FastWoman

Two problems come to mind. First is that there isn't a lot of room between the engine and hood. Second is that the engine compartment gets rather hot even as it is, especially in the pre-'77 unvented hoods. Insulation would make the problem worse.

If you have continuity from the (-) of the coil to the #1 of the ECU, voltage/ground to the ECU, and a firing ignition coil, the ECU should ground the injectors to fire them. Literally nothing else about your vehicle would have to be right. A quick tip: You can plug a christmas light bulb (miniature variety) into an injector connector to see if it flashes when you crank the engine (easier than listening for an injector click). It should flash longer/brighter if you disconnect the coolant temp sensor. I'll be very interested to know whether your ECU has died. Sometimes it seems the 1978 ECUs are particularly prone to drift. I've not yet heard of one going out, but it wouldn't completely surprise me. FAIW, I bought a spare '78 ECU for $20 off of ebay.

Fixing vacuum leaks is always a good idea, but you need to realize that will make your engine run richer, not leaner. A long, lingering fast idle is probably a fault with the air regulator. It's got an electric heater inside that could be out. This is a troublesome part with which I seem to have lots of trouble myself. (I'm on my second used part now, and both have stuck open. I guess I'll have to break down and buy a new one.) You're correct that the temp gauge and the EFI have different sensors, both of which are stuck in the front of the thermostat housing. The one-wire sensor is for your gauge, and the two-wire sensor is for the ECU. Note that the ECU's temp sensor and the thermotime switch are located right next to each other and have the same connector type. They will frequently get their plugs swapped. The thermotime switch (which has the larger body) should be connected to the plug that is wired in parallel with the cold start valve. If they're swapped, that could be the source of your high idle and rich running problem right there! I'm afraid I know nothing about the additional California stuff. No need for altitude sensors where I live. We're at sea level! Good luck tracking everything down!

Oh, finally, in '78 the cat was only required on California 280Z vehicles. If yours isn't specifically a California model, then you might be able to leave the thing off. Even if it is, it's quite possible nobody will know the difference. I've been asked about the absence of a cat on my '78 Z, and I simply explain that's how it was built. As I recall, the factory emissions sticker on the underside of my hood makes no mention of a cat.

Johnny, Wade's advice is spot-on for most modern vehicles, but our Z's are more primitive than he's giving them credit. With regard to the L-Jetronic system... There's no connection between the tachometer operation and the ECU. Both are fed by the same signal from the (-) of the ignition coil (which connects to the "S" terminal of the tach and the #1 pin on the ECU connector). However, the tach doesn't even need to be present in the car for the engine to run. (I know this for certain because my dash was missing its tach for a while.) The ECU gets all it needs from that signal to the #1 pin. It has its own circuits for determining engine speed. I'll also mention that the L-Jetronic ECU is completely analog and has no O2 sensor feedback, so your engine can only run in open loop mode -- the only operational mode this system has. As a result, your system might be running rich and not "know" it. To get your engine right, you have to make certain all the sensors are right, and you have to clear up any vacuum leaks. Even then, the ECU can drift in its calibration over the decades. These things tend to drift lean, especially on the '78 models, for some reason. (There are remedies for this that don't involve replacing the ECU.) If you're running rich (strong fumes), do check the TPS, but especially check the coolant temp sensor and its connections. That connector tends to get corroded and crumbly, and if the connection opens up, your engine can run incredibly rich. Also check for a stuck (open) cold start valve or a malfunctioning thermotime switch.

One more little note: We went to the dump today to dispose of a kapoot freezer. There in the metal recycling area, where they deal with discarded appliances, was a pile of exhausted 30 lb freon tanks of assorted varieties. These would of course be less prone to leakage than a 1 lb can with a can tap. I'll be evacuating one of them to store my left-over R134a. Anyway, all it would take is an ice chest and one of those tanks to set yourself up to reclaim freon from your system, be it R12, R134a, or whatever.

