Zed Head

Leon, you've corrected a statement I made in a different thread. I said 4% of the time (30 of 720 degrees) there was overlap, according to the cam specs. in the FSM, but I neglected the other 5 cylinders. 6 x 4% = 24%. Actually 6 x 4.2 = 25%. 25% is pretty good odds that there will be some leakage through the intake manifold to the exhaust. Of course, this assumes correct valve lash settings. Looser lash would reduce the odds. You should also consider blow-by past the rings and valve seals. Still a test worth doing if you're stuck.

There is something not quite right about the "solution" in Post #10. The thermotime sensor only controls the cold start valve, which is only powered when the key is at Start. So the thermotime sensor should have nothing to do with your backfiring problem. "Off-idle" leanness could be caused by the TPS not indicating "idle" to the ECU. According to the FSM, Engine Fuel section, there is an "after idle" enrichment. It appears this is added by the ECU when the TPS switch moves from idle to the middle or part-throttle position. The diagram is on Page EF-11.

If you get a filter with 1/2" barbs, everything would work correctly, right? The inlet on your fuel pump is probably 12 mm or 1/2" (depending on the pump). Have you compared the fuel pump inlet size to the fuel tank outlet? 1/2" from the tank (actually 12 mm probably), 1/2" to and from the filter, 1/2" inlet on the fuel pump. The outlet from the tank is the big one and the return line from the engine bay is the small one (5/16" or 8 mm).

This guy got 192 hp with carbs and fairly mild components. The results are shown in Post #41. http://forums.hybridz.org/index.php/topic/100267-green-machine-gets-a-new-motor/page__st__40

Nothing in your picture looks obviously like a "vent hose". To me anyway. If you mean the vent line from the gas tank to the charcoal canister, that line needs to be open.

Check out Post #6 in this thread - http://forums.hybridz.org/index.php/topic/103494-broken-studs-on-turbowhat-to-do/page__pid__969336#entry969336 If I ever need to drill out another manifold stud, I'll try to build something like it.

Under the dash at the end of the brake pedal. If you have flexible fingers, you can do it without removing anything, just loosening the lock nut. Lots of good pictures and a description of the procedure in the FSM, Brakes chapter. http://www.xenons30.com/reference.html If no one has messed with the brakes recently, it could be something else. More details about the recent history of the car would help. Good luck.

Sounds like you have the pedal adjusted too tight and it's keeping the pistons in the master cylinder from retracting all the way. The fluid gets hot and expands, putting pressure on the brake lines, cylinders and pistons, because the fluid can't get back in to the reservoir. Did you adjust the brake pedal recently? Loosen the rod going in to the master cylinder until there is some play between it and the brake pedal.

Did you fix your fuel pressure yet? One very important reason the propane test didn't work might be because there is no leak. You might be wasting your time. The a-wipe might have been right after all - "Some asswipe told me one time to open up a propane torch and wave it around for intake leaks, this is complete nonsense."

This topic is really more about how to interpret the FSMs. Which is a pretty interesting topic anyway. I don't that that you can determine "reason" from the FSMs. Fun to guess though. Food for thought - how is the fluid level determined and what should it be when climbing the Rockies? The same for descending. How long can you climb the Rockies before needing to turn around and back up the mountains to re-lube the dry parts or to let the foam subside? Do Zs in San Francisco suffer more lubrication related transmission problems than Zs in Illinois? If it was super-important, there would be a sight-glass or dipstick installed to verify correct fluid level range. Like in an engine,where it is super-important, but there is still a one quart safe range. Also, Nissan surely would have put one of those cartoon guys in the FSM, sticking his finger in the fill hole to check level. No cartoon guy - not that important. (p.s. I'm kidding)

You should measure and set the static timing, and confirm that the vacuum and mechanical advance of the distributor both work correctly. The later 280ZX distributors are designed to run with EGR and have a lot of vacuum advance. You might have to dial back the static timing to avoid knocking at partial throttle (where you'll be driving for economy). The first thing you should do is determine exactly what distributor you have and measure and set your static timing. The 79 ZX has a pretty good setup, the later ZXs get more complicated. What year did yours come from, or what is its part number? Your jumpy timing at idle could be because the vacuum advance vacuum hose is direct to the intake manifold instead of a ported source.

Probably dirty battery terminals. The engine is running on battery alone. Turning on the lights heats up the dirty terminals enough to break the connection - no current from battery or alternator, engine dies.

Don't' forget to clean your battery terminals when you have the battery out. Dirty terminals cause a lot of problems. I've known about terminals being a potential problem for many years, and I still came close to buying a new starter about a year ago, before I realized it might be the terminals, cleaned them up, and got back to normal.

When was the last time you looked under the boot? It could be a pool of oil that's taken years to build up in there. As the shaft moves back and forth maybe it's been moving a tiny amount of oil one way more than the other. The seals aren't perfect. Just a possibility. You might dry it out, drive it and see how fast it fills up. Count how many shifts you make so that you can determine an oil removal maintenance schedule! On the other hand, it's a good reason to take something apart that hasn't been messed with for a while.

