Zed Head

The battery gauge wouldn't really indicate a slight overcharge. It's not very accurate. And the older external voltage regulators can put out up to 15.75 volts, which is high by today's normal range of 13.8 - 14.3 for an internally regulated alternator (pulled these from a rebuilt alt. install sheet). Do you have any numbers? Your mechanic may not be familiar with the older regulators. The temp. gauge is also not very accurate and shares its voltage supply with the oil pressure gauge. The high number might just be an artifact. Is your mechanic suggesting an internally regulated alternator with solid-sate regulator or an external solid-state regulator? You can still get the external regulators. Might be the easiest fix, if you do have a regulation problem. But you need the voltage numbers first.

Send a message to superlen, he's been deep in to the ECU functions. He's building a standalone engine management system to replace the Z EFI. And the ECU is really easy to take apart. Maybe you'll find a shorted or corroded circuit. I've seen some crusty ECU internals, they live in a spot that gets moist if there's a windshield leak.

I guess I read it the way I thought showed that the TPS would be the culprit. Sorry about that, looking back I did read it wrong. Bummer then, problem not solved. It's odd though, that disconnecting the TPS removes the problem. That doesn't fit with the ECU being bad. Going back to what FastWoman suggested, when you say open, do you mean infinite resistance? Do you have a high quality meter that shows infiinty, or are you using a test probe with a beep? It might be that there's enough conductivity to trip the ECU's idle circuit, bit not enough to show on your probe.

30 psi at idle when cold is in the right range. Since your problem happens when warm you need to do the same thing when it's warm and you have 20 psi, which is not in the right range, it's too low. The cold test just shows that everything is working right when cold.

I guess I'll keep harping on the TPS. This is not right - open when accelerator is depressed all the way to full throttle I don't know if you can see the picture I attached in my last post, or if you haven't seen that page in the FSM. Pin 2 should show continuity at idle then OPEN when the throttle is just off-idle - 4 degrees is barely cracked open. Basically, when you crack the throttle, Pin 2 shows NO MORE IDLE. What you're writing is that the ECU sees IDLE all the way up to full throttle. That's what I've been proposing. Plus the fact that you don't see the cut with the TPS unplugged supports that it's the IDLE circuit continuity (Pin 2) causing the fuel cut. There appears to be something wrong with the TPS signal to the ECU, not the ECU itself.

The power break-up is because the fuel mix is lean. You should be at ~28 with the hose connected and 36 without. Did you get an adjustable regulator? It may have slipped adjustment or was never set right. If you have the stock regulator, pinch the return hose when the pressure is at 20 and see if it rises to 36 or greater. this will tell you if the pump can supply the pressure. Be careful, the aftermarket pumps will hit 90 psi and can cause leakage. If you think it might be the pump, you can prop the AFM door open with the key On, as Blue suggests in another thread, and just let the pump run while watching the gauge. Several people have had pumps that fail when warm. If the pump is bad, eventually it will start making funny noises and pressure will drop. I had one of those.

I was just looking at a used car, and the guy had just bought so knew little about it. It was in bad shape though, with an off-year AFM zip-tied in place and general poor maintenance. Someone had messed with it. The hole seemed to fit the general condition of the car.

Oddly, that picture shows up on a Ukraine web site also. Is there more to Blue than we know? The page translates to "How to Draw a Hut".

Interesting clue. But that's not supposed to happen either. The pump should only run when either the alternator is spinning or the oil pressure switch is activated, with the key On. That's what the pump control relay is doing. You're getting closer though. On looking at the relays - I think it might be easiest to just unbolt the complete relay bracket to get to the relays. I seem to recall trying to get to them form underneath and it's a pain. Don't forget to disconnect the battery first in case you have exposed wires. There might also be a fuse on the pump circuit that could have blown if you have a shorted relay or wires.

I saw a similar hole in the side of the engine of a Z I looked at last year. The guy said he din't notice anything odd, he was just driving down the freeway and the engine stopped. Are you going to pull the head? I'm curious about valve damage if a piston got pushed back up the cylinder after its cap came off.

A common noise for the Nissan transmissions is the countershaft bearing. When you disengage the engine from the transmission by pressing the clutch pedal, the bearing stops spinning. The banging could be a bearing with some balls missing. You might want to get in there before it fails completely. It's under the transmission front cover so you'll be able to get to it easily once the transmission is out.

Have you checked for power at the injector connections? You should have 12 volts on each pin in the connector. That's the first thing you should do. No power, no injector open.

Expanding on FastWoman's point - you're not reporting "no continuity" or open circuit at 4 degrees + off idle. You should see the idle circuit go open when the throttle blade is moved (looks like Pins 2 and 18). You might need a good meter to be sure that there is not some slight conductivity that would "trip the logic" as she suggests. In the same vein, I assume that the ECU TPS idle circuit monitoring itself could be bad. But I've never seen anyone report that. Still, the observations at 2800 and 3200 RPM should tell if any of this is even worth following up on.

