L28 exhaust manifold source

[Virto]

I had a feeling we'd break some, so I ordered a full set of studs from MSA when I got the exhaust. I was hopeful that none would break off so far in that they couldn't just have a bolt head welded on and then pulled out. Not so much my luck, apparently.

We shall see how things look once the head is off and we can get a better picture.

[Virto]

I'm baaaaaaaaaaaaaaaaack...

Holy hell, things have been a mess. Let's see if we can catch up on where we stand.

The car has been at the same garage for over a year at this point. Once winter set in (and boy, was it a LONG winter in Chicagoland) I made the call to just leave the car there rather than pull it outside and risk salt exposure - it's rusty enough, as it is.

The head came off and got sent out, came back beautiful and clean - replaced the valve stem seals and removed the nasty old stud. It's back on the car, timing cover is back on, headers are on, all good, right? Of course not.

The TB to intake manifold boot disintegrated, as they're prone to doing. I ordered one from MSA, but they were backordered. Somehow, they still managed to get it to me within 2 weeks. I could have rigged something, but the late 77 and 78 boot has the side spout that connects back to the manifold.

So, awesome. Back in business! Ha, you should all know better than that, by now.

It won't start. Fuel pump runs, car cranks no problem. Injectors have 12v with key on, but no pulse. NOID light never so much as flickers. Now is where I get to beg for help again. I'm desperate to get this thing back home and in my own garage again, where I can cut out more of the rear wheel well than I had originally planned (yay for an extra year of rust).

I know the mechanic at the garage will eventually figure it out, but he's the stereotypical old man mechanic with a heart of gold that spends 10 hours a day fixing bad brakes and old clunkers asap for people that don't have a lot of money. He just doesn't have the time to commit to diagnosing this thing for a full day. I can get to the car once a week or so (my work schedule sucks) during times that don't make it look like I'm robbing the shop when nobody is there. I'll probably get over there this weekend and try my best to make it go.

Any ideas where I should start? I'll wiggle a ton of wiring around and look for loose connections. I THINK I'm right in saying that, with 12v at the injectors, that the ECU isn't toast, but I don't know about the relay for the FI. Of course, 78 has a different relay that nobody has aside from Z Car Source and it's over 200 bucks used before a core refund. Hoping that's not my issue...

[Zed Head]

The injectors are opened by the ECU when the ECU gets a signal from Pin #1, which is connected to the negative side of the coil. So you need spark, and you need the Pin 1 connection.

[Virto]

OK. There was spark when checking by pulling the boot away from the plug, but I'll check it again to be sure. I'll take a look at any connections running from the coil. I assume that's standard across all 280Z years - the FI bible was last revised in '75, so I'm not entirely sure what differences I'll run across.

Edit: Could testing PIN1 for battery voltage diagnose an issue with wiring between the coil and ECU, rather than tracing back all the wiring?

Edited August 26, 2014 by Virto

[Zed Head]

Your 78 won't have the ballast resistor. So the Pin 1 wire will come directly from the coil, it's a blue wire. But if you have spark then the connection at the coil is okay.

But here's another thing I remember - the blue wire from the coil also runs to the tachometer, as well as the ignition module. If the tachometer is disconnected, it screws up the signal to the ECU and the ECU won't do its job. So your best path is to check continuity at Pin 1 at the ECU connector and to confirm that the tachometer is connected. There's a resistor in line with the tachometer that needs to be in place. It's bundled in to the wiring so won't come loose unless someone messes around with the wiring by the fuse box.

[Virto]

Seems unlikely unless some mice got into it while it was sitting. Haven't seen any evidence of that, but I'll go over it to be sure. I'll check pin1 and see what kind of reading I get.

I'm not entirely clear on the purpose of the relay in the injector cycle - I have to do some searching and reading.

The wiring in this car is a bit of a hodgepodge. I'll see if anything the PO did (or un-did) might have come loose.