Zed Head

It might be that your injectors aren't firing on every revolution like they're supposed to. That could be an ECU problem. Make sure that injectors have a 12.6 volts at the connector pins with the key On. Ideally, you would also measure voltage when running to verify current flow but that would take some ingenuity. It should drop to ~9 volts due to the dropping resistors and the injector load when running from what I've read. Edit - I just looked back at your post and see that you've already been in the ECU. For what it's worth I had a bad ECU but could find no visible signs that it was bad. I'm pretty sure that the FSM says if you've checked everything and still have a problem, it must be the ECU. Not a very satisfying way to solve a problem though. I've seen several stories about people kicking or bumping their ECUs to fix a problem. Usually they were fixing a rich condition though. Edit 2 - Did you find water in the area of the ECU after the car wash? Has it been getting the occasional watering over the years? You might check the ground circuit to the ECU also. The ECU has to have a good ground to fire the injectors. You might have rusty ground points.

Thought this might be interesting to some as far as gauging the 240Z's current popularity. I had thought about going to this auction to see if I could "steal" a 240Z for under $1,000. The car and auction were on Craigslist for about 5 days before it sold. It was correctly identified as a 240Z, not an SX, on CL. The link should last, they have all of their old auctions up. https://speedstowingauction.auctionserver.net/view-auctions/catalog/id/28/lot/5806/

I installed my plug wires in backward rotation once (clockwise instead of counter) and the engine started and ran, very poorly. Confusing and it took me a short while to figure it out.

Your symptoms pop up occasionally and there are varying opinions on how to confirm the solution before replacing parts. It's a dilemma. In my own personal case, my engine had the same sort of symptoms as yours and I too tested everything and ended up replacing the AFM, which showed as out-of-spec. The rebuilt AFM was the solution for me, but not quite so for others, see here (http://www.classiczcars.com/forums/showthread.php?40392-76-280Z-Question-on-dist-manifold-vacuum-dist-timing-fuel-pressure-brake-booster&highlight=jennys280z) Cozye and FW have had success with modifying the water temperature circuit, but their problems were minor compared to what I think you're describing. When my AFM was bad, the car was barely drivable, and very embarrassing to be in on the road. The AFMs for 1975 - 1978 are essentially the same except for the fuel pump cutoff switch, which 1978 does not use. If you could borrow one, you might be able to get a cheap diagnosis, beyond measuring resistance on the AFM circuits.

How much have you actually driven the car since Post #1? How much driving after all of the changes, but before the ZX fuel rail? I read through the thread and it looks like all of the work has been in the garage. It may be that you've been focusing on the wrong thing, or that you had two problems and now you just have one.

Have you checked the condenser/capacitor for proper function? Maybe it is wearing out, has turned in to a resistor and is hindering your coil charging. As I understand things they usually die completely but if the dielectric material started to break down it might leak current slowly. Many multimeters have a capacitance measurement function, but at the least the condenser should show infinite resistance. FWIW, I have a condenser on my negative post but only for noise reduction to the tachomoter. I installed a Z31 coil and my tachometer stopped reading correctly, until I added the capacitor. I put it on the negative side because that's the side the tachometer sees. But that's another story, my point is that I have a condenser on my coil (-) post and everything works fine. This is a 280Z with the stock ECU , GM HEI module and a Z31 coil.

The old u-joint bearing cup should not have fallen out when the retaining clip was removed. It should be a very tight press fit and should have been difficult to remove. Your driveshaft yoke may have been messed with or is just worn out. A salvage yard replacement driveshaft might be in order.

This is one of those frustrating reports where you don't know if the added performance equipment is very good, or the replaced equipment was very bad. No offense oz, I've enjoyed reading your comments over the time I've been around this forum. But is there any way to compare the Cedric's 2.8 L engine exhaust components to a 1978 280Z's, for example, for the Z crowd? Without knowing what you started with, there's no way to measure the benefits for the rest of us. Do you still have them, and could take a look and a measurement or two? Since 1978, who knows what previous owners have done to the exhaust system. My exhaust pipe was smashed to half-diameter from a misplaced floor jack. Your report goes against the bulk of what I've read, so it's some interesting stuff, considering the ease of getting it done. edit - To be clear - 23% from an exhaust system modification is an enormous gain! That's why I'd really like to know more. I have never heard that the stock Z exhaust was that bad.

I mis-wrote in my previous post. A 280Z distributor would give the VR, that would work with the GM HEI module, and more stock appearance without the big box of the ZX on the side. My 280Z has an inline capacitor that runs back to ground at the distributor. I don't know where the other end goes. Otherwise the coil does not have one attached to either post, and nothing is shown in the wiring diagram for the ignition circuit. I think that for EMF noise reduction the capacitor just needs to be attached to the line that's being protected from the noise. But I don't think that the electronic ignition coil uses one because the "dwell" and coil charging is controlled by the ignition module. And I just took a quick look at the ignition circuit in the Engine Electrical section for 1972 (because I need to know now) and it shows the condenser connected to coil (-) along with the points.

Clutch problems definitely. Have you popped the rubber cap off of the slave cylinder to see if it's leaking? It will hold quite a bit of fluid. It sounds like it or your master cylinder might be going bad. The clutch line will almost bleed itself through gravity when the bleeder on the slave cylinder is opened.

