was looking forward to having the only cool classic in the neighborhood. Nope! In my new neighborhood, my next door neighbor has a very nice DeTomaso Pantera in the garage -- yellow, of course. I don't think it runs, though.