That was probably my relay. Could you separate out the problems that are there when it was running, and the problems that are there now? Looks like you have everything blended together. The odd one is that the starter will turn the engine,which means the solenoid wire is getting power, but the fuel pump does not have power (this should be confirmed). That could be the fuel pump control relay or the pump relay itself. Try unplugging the small yellow wire from the starter then turn the key to Start and make sure that the fuel pump does not run. You can see in the attached diagram that the Fuel Pump Control relay gets power from the Start circuit first and powers up the Fuel Pump relay itself. If the pump is not getting power, make sure that your car actually has these two relays. Some of the 1978 cars still have the combined EFI and Fuel Pump relay, but may still also have the Fuel Pump Control relay to power it. I had a 78 with the combined relay. I think, that a failed Fuel Pump Control relay might explain some of your symptoms, like the back feed through the alternator charge light, since the L wire runs through it. There are others with better electrical knowledge on the forum. Yeah, it's complicated. Unplug that yellow wire at the starter solenoid and make sure the pump does not get power. That's what I would do first.

Watch your oil pressure with the low RPM. It sounds cool but these engines will eat a camshaft, especially the aftermarket ones.

I like having a right side mirror. It helps. The mirrors that make objects "closer than they appear" are better for the passenger side. Wider angle.

Your theory looks right. When disconnected, no idle enrichment and no full throttle enrichment. Mileage would only get better if you spent a lot of time at full throttle, I assume. When the TPS gets wet, the idle circuit shorts, apparently, then when RPM go above 3200, the ECU cuts fuel because it thinks you've just shut throttle. Obviously, the algorithm doesn't consider that 3200 RPM could be reached with the throttle closed.

I thought that some of the carb guys would have responded to your post but maybe they were thrown by the title and its reference to 1976 and a check valve. That's EFI stuff. I don't think that you need a check valve with carbs. The float bowls hold enough fuel to get the engine started, then the pump refills them. I would start another thread, with a good title, about the fuel lines to and from the carbs. People open threads that look interesting to them and "280Z fuel pump check valve" is boring to carb guys. Put the word "carbs" in the title. I only opened your thread because I have a 1976 280Z. If it said carbs I probably would not have (no offense to the carb guys).

I've never really understood why water in the TPS would cause the problem that it does but I think I have it figured out now, thanks to this thread. I attached the relevant passage from the FSM. Water in the TPS apparently makes the ECU think the throttle is closed. Details in attachment. One way to get a better idea of if it's the TPS is to watch the tachometer and note the RPM, when the cut out happens, and when it bucks. The tachometers aren't known to be super accurate so you may not see exactly 2800 and 3200 RPM, but if it happens consistently around those numbers, that would be a good indicator. If that's not it, then the old fuel pressure gauge poking out of the hood plan would let you know that you're maintaining fuel pressure. If you have proper pressure but it still cuts out, then electrical has more potential.

I've found that setting everything to stock specs., timing mostly, and running the idle air screw out as far as you can without inducing a miss, will get me through the Oregon DEQ tests. Timing advance and retard changes the ratio of combustion byproducts that they test for. It's probably why idle has a whole set of parameters tied to it, like initial timing, idle enrichment fuel, idle air bypass, etc. Air fuel ratio and timing both change immediately as soon as you open the throttle.

You might already be running 10% or more ethanol, from the pump. Denatured alcohol is just ethanol with impurities left in or added, so that you can't drink it. Benzene or some small amount of chemicals used during purification are typical.

Ignore everything that I wrote. You're working with a very different engine management system. I would go over to Hybridz and repost, with "Need help with Wolf ECU on modified turbo engine" in the title, and all of these specs. listed. Edit - I realized that there are two Wolf companies - Wolf engine management (the one Ron Tyler repped) and Jim Wolf modified stock systems. You have Jim wolf's modified stock system, so the FSM procedures are probably still important. BUT - I don't think that the Jim Wolf modified stock systems are designed for modified engines. They're designed to change the performance of stock engines. You might not be able to get that collection of parts to work with your engine management system. Saw your post on Hybrids - you should change the title to Jim Wolf modified stock ECU.

If I had a stock system and was looking to buy new injectors, I would get Standard brand, either the FJ3 or FJ707T. (Rockauto has good deals. Data is sparse but they might be better for heat soak than others. Before you buy though, since you're going to take things apart, you might leave the injectors connected to the rail when you remove them (they'll come out as an assembly), reconnect or leave connected the fuel hose and electrical and squirt in to some containers for a short time ( use small coke bottles). You'll get an idea of how unbalanced the injectors are. Do it outside though, with a breeze and no open flames. You should notice if #5 is totally dead. The engine will run a little rough and the spark plug would be dry or oily, but different from the others.

It's not how long the engine has run, but how much current is running through the module that heats it up. High RPM passes more current through the sensitive parts as it generates more sparks. High RPM, heat, weird behavior, turn off engine, cool down, back to normal.

You never said which turbo engine management system that you're using, but I assumed 1983 280ZX turbo since you said 24 degrees timing spec. Your sig says 1972 240Z, so you're probably working with a turbo swap in to an older car. Now you have a different TPS. What exactly are you working with? Did you test the TPS circuit at the ECCS plug, or at the TPS itself. It's always best to test at the plug first so that you know what the information the ECCS or ECU is getting.