280zx turbo ECU with side mounted potentiometer

[Dave WM]

PN A18-000 203

23710 F5910

works fine on my test stand, but has a hole next to the side mounted LED opening with what looks like a slotted round shaft. Its a pot, have not messed with it.

I tried searching on the PN the 203 does not match with any thing. Talked to Jim Wolf tech support, they thought it could be a JDM thing, had not seen this either.

since its a pot I don't think its for reading out data anymore. Its actually hooked up like a variable resistor (only two wires to the pot). 

The engine starts and runs fine, goes into closed loop (blinking of led after warm up an over 2k rpm).

Below I started the video where I noticed the extra hole with the slotted shaft inside. I will be adding a video later with the ecu opened up to show the PCB's 

 

 

Edited November 8, 2023 by Dave WM

[Dave WM]

inside the ecu

 

[Dave WM]

I think this maybe a L20et ecu, and that it may require dropping resistors to work properly. I have contacted the seller to clarify why it was listed as a L28et ECU 1982/83 unit.

[dutchzcarguy]

Hi Dave, Nice to see these ECU's opened up.. I did last year a Non turbo.. they are completely different..

I would mot worry to much about the capacitors.. yes maybe the electrolite ones there are a few but the parts nissan used in these ecu's are high standard.

I understand that the problem you have is that it will not rev above 2000 rpm's ??

Maybe the ecu get's foulty signals and want's to protect the engine..  As an electrical engineer i think it's not your ecu that's the problem.

You should check the signals it's getting from the engine..

 

If the other "new"ecu is from another 20e (turbo?) then it could work also it's just that there may be some differences in rpm points were the 2,8 ltr go's not or even further with injecting etc etc..  

Btw, nice test stand!

Mart.

[Dave WM]

It all seems to work at least on the stand, it just I am concerned about the need for resistors in the injector + lead. A part diagram showed them. I contacted the seller, he is sending me a different part that should be an exact ecu for a turbo L28et, will give that a try when it gets here and do an update. 

No issue with RPM's etc that is fin on the test stand. 

[dutchzcarguy]

I think all the injectors have a resistor inline. They are normally in the corner of the engineroom on a aluminum cooling block/frame.

I wondered always why there are 6 transistors to open the 6 injectors.. they all open together at ones.. at least the non turbo's do.. They all inject at the same time independant of when theire cylinder needs the gas..

Also.. normally you can NOT put 12 volt on a injector, it will get damaged direct on a car battery.  You CAN test them with a little 9 volt battery you find in those firedetectors and remotes or so.  They don't have the current to hurt the injector, just give the injector a pulse with the 9v battery, if you ever need to test one. (Put also some carbcleaner in the injector when you do!)

Btw.. did you test in the video without injector-resistors ??  I would think that's lethal to the injectors!

[Dave WM]

The test stand uses a turbo wire harness, it does not have a provision for the resistor pack like those on the  early 280z fuel injectors. 

I dont know enough about the ecu used on the L20et (which seems to be this one) to know for sure what it was using in the way of injectors/resistors/impedance. Been hard to find data on it. IF i had a L20et setup car then I could tell for sure by just looking at the wire harness for a plug to use a resistor pack. The 280zx turbo ECCS wire diagram does not show resistors. From what I can tell the injectors specified are low impedance so it would follow that the ECU deals with the issue with out the need for outside current limiting.

 

When I do testing on injectors I generally use a variable voltage source. I often will use a transformer coupled to variac and a single diode for a 1/2 wave 30 hz pulse This isolates line current and lets me adjust the current with the variac to just enough to trigger the injectors. I have found they need around 200ma IIRC to operate. Granted the pulse is sine not square, but I assume for testing that is ok. I just want them to open and close while I pump cleaning solution thru them. 

[Zed Head]

On the 280Z EFI engines Nissan stopped using the dropping resistors in 1982, for both EFI and ECCS engines, according to the FSM's.  

The FSM mentions current and voltage protection, but the injector solenoid coil is essentially the same as any relay coil.  Seems like protection would be more for the ECU.  Of course, current and voltage are related.  A resistor won't lower voltage unless there is current.  So, in terms of "breakdown" voltage, it seems to be a wash.  Must be a current issue.  But the injectors are cooled by gasoline.  Just some random ramblings...

1981 Turbo Supplement

1978 EFI.  Current and ECU -

 

[Dave WM]

The problem I have is lack of documentation on the ECCS ecu's I have. Not sure about the manufacturing date based on the numbers. When I had them apart they all seemed to have the same driver type transistors (total of 6) and seemed to have high wattage power resistors on the boards. I did not try to trace them to see if the collectors were connected to the resistors, or if the resistors were going to the grounding pins on the injector plug of the ECU. 

the odd ball ones I got off ebay are:

A18-000 203 23710 F5910, which seems to be a L20et, not sure how to tell the years.

A18-602-045K the last 280zx turbo ecu A18-602  listed on Jim Wolf site was a A18-602-044. so is a 045k ok in lieu of a 044?

The one I got with the engine was 

A18-605-047 which is listed on the JW site as a 83 turbo ecu. it uses the same type of output transistors and I see the same power resistors on the PCB.

Based on a cursory examination of the PCB's the layout and parts look similar to the unlisted ECU's. That being said they all work and seem to throttle well, but i have not tested them with the engine under load, just blipping the throttle. I have no idea what mapping is used or if it would be ok.

Regardless the seller was ok with just sending me another unit which should have a PN that crossed directly to the 280zx L28et later model, so will just stand by for that.

Will update when it gets here.