FastWoman

Yeah, it might be warped or corroded. That old '77 Chrysler Marine 318 I have in my boat is giving me this headache. Unfortunately the problem is on the mating surface of the head, not the manifold, or else I'd just have it milled.

Hi Gary, Download the FSM for your car at www.xenons30.com. It's free, put out there for the collective karma. In all likelihood, there are many things wrong with your engine, so trying to diagnose it can be an exercise in frustration. My advice would be to just go through it from end to end, check every component and every connection, fix whatever you find that needs fixing, and you'll end up with a running engine. There will be one final component which might pass Nissan's diagnostics, but which might still be out of whack. That's the ECU (the "computer"), which Cozye and I have found can drift in its calibrations over time. (It's analog, not digital). There are remedies for that too, as you'll find in the "purs like a kitten" thread. Eventually you'll get there, and once you're done, you'll understand every part of the EFI and realize it's not so complicated after all. (To me, CARBURETORS are complicated, as they depend somehow on magic!)

I don't know if your '76 is configured like my '78, but it's not necessary (in my year) for the magnet valve to work. In fact of my two magnet valves, the only one that works is the one that actuates the high idle for the AC. A problem that I did have on my '78 was a gummed up and leaky mode selector vacuum switch. That might be your problem. For more info, see a thread I started here: http://www.classiczcars.com/forums/showthread.php?35521-Refurbishing-the-HVAC-vacuum-selector-valve-in-a-1978-280Z-useful-info&highlight=

To be truthful, there are a few adjustments on the AFM, but they're not meant to be adjusted. That doesn't mean someone hasen't adjusted them. Go to the Atlantic Z website (google it), and visit their tech tips (?) section. You'll find articles there about checking/adjusting the AFM. Before you do that, though, check your coolant temperature sensor circuit. If the sensor is bad, or if the connection to it is bad, your engine can run SUPER-rich, with black smoke out the exhaust. The best place to check this circuit is at the big connector to the ECU, behind the driver-side kick panel. This measurement and many others are described in Nissan's Factory Service Manual for your year/model, which can be downloaded for free from www.xenons30.com. BTW, welcome!

I have an old Chrysler Marine 318 that measures about 95 psi compression on all 8 cylinders, using the same compression gauge that measures my Z at 180. The 318 runs fine, except for an exhaust riser that I can't seem to get to seal correctly against the head. It might be a combination of low compression and a bad gauge.

Welcome, Orange, from another '78 owner! :-)

Jan, the air temp sensor has relatively little influence on mixture and absolutely no influence on the CSV circuit. The CTS has the most influence on mixture (but still no interaction with the CSV). As Eric says, the CSV is only switched on for temps below some threshold temp somewhere in the 50's.

Weird... What happens if you disconnect the reverse switch? If the problem goes away, it might be some sort of weird short. Do the reverse lights shine brightly, or are they very dim? Is it possible your clutch isn't fully disengaging? Hey, welcome to the community, Raul! :-)

Jan, I don't know the appropriate terminals for the '76 (probably the same as for my '78), but you can unplug the big connector from the ECU and measure resistance across the CTS and all its wiring right there. If there's a problem, that's where you'll be able to see it. Check your FSM for the correct terminal numbers.

Didn't know that about Craftsman. Mine were all purchased long, long ago. They still look perfect. I've busted one socket and lost one other. A few of my crescents and pliers have surface rust. All in all, though, I couldn't be happier with them.

I would normally agree with Cozye -- probably an exhaust leak at the manifold/head junction. However, if you're SURE you don't have a leak there, it might be a sticking valve or rocker that gets popped shut when there's detonation in the cylinder. You can try using a motor flush like Gunk. Only do this if there aren't heavy crusty deposits in your engine. Gunk is a great way to flush away the varnish and get your valves moving freely. You might also need to SeaFoam your intake.

The problem comes when you order the correct part and find that further instructions/guidance are necessary. For instance, I ordered an EGR valve, and it came with a bag of three dozen orifice washers and a printout matching part number with the correct orifice washer. As I didn't have the part number, I called to ask what it would be for my car -- i.e. which washer to install. I might as well have been speaking Swahili. The info was of course available, but I had to spend much more time finding it than I had hoped. I vowed to order from MSA next time around. PS Congrats, Arne! I hope you got your price!

Craftsman -- Sears' brand, also available at K-Mart (which Sears owns). Nice hand tools. They've always been very serious about their warranties. If you can manage to break it, they'll replace it.

Don't forget to take apart the emergency brake mechanism, clean it up, and get all the parts to move freely. Mine was rusted solid, apparently from nonuse. (I always park my car in gear with the e-brake off.) Strangely, my e-brakes acutally worked in this state, but not as well as they work now.

