1977 280z EFI Nightmare

[Reptoid Overlords]

6 hours ago, ckurtz2 said:

Are you positive that fuel injectors can be wired backwards with no ill effects?

 

Yes..for what it's worth, I've connected my old original injectors both ways out of the car and they squirt fuel. On a side note, I think I have the same header, the MSA unpainted header?  Anyway with a good gasket and proper torque it allows a bit more valve noise to get through than the original stock manifold.   Lash is spot on in spec(feels like puling the first stick of gum out of a newly opened pack of gum). Also my exhaust isn't welded yet from the downpipe back.  So maybe your ticking is a result of something similar.

There is an ignition control module bolted on to the distributor of the ZX.  I am unsure of it's location for your year S30. 

[Driver_X]

100% in the injectors.

 

I rewired mine 10 years ago and asked an expert the same question. I have no idea if I swapped sides when I re-did the harness (new pins & connectors and put em together) but she's been running perfectly for a decade. 

And also 100% on keeping a stock cam. This FI is "dumb" in that it's not adjustable and built and designed to work within a small set of parameters. If you want to swap in a hotter can, you need to switch to a modern FI, which can self adjust on the fly, or Carbs. 

Edited May 23, 2021 by Driver_X

[ckurtz2]

1 hour ago, Driver_X said:

100% in the injectors.

 

I rewired mine 10 years ago and asked an expert the same question. I have no idea if I swapped sides when I re-did the harness (new pins & connectors and put em together) but she's been running perfectly for a decade. 

And also 100% on keeping a stock cam. This FI is "dumb" in that it's not adjustable and built and designed to work within a small set of parameters. If you want to swap in a hotter can, you need to switch to a modern FI, which can self adjust on the fly, or Carbs. 

So you think that it is possible if the wires are connected backwards it can lead to issues?

All six of mine are wired the exact reverse of this by accident. I tested by seeing which side of the connector was getting voltage when on the car, and the opposite side had voltage as apposed to this thread. No idea how I messed this up, as I thought I was careful.

https://www.atlanticz.ca/zclub/techtips/injectors/connectors/index.html

Regarding the cam, I will stick to stock, but I think I am going to use the internally oiled one. @Reptoid Overlords, ok interesting. maybe the header is just causing more noise to pass through. I might try one of those special tools to see exactly where the sound is coming from.

[Zed Head]

2 hours ago, Driver_X said:

100% in the injectors.

 

I rewired mine 10 years ago and asked an expert the same question

Not really clear what you're saying here.  No offense.

[Zed Head]

https://tameson.com/about-us.html

https://tameson.com/choosing-an-ac-or-dc-coil-for-a-solenoid-valve.html#:~:text=Solenoid working principles&text=Solenoids are electromechanical devices that,such as iron or steel.

The polarity of the electrical contacts is not important with AC and DC solenoid valves. With AC solenoid valves, this might be obvious because the current switches polarity twice per period anyway. With DC solenoid valves the reasoning is that current passing through the coil creates an electromagnet which produces an attractive force on the armature. When current is applied through the coil, the armature will always be pulled towards the coil, regardless of the contact and current polarity.

[ckurtz2]

10 hours ago, Zed Head said:

https://tameson.com/about-us.html

https://tameson.com/choosing-an-ac-or-dc-coil-for-a-solenoid-valve.html#:~:text=Solenoid working principles&text=Solenoids are electromechanical devices that,such as iron or steel.

The polarity of the electrical contacts is not important with AC and DC solenoid valves. With AC solenoid valves, this might be obvious because the current switches polarity twice per period anyway. With DC solenoid valves the reasoning is that current passing through the coil creates an electromagnet which produces an attractive force on the armature. When current is applied through the coil, the armature will always be pulled towards the coil, regardless of the contact and current polarity.

I think I am with you on this one. In the name of science though, my friend and I are going to rewire the injectors anyways tommorow morning. If something changes then miracles are possible. If not, then you can use my forum post as proof to debunk anyone in the future who thinks that their injector wiring is wrong. 

[Driver_X]

18 hours ago, Zed Head said:

Not really clear what you're saying here.  No offense.

100% polarity doesn't matter for injector connections. Based on my experience and confirmed by the Datsun mechanic who sold me the pins & connectors to repair the corroded connections I had on my car when I did this work 10 years ago. I asked if I needed to mark the wires when I did the work & was told no need. Confirming what others have posted previously. 

100% use stock cam with stock FI. 

[ckurtz2]

Ok I am going to keep stock cam. Didn't do injectors after all, because I think I found the real problem....

So the gas was old, sitting since December, so I swapped it for new gas and also replaced the filter I had running in the back. Put about 8 gallons in. The previous filter sure did do it's job.

