78 280Z - no injector pulse

[Virto]

I'm starting this thread as a bit of a placeholder, moving this issue out of my old exhaust manifold/status thread since it's likely I'll need help.

The background is listed in the exhaust thread, so I'll keep it focused on the EFI here. Bottom line, car hasn't run in a year, head was pulled and tanked, and the car is back together now. The car will crank easily but not fire. Injectors show 12V but no pulse via NOID light.

Zed Head has helped give me some places to start - I'll likely only have access to the car over the weekend, so I can't just run out and mess around, as much as I'd like to.

I'll add to this thread as time goes on with status and results. If anyone else has any questions or direction (/wave FastWoman, ) I welcome your input.

[Captain Obvious]

You got sparks at the plugs?

[FastWoman]

Hey Kelly,

Good question from Captain! No sparks means no triggering of the ECU.

You also need connectivity from the negative side of the coil to the #1 terminal on the ECU to sequence it. You've got 12V at the injectors, which means you've got continuity through the drop resistors. All that's left is for the ECU to ground the injectors.

Got power to the ECU, BTW?

[Virto]

ZH mentioned checking for spark and also mentioned the coil to pin 1 connection (blue wire, I believe). I was told that it had spark, but I'll verify for myself when I get over to look at it.

I'll check to see if there's a break in the connection from the coil, as well.

I would *assume* there's power to the ECU, but I can't be entirely sure until I go over there. I'll have to pull out the EFI bible and see what pins on the harness I need to check for power.

Thanks, you two. I'm making a little list - it helps, really.

[FastWoman]

No problem...

Obviously check that the ECU has a good ground also!

[Virto]

The ECU grounds via the harness, correct? Not the case being mounted to the body.

The EFI bible says to test pins 5, 16, 17 and 35 for continuity to ground. Not sure if there were any changes in pin-out from 75 (last revision date) to 78, when the car was built.

[Zed Head]

There is a second version of the "Bible" (New Testament?) published for 1980 that has all models covered. It's a little harder to work with because there are so many choices, but it will have specific tests for your 1978 car.

XenonS130 - S130 Reference

Yes, the EFI system ground wire is that black one that has its own connection to the battery negative terminal. It may be extra but you can't have too many.

[Virto]

Very cool, thanks - I had no idea there was a newer version.

This one seems to have a few more tests that can be run and it's generally more well-written and clear as to what you're looking for and why.

[Virto]

Mmk, minor update - the car has spark for sure - it'll run on starter fluid, there's just no fuel coming in since the injectors aren't firing.

Spoke with the garage owner and let him know I'd swing by on Saturday to test the ECU and see what I can find - turns out the city just updated codes and notified him this week. If anyone is caught working on a car in the parking lot (ie, not a garage bay) it's punishable by a fine/court appearance. Makes no sense to me, but Elgin is super-big right now on making everything look nice and shiny to attract more well-to-do homebuyers. So I'll be the somewhat cripped, super fat guy sitting on the pavement out of sight trying to multimeter my ECU, .

So, with spark confirmed, is there anything we can rule out?

[Zed Head]

Make sure that there is 12 volts on each pin of the injector connectors, removed from the injector, with the key On. It will seem weird from an Electricity 101 perspective, but one side is power and the other side is the transistor circuit. Probably a pull-up circuit of some kind (unresolved in other threads). Both pins in each connector will show voltage if the ECU has power and things are correct.

If you have that, then check that Pin 1 has continuity (zero or almost zero resistance) to the coil negative. Make sure that the tachometer is connected. I think that the needle should at least jump when you turn the key On or crank the engine if not show a few RPM.

If you can get on the forum while you're there somebody can probably walk you through some steps once you get a few results. Take a lap top, maybe there's free wi-fi nearby.

[Virto]

As I recall from all my fuel delivery issues, the tach will bounce when the engine is cranking. Should be fairly obvious if it's not connected, at that point.

He stated that he verified 12V on the injectors, but I'll pull all 6 and test both leads. Checking that coil wire physically will probably be the first thing I do, as well as the ground wire on the battery negative terminal.

I'll take my phone with me, just in case - not ideal for typing, but it can do the job.

I just need to get her going so I can get it back home into the garage, where I can cut off the rust before winter comes. After that, I'm going to teach (hopefully) myself to weld. Seems like a vital skill with these cars unless you have countless thousands to pay body shops.

[FastWoman]

Welding... I tried that once! Well, at least I tried. I'm sure it's a learnable skill, just like any other skill.

I have nothing to add about the ECU. If it has power, ground, and ignition pulse to #1, then it should be grounding your injectors. If not, then you might have a bad ECU.

I'll mention one thing, though: You should be able to fire your ignition manually by connecting a wire to the (-) side of your coil and tapping it to ground somewhere. Every three taps/sparks should get you an injector pulse. It might be easier than cranking your engine. Don't touch the bare wire, because the flyback could give you a jolt.