Hi all, Sorry to be such a stranger. Life gets in the way, I guess. Mostly I'm away from my computer, which makes me more productive, but less communicative. Anyway, I've been dealing with the 134a A/C on my Saturn (yes, I know, not a Z) and have some further ideas that might help people with their systems. First, I have to compare the performance of my '78 Z with exactly 2 pounds of R12 (per specifications), vs. my Saturn with an unknown quantity of R134a, which I just topped off. The Z blows ice cold , while the Saturn is pleasantly cool. I think the difference is that the charge on the Z is exact, while the charge on the Saturn is approximate. Although I can get a vague notion of freon levels from operating pressures, etc., I have to say that topping off a system seems to be more of an art than a science. From what I can glean from the Intenet and from various service manuals, nobody seems to commit to hard numbers and objective criteria for determining what is a full charge. The best criterion for a full charge on my saturn is the specified 1.5 lb of R134a that it takes, when charging from an evacuated state. So I'm left thinking the best way to service our A/C systems is not to top off, but rather to evacuate and then recharge. So how might one do this without fancy equipment, without venting (much) precious R12 to the atmosphere, and without violating the law? Here's how: First, you need an old freon can with the tap. If your system isn't cooling much, chances are that you have much less than one pound in your system -- enough to recapture into a 1 pound can. First evacuate your can with a vacuum pump. If this is not possible, then alternately let the can pressurize with freon from the L side, close off the L side, then vent the can out. Do this 3 times, and almost no atmospheric gasses will be present in the can (roughly 1/125 of what was there originally). Yes, this is venting freon to the atmosphere, but it's really no different than purging a line, and it doesn't really lose much freon. Sometimes you have to do what you have to do to get the air out! Now that you've got an empty can attached to your manifolds (either evacuated or full of freon gas) and the low-side hose attached to your A/C, open up the low-side valve to pressurize the can. Then place the can in an ice bath. Freon will immediately start condensing inside the can, creating a relative vacuum that will continue drawing freon across. You will eventually be able to fill the can with all of the liquid freon in your system. You'll know when you're done, because you will no longer hear the hiss of freon flowing into the can, and the system pressure will drop rapidly to approx 27 psig (for R12). This pressure is the vapor pressure of R12 at freezing (i.e. in the can). If you want to be even more thorough, collect the R12 when cooling the can with dry ice. Either way, only a trivial amount of freon will be left in your system. You may close off your can and set it aside for later use. Next, evacuate your system with a vacuum pump. This will rid your system of any air or moisture that might be present. Note: This is an optional step. Finally, you'll want to recharge your system. Unlike with most topping-off methods, you won't have to guess. Look up the specified capacity for your system (e.g. exactly 2 lb of R12 on a stock 1978 system), and put that amount in. You'll need to weigh your can before it is emptied back in the system and then after it is emptied. The difference, in pounds, is the charge you started with before reclaiming the freon with the can in the ice bath. Figure out how much additional freon you need, and then add it from a new can (using the scale). Don't overcharge. Stop when you've delivered the specified weight. What to do with the additional freon left in the can? That's an age-old issue. In my experience (and I think the experience of others), those can taps are a bit leaky, and you'll lose the freon over time. You can take the can to an A/C service center and donate the contents. (They should be grateful and not charge you for the donation. If not, go elsewhere.) ~or~ You can greatly reduce the pressure of the contents of the can, so that the rate of leakage isn't so severe. How? Just throw it in the freezer. The leakage rate would be cut to maybe 1/10 that at room temperature. Don't worry about any trace amounts of leaking freon in your fridge, BTW. It's inert. That's all. I just thought these tips would be useful. I didn't read them anywhere else and just had to invent the methods. Stay cool! Sarah

Ahhhhh, yes... Blue Bell ice cream.... You're making me homesick, Andrew! Wade, to be clear, I did use a vacuum pump (bonafide A/C service variety) to evacuate the system. I didn't replace the receiver/dryer, though, as I didn't have an open system. Total freon leakage has been about 2 lb since I've owned the car, so it's not like anything has been hissing. I also didn't add any goo products -- don't believe in them. FAIW, my A/C blows very cold now.

Steve, I mean the mineral oil. As I understand (note: I'm no A/C expert. I've just done some reading...) the ester oil is considered compatible with residual mineral oil when doing a 134a conversion, and it's of course very easy to find. However, that doesn't mean that the ester oil gets along optimally with the R12. I've been told technicians do add ester oil to R12 systems, but I simply erred on the side of caution and used the original variety of mineral oil. It was probably unnecessary to do so, but I always prefer using the original stuff, rather than something that's compatible with the original stuff.