The first thing I ever did to the car was clean the tank with nuts, bolts, muriatic acid, and vinegar to shake all the rust out. I also cleaned out the pickup and return tubes with solvents which were clogged at the time. I then put a little filter between the fuel pump and the tank to make sure any pieces of rust or gunk I missed were caught

 Now here is where things get interesting. The car starts and idles beautifully without a miss when cold, or after sitting for about 30 minutes. Now I wondered what the hell was happening, and I knew it must be somehow fuel, even though the fuel pump bench tested wonderfully when I put it on the car. 

I went and looked at the little filter I replaced and here is what I saw.

What the hell, is what I thought. I thought that the fuel pickup must be semi clogged, but that is not the case. When the car turns off it fills up instantly. That is when I noticed this when the car is off.

This bubbles subside after about 20 to 30 minutes.

When I start the car and watch this filter the stream is consistent and powerful to the filter. Then after running for a little bit the stream starts to spurt again with less power. Like there is air getting stuck in between.

 

Have you ever seen this happen? Is somehow air leaking into the system? What is going on here, I am all eyes and ears.

I am thinking there are rust holes in the pickup causing air to surge in or something like so.

Edited May 24, 2021 by ckurtz2

[Patcon]

There have been cases of pickup tubes being bad and causing issues at less than full levels

[ckurtz2]

1 hour ago, Patcon said:

There have been cases of pickup tubes being bad and causing issues at less than full levels

I am going to agree that this is the issue because it was so hard to unclog, and I could have broken it when shoving wire and stuff through. Removing tank as we speak. I will send it off somewhere tommorow. Fingers crossed this ends the EFI nightmare for good. 

Never knew this was a problem until now, because the flow was much better before I drained the tank today, but still pulsed every once and a while. The difference is I have 8 gallons in the tank now, and I had a full tank before. Likely masked the problem until now.

[ckurtz2]

Hey guys long time no see,

      I was absorbed in a full suspension rebuild, so this thread got put on the backburner. Since I have last posted, I had zcarsource replace my pickup tube inside my gas tank. They did a great job, and it fixed the fuel flow/air bubbles problem. Now I can free rev the car easily up to 7k rpm and the car runs much better.

      However, I still have a problem with how smooth the motor runs. At idle it still bucks and jerks like it has a misfire and with the exhaust off the misfire is clearly audible. I can notice the engine bucking till about 3000 rpm, to where the motor seems to run smooth. Now as a last ditch effort to see if it was still fuel, I pinched the return line to see if it would smooth out. All that happened was the idle ran higher (with fuel leaks beginning to sprout), but still had the consistent stumble, so I doubt fuel pressure is an issue. I also want to note that I tested the fuel injection control unit, and all of the FSM tests checked out great.

       This makes me think it must be spark. However, I have a new distributor cap, spark plugs, coil, spark plug wires, and rotor. So the issue must be more complicated. I was thinking that it possibly could be the distributor? It has a small amount of side by side play, but I gap checked everything and it was almost perfect. So I am wondering if it is the transistor ignition unit on the passenger side kick panel. Does anyone know how to test this. I looked at it, and it looks pretty nasty. What are the signs of one that has gone bad? Tell me what ya'll think.

 

 

 

[ckurtz2]

Time to settle this thread Forever!

            After about a year of tinkering with a very sick motor, and doing everything per the FSM manual to no luck, I gave up and sent my Z to a doctor to be fixed. The shop I took it to was Sakura Garage in Phoenix, Arizona and I highly recommend their work, as they are some of the most knowledgeable Z car enthusiasts I have ever met. 

            Anyways, they decided something was up and hooked up the car with an AFR Gauge. With the car idling I think they said it was running somewhere along the lines of 24:1 being on the extreme lean side. So they turned my little potentiometer to control the fuel to full rich and could only bring it down to 20:1 (should be around 13-14:1 I believe). So they went through the entire EFI FSM and found absolutely nothing wrong with the car. They wondered if it was the injectors so they did full spray tests into graduated cylinders for fuel flow, consistency, and volume, and it looked totally fine. Swapped in a different ECU, still no luck! With fuel pressure solid, and literally every other option exhausted, they decided on a whim to just toss on a new set of injectors anyways and....... my motor purred like a kitten. Now they still don't know what exactly is wrong with the old injectors as they are what came with the car, OEM, and I had them rebuilt as one of the first things I did to the car when I bought the car. However, when I bought the car, (completely original) I remember the only thing disconnected were the fuel injectors. So my guess is that these injectors were the culprit to why the car was parked back in 1991. 

Anyways, glad its settled, figured I'd share this with the community in case anyone ever has a problem like I did. 

thanks @siteunseen, @Zed Head, @Captain Obvious, and anyone else for helping me a while back when I started this thread!

Edited November 11, 2021 by ckurtz2