It's described in the FSM, Engine Electrical section. I don't know where it is on the cars with ammeters. The L pin in the plug should show 12 volts when the key is turned on. If it doesn't, something's not connected right. The "warning lamp", wherever it is, should go on when the key is On but engine not running, and off when the alternator is charging. Edit - my slow typing got me again. Stevej, the FSM does show a "warning lamp" in the regulator circuit. Maybe they're using the brake check warning lamp for voltage? Either way, the L pin should have 12 volts, key On, engine not running.

http://www.classiczcars.com/forums/showthread.php?44115-Brake-Cylinder-Retaining-Shim&highlight=wheel+cylinder+clips

FW is right. Compost is the key word. Hey, regarding the yogurt cup leak down test: I had realized in the past there is one potential difficulty with the test. Overlap. The intake and exhaust valves are both open at the same time for just a few degrees at the end of the exhaust stroke, beginning of the intake stroke. For a stock cam, according to the cam card, it looks like 30 degrees out of 720, or about 4% of the time. A 4% chance that your intake will have a big leak right through a cylinder to the exhaust. So if you get a big leak, run the test again to be sure you're not sitting on the overlap.

Ben's Z might be on to something. I had an external water leak between the head and the block that would seal up when the engine got warm. The cooling system held pressure fine when hot, it just leaked a small amount of hot water while the engine was heating up and cooling down.

Edit - I wrote a most excellent reply here but decided not to fuel the compost pile and erased it. Your fuel pressure should be 36 psi. Your engine is running lean, assuming that your gauge is correct. You either have a supply blockage or a bad fuel pump. Get the fuel pressure up to 36 psi (test it with the vacuum hose to the regulator removed). The turbo engine will be more difficult to handle than what you have currently

The slot in the assembly is designed for the "plate-lock" (Nissan term, #63 here - http://www.carpartsmanual.com/datsunS30/DatsunZIndex/PowerTrain/TransmissionGears/5Speed/tabid/1708/Default.aspx.) It determines the orientation and the depth of the assembly. The later 5 speeds have a different assembly than the early 4 and 5 speeds. I have the 17 tooth gear in my transmission,with 3.54 rear gears and 205-70/14 tires (25.3" dia. by internet calculator), and my speedometer works perfectly. The same calculator shows your tire as 25.1", so the 17 tooth is probably as close as you'll get, IF you have 3.54 gears. http://www.1010tires.com/TireSizeCalculator.asp?action=submit Swapping gears looks pretty easy, a small roll pin just needs removing and replacing. Any stock 280Z with an R200 should have a 17 tooth gear, I think that they all came with 3.54 gears. I have 76 4 speed, 78 5 speed and 83 5 speed in the garage. I might be able to get a picture if you know what you're looking for. Here's a couple of links, that you may or may not have seen that might give you some ideas - http://www.geocities.com/inlinestroker/ratio.html Look down at the bottom of this page. http://home.comcast.net/~zheimsothtn/transmission3.htm Note - the picture in this link doesn't tell the whole story since there is actually an upper and lower lock plate orientation for early and late B type 5 speeds. It has good pictures though.

Does the Charge light turn on when you turn the key to On, before you start the engine? Sounds like the Lamp terminal is not connected to the Lamp wire from the harness. That wire provides the initial current to magnetize the alternator so it will start charging immediately. Find the wire from the Charge Lamp and connect it to the L terminal n the ZX alternator.

I got the ratios from the FSMs. Of course, they could be wrong. I thought it was odd also, but it's in there. The 3.36 R200 is an oddball also. I didn't realize that the turbo diffs had a different pinion flange. By similar reasoning as yours, why wouldn't they have the same pinion flange as the 280Z 3.54 long nose R200s? Seems odd. I tried to deduce pinion flange type by the pinion flange special tool described in the FSMs. The tool changed in 1984, and the turbo supplements I have don't show a different tool. Oh well, new knowledge. A few loose ends to tie up for garretthes, but overall not a tough job. Except for the pinion nut. Do you have recommendations on how to hold the pinion flange while removing or tightening the nut, if you don't have the Nissan special tool?

The ZXes had both available. They're shown in the FSMs, Prop and Diff section, all the way up to 1983. Anyway, I've been in the same boat with two 3.54 gear R200s. Swapped one for the other and they both sounded the same, even though one had fewer miles. One trick people do is to run 85-140W gear oil in place of the 75-90W or 90W spec. Lowers the volume of the whine.

The R180 is smaller and narrower and has a more square back cover, the R200 is more rounded and bigger. It's easy to tell if they're side by side, but difficult to describe. Compare the 83 to the 79 and it should be apparent, the 83 Turbo diff should definitely be an R200. There are pictures around the internet. Post a picture of yours and someone will be glad to identify it. I realized also that your 79 could have 3.36 rear gears. Still not the 3.54s that the turbo diff would have. If they are both R200, it's really not as complicated as it sounds. The stub axles and the CV shafts both use internal clips to hold them in, so they are designed to pop out with a dead blow hammer or a wedge against the housing. The speedo gear can be a little more difficult because you'll probably need to remove the roll pin to get the gear off. Still not a huge undertaking. Is the turbo an automatic? I'm not sure about the speedo gears from those, you might need to do some research on it, or find the right gear from a different manual trans car. Worn mounts can allow more vibration to enter the cabin. I don't know a bunch about ZX diff mounts though, they are different form the 280Z mounts.

I've seen P90A heads on non-turbo cars in the local wrecking yards. I don't know how they got there, or what pistons were in the F54 block, but the P79 and P90 heads have the same combustion chamber volume, so if you have flat top pistons, you would be around 8.8 CR, like the stock NA F54/P79 setup. As LeonV suggests, check through the spark plug hole with a strong light to see what you have.