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Discussion Starter #1
1984 Turbo 5-Speed Coupe, non-AE50th.

OK, this is the background:

1.car not starting, not battery-related.

2.car turns over but seems to get no fuel. added gas to tank. same result.

3.tested distributor, spark plug wires, getting spark to plugs okay

4.replaced spark plugs with new NGK's

5.pulled fuel line from top of filter, got fuel pressure (soaked me with gas)

6.disconnected air filter at resonator, sprayed carb & choke cleaner while cranking. result : car starts and runs on cleaner while spraying.

determination by experienced mechanic : ecu is fried and not firing injectors.

i would agree with him without question, but we ran the ECU codes and got these:

23 - Idle Switch
24 - Neutral Switch
31 - Air Conditioner (no surprise, my A.C. compressor isn't belted)

Would these two codes (23,24) cause my ECU to not fire the injectors intentionally so I can't run with these error codes? I know nothing about the electronics of a Z31, so I'm looking for some sage advice. I just don't want to dump money into a new ECU if theres something else causing the problem. I just dropped the transmission to replace the clutch, and I may have upset something in the process. Anyone have any information on the Idle and/or Neutral switches? I basically just want to know that replacing my ECU should be my frist course of action for sure or not.

Thanks guys,
 

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Discussion Starter #3
do you mean i should hear them click if they're firing properly? and take the cap off or the whole distributor?

i already checked all the injector connectors and they look ok.
 

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Just being able to get codes out of the ECU is one indication that the ECU isn't "fried". Being able to get a spark is also a good thing.

What procedure was performed to get the codes? Getting 23, 24 and 31 suggests to me that it was not done to FSM spec. During the diags was the throttle pushed, gears shifted and aircon turned on and off?
However, none of those codes should prevent startup.

Red october's test is a good one. I'll add that since you have already established that you have spark, while performing this test you should ground the coil HT lead, just to reduce the risk of igniting whatever fuel might get injected with the engine stationary.

BTW, an "experienced mechanic" should possess a cheap "noid light" which plugs into the injector connector (on the harness side) and verifies the injector electrical supply. Just a small light globe can be wired up to do a similar thing. Noid lights should be able to be bought at any decent auto parts store.
 

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Yes, you should hear the injectors click.
On a really sweet condition motor, you should hear them clicking while it is idling.
 

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Discussion Starter #6
Mister_T : yeah, he has an electrical test probe with light, and we used this to check all the fuses. i don't recall seeing him probe the injector connectors themselves, but i will make sure and do that myself when i go in to troubleshoot. I would have done the ECU check to manual specs, but I couldn't seem to find my Haynes, so all we did was turn the key to "ON" after turning the diagnostic screw. That's how those codes came up.

I think i understand red's test now...since the ignition is set to "ON", when I manually turn the distributor rotor it *should* click each injector open just before each spark, right? so if i hear no click, the injectors aren't opening with the distributor, and the ECU is quite possibly my suspect?

Sorry if i'm slow at getting this, but i'm not much of a mechanic yet, and learning as i go.

My only other thought is that the wiring is all messed up from whoever worked on the electronics before me. There's electrical tape everywhere and frankly, it's quite messy. I'll try to trace my injector wires and see what shape they are in.

Thanks again,
 

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Discussion Starter #8
1sikZ-

I had considered that. This is assumption on my part, but isn't it likely that only one injector would die out completely at a time? If so, I would expect to have a car that will start but only combust on 5 cylinders. Also, it ran just fine a couple of months ago before I left it sitting. I don't think the injectors would all go bad in that time period.
 

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Discussion Starter #10
It was first parked in my driveway in April, and started it every couple days until about June, but didn't drive it as the clutch was out. Then it sat from June until mid-August. So 2 1/2 months total time without starting.
 

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Discussion Starter #11
I'm going away this weekend, but I'll be finishing the work up early next week. I'll give you guys a highway video when I get this pavement-pounder rolling.
 

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Six injectors don't die at the same time unless something pretty drastic has happened.
The injectors are fed power via the EFI relay and a fusible link to each red injector wire. The ECU fires the injectors by controlling their ground.
 
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