Yeah, I could have used one of those! Harbor Freight? (I didn't look there.) The Colonial Parkway is great, but so are parts of Texas. Brenham in the springtime is one of my favorite drives. One particular drive through the Brenham area was the closest thing I've ever had to a religious experience.

I've tried that method too, Grant!

Congrats!! Wow, I sure am glad we don't have smog testing here in VA, not that my exhaust would be that awful. It sure must be a PITA!

IMO, the very easiest way is to pull off the hose between the fuel filter and fuel rail. Hold a rag around the hose as you pull it off. The rag will catch the spurt of fuel (about one tablespoon of it, give or take). Then throw the rag on your driveway to evaporate.

Update: I finally got more motivated with the warm weather, and my A/C is blowing cold again. I found the leak. The flare fitting on the high side of the evaporator coil (at the firewall) had gotten loose, so I tightened it (and also the low-side fitting). Now here's a clever way to reclaim your freon without a fancy freon reclaiming machine. You'll need an empty freon can that you've saved back: First, hook up your empty can to the center (yellow) hose of your manifold. Then evacuate it through either the high or low side line. Close your valves, and then hook up your H and L lines to the A/C. Purge the air from the lines at the manifold fitting. Then tighten the fittings, and open the valves. Now put the empty freon can in an ice bath to lower the vapor pressure. What's left of your freon will slowly condense into the can. This will take quite a while, but the operating principle is the same as that of a heat pipe. When you're finished, there will be no liquid freon left in your system. Obviously this won't work if you start with more than a pound of freon in your system. So with an empty system, I then evacuated, let stand for 30 min, and observed no change in vacuum. I then introduced 2 oz of mineral oil and dye. Here's some helpful info in that regard: R12 refrigerant oil (rather viscous, dehydrated mineral oil) is REALLY hard to find. There are mail order sources, and I suppose you could buy it with the requisite licenses at a refrigeration company, but there's still one source where everyday people can just go and buy the stuff locally -- NAPA. It's a stock item there. When I asked the guy at the counter for a bottle of the stuff, he said he didn't think he would have any, but he went into the back and surfaced with a dusty 1 qt. white plastic bottle that had turned yellow over the years. The total with tax was $10.15. Getting it into the system can also be challenging. In the good old days, we'd just buy a 2 oz can of the oil, loaded with a bit of R12, and shoot it in. You can do that with 134a, but not with R12. Our stuff just comes in a bottle. So what you do is use one of those precious empty freon cans that you've saves, patting yourself on the back that you're the sort of pack rat who never throws anything out. You cut it in half, making a cup with a fitting on the bottom. Pour in your oil, and suck it right into the evacuated system. The easiest way to do this is to evacuate via a hose directly from the pump to the low side. Then connect the high side hose to the manifold and the yellow line to the can. BTW, it flows slowly into the vacuum, being rather viscous. Now change around the fittings, evacuate again via the yellow line, and charge the system. You'll get just a bit of oil back into the vacuum pump. (Mine fluoresces yellow now!) FAIW, I think there's such thing as an oil syringe, but I couldn't find one. Anyway, with luck my system is now tight and will not leak my precious R12. And I'll be cruising the Colonial Parkway in cooooool comfort.

Jeff, usually parts from the same run are very much alike. I remember making very high precision voltage ladders out of +/- 5% resistors (not very precise). Because the part-to-part variability was more on the order of +/- 0.5%, they worked quite well. This is to say I would be surprised if injectors from the same batch would vary that much from each other. Finding a set of injectors with the right flow rate might be more difficult, though, as you indicate. Dunno...

Healey, the connectors offered in Zed's link look quite nice. I'd bite if I hadn't done my engine bay already. The eBay connectors are just a tad flimsy. That's not necessarily a bad thing, though. You can actually work them apart by twisting/deforming, rather than pulling off the wire clip. I suppose that's a lemon/lemonade argument. I can't remember whether there are bullet connectors in the harness. (I just made myself a new injector harness with a 12-pin disconnect.) However, I can tell you that connectors are always trouble, particularly on higher current circuits. If I were you, I'd crimp the connections and then sweeten them with solder. That would make them 1000% better than OEM. They'll last forever. You may need to use a bit of vinegar to clean corrosion/tarnish to get a good solder joint.