If you want to create something truly fascinating, how about putting a huge flywheel on the engine and making it a one-cylinder hit-and-miss engine? You'll need to make a few parts, but when you're done, you'll have an engine that can turn at extremely low RPMs and will go "chug/poof/wagawagawagawagawaga..waga...waga.....waga.....waga.... chug/poof/wagawaga..waga.waga..waga"

I used to use Gunk motor flush periodically on my '75 Z from long ago. I did this from 80k to 120k miles, when I sold the car. I gave my 168k 1978 Z one flush with Gunk, and it worked fine. The only problem (and the major difference between the two cars) is that my old '75 had occasional varnish (nothing unusual), while my more recently owned '78 looked like a caked up BBQ grill under the valve cover. I honestly didn't know it was that bad, or I wouldn't have so casually done the flush. When you liberate that much crap in the engine, you can block up oil passages and filter screens. Fortunately I had no problems. Also there were no oil leakage/burning problems with any engine I've ever flushed. I've done this many times -- 2 280Zs, a BMW Z3, a Saturn SL2, a '66 Mustang, an '87 Ford Crown Vic, and a '94 Ford Taurus. I've heard of alternative flushes, such as 1 qt of ATF, 1 qt of kerosine, and a couple of qts of diesel (never heard of a full crank case of the stuff). I've heard of no issues with those. The Gunk motor flush has high volatiles that cut the varnish pretty aggressively, unlike these other methods, but they all work. For my BBQ grill engine, I've been running a diesel formulation of motor oil -- Chevron Delo, which is very high in detergent and also high in zinc. It's actually a very good/appropriate formulation for our Z engines. The Delo has slowly been cleaning up the remaining crap from my engine, which now looks fairly clean. I've also used an excellent detergent additive called Rislone. However, I think the Delo works better.

I could be wrong, but momentary lapses in running are most likely due to a bad connection somewhere -- maybe your ignition. It's unfortunate that these intermittent problems are so hard to track down. I fear you're going to have to put up with the hiccups until the car dies and stays dead. Then you might have a chance of diagnosing it. Until that happens, I'd carry an emergency diagnostic kit with you for testing on the side of the road (or hopefully in a parking lot) somewhere. Carry some starter fluid to spray into the intake. If the engine will fire and then die on a good shot of starter fluid in the intake, then the problem is fuel related. If you can't get it to fire and die, then it's probably ignition related. Alternatively your entire system might be dead. Check for power to the (+) terminal of the ignition coil with a multimeter. Also go through your fuse box to see which circuits have power and which don't. So I guess that's your emergency diagnostic kit -- a multimeter and a can of starter fluid. Good luck!

I think it's hard to say from the pics. The driver door looks rusted out. The hood has lots of surface rust but might be OK. It's going to take a Bobcat to excavate all the dirt on the car, but it should provide a few inches of good topsoil for some lucky person's lawn.

A trick to remember firing order: 15 is too young. 36 is too old. 24 is just right. Or the 180 deg turned version for old folks like me: 62 is too old. 41 is too young. 53 is just right.

Ronaldo, when your crank is at TDC and your distributor is pointed towards #1, are your #1 cam lobes pointing up or down? Look through your oil filler hole with a flashlight to see. Also, can you confirm that your firing order is not backwards? Crank the engine to see which way the distribor rotor rotates, and then confirm that the order from #1 is 153624 and not 142635.

Well, there is this resource: http://www.kshoseclamp.com/wire_clamps.htm Clamps from 11 to 110 mm dia. I don't think it's possible to place a small order, though.

This will probably sound horrible, but... It might be possible to make some. It looks like a simple enough design. One threaded hole, two unthreaded holes, a screw with a ground-down tip, a washer, and a bent-up wire. Yellow zinc plating to complete it. I've seen this style of clamp still used for intake boots, e.g. on my '92 Saturn (which I suppose is not really a modern car anymore, although I bought it new). It wouldn't surprise me if someone still makes them.

Wow, this man has my respect!

No, not meaning to be cruel! However, I don't think you got an official welcome. WELCOME to the community! You can collect your Welcome Wagon gift at www.xenons30.com. There's a free download of the '76 Datsun 280Z Factory Service Manual waiting there for you. (The truth: It's always there for anyone, but consider it your "welcome gift.") This is the single most important source of information you can find on your car. Parts of it are also somewhat of an interesting read, in a car-geeky sort of way.

There's a slightly off-center notch on the linkage between the distributor and oil pump that supposedly ensures correct alignment, but I've read it's sometimes possible to turn the distributor 180 deg and still fit it into the notch. Maybe that's your situation. One more thing for the OP to consider: The #1 plug might be lined up with the engine at TDC, but are the other 5 plugs in the right firing order from there? Maybe it's backwards? This is a common error.