I have seen where people have attached the HEI module to the bottom of the distributor. Maybe this is an option for retaining the stock appearance, but getting the advantages of electronic ignition. It would require a ZX distributor with a VR, but might be worth the effort. The more I read of the HEI module's design and function, the more impressed I am. They really packed a lot of function and durability in to a small, simple package.

Thanks, I re-read the post and extracted the same. I don't mean to wee in the punch bowl but, having some background in the scientific method, I have to wonder if it is the headers or the bigger exhaust. All that I have read implies that the stock cast steel exhaust manifold of the 280Z L28 flows very well. Still, the results support that the stock exhaust system of this unknown Datsun is restrictive. What kind and year of Datsun is it?

The bleed valves should be at the top. If not, swap them, you'll never get the air out otherwise, no matter how many times you try. I would do this first, if they are on the bottom, and then bleed just the fronts. You might already have all of the air bled out except for the two air pockets in the calipers.

Are the bleed valves at the top of the calipers? It is possible (and easy) to install the calipers on the wrong sides of the car. This puts the bleed valve at the bottom, leaving a big air bubble that can not be removed by normal bleeding procedures. I've also seen similar symptoms from people who had the reaction disc in the brake booster fall out, but I don't know much about that problem.

I read both of your posts and can't figure out the conditions for the three pulls. You mentioned a single carb, a four-barrel, a ZXT distributor and headers but didn't really identify the combinations used. Could you describe the setup for each pull?

What car? Have you checked the FSM, the ignition system wiring is well-illustrated and described.

You should see the reluctor move. The breaker plate, the plate that has the reluctor (or magnetic pickup coil) mounted on it, is the part that moves. Another way to check it is to remove the screw that holds the vacuum advance module to the housing and slide the module out a little bit, pulling on the breaker plate, which is what the vacuum module does in operation. You will see the breaker plate move and can get a feel for how messed up it is. Don't move it too far or the bearings might fall out. It should move easily back and forth with no gritty feel. Look closely at the edges of the breaker plate for visible ball bearings. What happens is that the thin plastic locater for the bearings breaks and lets the bearings push out under the pressure of the breaker plate mounting assembly. Or maybe they get rusty and then the locater breaks. Either way, no more vacuum advance.

I've seen it described around the internet, and pretty sure I saw it at Hybridz along with some non-Nissan options for seals. Search 240Z, 260Z or 280Z and valve seal and you'll probably find some write-ups. It involves some rope or hose or air pressure to keep the valves up and a couple of tricks to get the seals on without cutting the edges.

I'm using BWD injectors with no issues. Getting ~20-21 mpg avg. now. I got them at Schucks/O'Reilly. I got the cheap $40 ones, but now they have another BWD type for $77. Remanufactured. The remans cost $77, the new ones $40. So your $59 for cleaned and re-hosed is in the middle. 10 - 12 mpg is pretty low. Have you checked your fuel pressure and water temperature sensor resistance? Make sure you check fuel pressure with the engine running also to verify that the pressure drops with intake vacuum. My regulator went bad and mileage dropped to 15 mpg and the car really stunk. Are you actually calculating mileage or just guessing? At 10 mpg I would expect liquid gasoline to be dripping from your exhaust pipe.

Check the vacuum hose from the intake manifold to your fuel pressure regulator. Fuel pressure should be ~30 psi or lower at idle, depending on intake vacuum. You'll run a little rich and gassy without it connected.

Funny, I almost added a comment about the racer types who believe mastering the engine via throttle and clutch control is all that's necessary. Behave beast! The dash pot is a luxury and it does allow easier shifting. Call me lazy. I can take it.

I knew I has seen a thread on this out there somewhere. I just adjusted mine in a turn a few days ago, to give a more consistent feel during shifting. At certain times during warmup, the revs drop faster than usual, causing a "clunky" shift. I've adjusted it in the past to avoid the engine dieing problem kjp... mentioned, but I added a little more fine-tuning for driveability. I think that there is a factory spec. on where it should be, but with my worn engine and throttle parts, I just adjust until it does what I want it to do. It seems to have made a difference, I can't remember a clunky shift since doing it and I can see the tach moving down more slowly. If you can find a pot with a similar form you might be able to rig it onto the bracket. The bracket keeps it centered over the throttle lever. It's just a spring and leaky diaphragm gizmo.

To complicate things even more, most cars use a ported source for vacuum advance. So as soon as you touch the throttle, you're timing advance jumps significantly. Plus mechanical advance which kicks in at 600 rpm. You can be around 30 degrees advance at low RPM, steady cruising conditions, above 2500 RPM you can be in the 40s. And don't forget the idle air adjustment. Idle conditions are their own little world. Not to put a damper on playing with these things, just saying that there are a lot of other considerations. What happens at idle only gets you so far.

I can hear it but it's just a smooth "whir", no racket. I insulated the mounting points with some thin rubber sheet to keep it a little quieter inside. I can barely hear it from outside the car. It sounds like I imagine a good pump should sound. If the "racket" is an erratic, grinding noise maybe you do have a bad one.

June bugs. I remember those guys. They're the big ones, like giant Japanese beetles. Don't have them in the PNW. For what it's worth, I have had an Airtex E8312 (the high pressure FI pump) in my car for 1.5 years and have had no problems. Bought it new at Schucks. Have you pinched the return line to see if pressure rises? It might give you more clues on fuel flow versus weak pump. You can break these problems in to pieces and get to a point where you're more certain what to fix. Edit - changed some stuff.