L28 Injector firing order- unlabeled harness.

[Ben280]

Hello! So my newly acquired Z came to me in reasonable shape, apart from the engine bay, where everything was unlabeled and unplugged to boot!

 

I did some work on it and got the engine to fire up and was able to drive it around, but after some use, it looks like cylinders 1 and 5 are not getting. I blamed it on clogged injectors and 900 year old fuel lines and rails, but I am also wondering if I hooked up the harness incorrectly. I assumed the engine wouldn't run if the wires were hooked up backwards but I've been wrong before.

 

All my injector plugs are VW/Audi type ones that have been spliced into the original harness. Is there a way to easily determine proper order on the injectors without tracing the harness back to the ECU? And is there a way to check polarity (if it could be an issue) or pulse to the injector?

 

I'm new to electrical trouble shooting but all help is very much appreciated! Thanks!!

[I'm BLUE]

Well... understandably ,,, this is why labeling is important ( bad previous owner ! )

 

I imagine because of the length/layout of the harness ,,, and position of those cylinders ,,, that it would be very hard to mix up both of those injector connection's with the exception of wiring in new style connectors.

 

I will see if I can get a better up close pic of my ZX injector harness layout posted tomorrow ,,, or you may be look at a picture of a 280z injector/fuel rail area online and attempt to deciper order if need be ? ( I am tired )

 

 

use a "noid light" to check for power/pulse to injector connectors.

 

 

Perform a compression test ( wet and dry ) ,,, and have fuel injectors cleaned/checked for flow. Or install re-manned injectors. I simply put 1 bottle of SeaFoam through the gas-tank and 1 bottle through the intake ( brake booster hose on intake mani side ), It probably will not cure REALLY clogged injectors , but def helps get the process started !

[Ben280]

Thanks for the tips! I'll definitally do SeaFoam through the gas tank. I got frustrated with the issue (its a few weeks old) and decided it would be a good time to add a Pallnet fuel rail and get some new injectors.

 

Being an electrical noob, what is the proper procedure for hooking up the "noid light"?

 

Thanks again!

[ggzilla]

I believe there is no "firing order" on 280Z fuel injection. It is batch-fire, all injectors work at the same time. Only SEFI (sequential EFI) has an order to it.

 

Most new cars still use batch fire. SEFI is better for emissions, but only minorly better.

[ArchetypeDatsun]

+1 ^ ^ ^

[Willdatsun]

try swapping the plugs around from neighboring injectors to see if fault moves over.

 

Common fault is the resistor pack on the inner fender getting corroded joints where they are joined inside the pack.

[Ben280]

Good tips all round here, thanks! I'll give em a shot this weekend and see what I can come up with!

[Skib]

I believe there is no "firing order" on 280Z fuel injection. It is batch-fire

 

 

they are

[Ben280]

So with the batch system, is it making all 6 fire at the same time? or is it grouped, like 123, 456?

[ggzilla]

I think only the V6 ran group-batched. The Nissan VQ 300ZX ran sequential.