Healey, in all honesty, I forgot to mention that I still had fuel/air ratio issues I was dealing with when I overhauled the EFI. The engine didn't run much differently between the old configuration and the new, so I concluded the injectors were injecting roughly the same. I ultimately richened the mixture by lengthening the base pulse with a modification of the coolant temp sensor resistance. Anyway, these were roughly the same mix: Before: No major vacuum leaks. One minor leak between the intake and head near the #6. Original (1978?) OEM injectors. All components checked out fine. After: No vacuum leaks at all. New injectors. Everything cleaned up and pained pretty! Anyway, I can't promise you that my $25 injectors didn't inject a bit lean or rich. All I can say is that they weren't substantially different from the very old OEM ones. I *can* tell you that my injectors all flow about the same. I can't see any difference between cylinders in the plug reads. All read normal, now, with a delightful light mocha coloration.

The advice I got from a Z specialist was to stay away from the refurbished ones and go with new. He said it didn't really matter which new ones I selected, so I bought cheap ($155/set Standard Ignition off of ebay). They've worked fine so far (nearly 2 years as my daily driver).

I'm 5'7" and reach the pedals about right with the seat one notch back from all the way forward in my '78. In my old '75, the seat had to go all the way up. In this position, I have to duck somewhat to see the entire speedometer/odometer. I suspect the car was designed for a skinny person approx 6'4" in height -- lots of leg and relatively less torso.

Not a common problem, but funky wheels. When I bought a 75 Z in college, a shimmy problem drove me completely nuts. I finally swapped wheels with another Z, and the shimmy wasn't there. The problem? Off-center lug holes.

Here's how you achieve the same thing for free: If some guy is revving his engine, looking for a race, just give his car a look-over from front to back, if it's a nice one, give him a nod to compliment him, then draw a deep, relaxed breath, turn up your radio, and when the light turns green, don't race. Just be satisfied that your car is cooler than his, even though it might not be faster. 'Nuff said.

FAIW, Federal law prohibits the removal of (or tampering with) emissions equipment, and most of that would have come off with the EFI sytem. Here in VA, it's up to the inspection stations to know what is and isn't standard equipment on these cars, and very few inspectors know Z's that well. However, if they do, they will fail the car over the emissions equipment violation. This is in a state with no emissions testing. As long as you're not blowing smoke out the tailpipe, the content of your exhaust is of no concern to the inspectors. Of course here in VA, we also have the option of signing a statement that our antique cars meet state safety standards, rather than submitting to annual inspections, thereby circumventing the non-OEM emissions configuration issue. Anyway, I'm just pointing out that it can be a bit more complex -- usually isn't, but CAN be. BTW, if I recall correctly, NV is an emissions testing state, but an exemption is carved out for cars older than 25 years.

My local AZ got a couple of 5/8" EZ Coils in as samples. As they were cutting some 5/16" EFI hose for me, I saw the little boxes sitting on a shelf. Realizing how this would help me with my fuel hose bending issues (replacing all my vent/fuel lines), I pulled one out of its box and exclaimed, "Brilliant! How much are these?" They told me they didn't sell them, but that I could take them both if I wanted. They're made of stainless steel, BTW.

Use one of Goodyear's E-Z Coils. It works. You can also bend a piece of copper tubing and insert it into the hose

Duckman, I would sum up the differences between the 240 and 280 more in terms of functionality. The 240 is better as a sports car -- the sort of vehicle you fire up on weekends and go for spirited drives around twisty corners. It's also better as a collector car, because it will always return (somewhat) more value for your time/effort/investment. The 280 is a better daily driver. It's safer, more comfortable, more reliable, more environmentally friendly, and a bit easier on gas. The 280 is more of a GT than a true sports car. It is relatively comfortable on longer road trips. I don't hesitate to drive it longer distances. BTW, *everyone* disses the park bench bumpers! Geesh! However, I like them. They're emblematic of an era, and the floating front bumper actually contributes positively to the sleek lines of the car. I admit they're more appropriate for cruising in a cool GT than running twisties in a nimble sports car, but they have their place. (I'm not as fond of the rear bumper and have plans to pull mine in a bit.) I'm not saying everyone else is "wrong." I'm simply saying the bumpers *can* be loved!