Printable Version of Topic

Posted by: nditiz1 Mar 18 2022, 07:37 PM

As my parts come in for my L-Jet tune up, I'd like to start to plan out my test stand. Does someone have a link to a thread or just the answer of what power I need to send to the 14 pin connector to run the engine on the stand? Thanks!

Edit - See latest post on which wires were needed as a minimum.

Posted by: windforfun Mar 18 2022, 07:55 PM

12 VDC or 120 VAC if you want to cook the board & roast marshmallows. I'd shoot for a current draw of at least several amps. Happy Friday.

Posted by: nditiz1 Mar 18 2022, 08:30 PM

I see what you did there.

Which wire or wires do I need to apply 12volts or DC current to on the 14 pin connector from the cars wiring harness to run the engine?

Posted by: Van B Mar 19 2022, 09:32 AM

I don’t know how you could run the L-jet without the full electrical system. AFM, relay board, dual relay, and computer of course.

Posted by: Superhawk996 Mar 19 2022, 10:07 AM

Here's a handy diagram to the relay board. I don't know who put this together but they sure deserve a

I've been going though the schematic a lot lately trying to help Second Wind with his fuel pump & other electrical issues so had it handy. I don't know who put together this graphic but it is base off the factory manual diagram and schematics. I'm not a L-jet guy but as far as I know the relay boards didn't change between D-jet and L-jet.

Basically you need 12v power to pins 14 and 12 (14 pin connector) - these are direct feed to the relays which will in turn provide power to the ECU and fuel pump. Obviously you'll need the ECU and associated sensors injectors, L-jet wiring in place. Sensors are passive devices read by the ECU as inputs.

Pin 14 supplies 12v input to the fuel pump relay pin 30. Power from the relay leave on pin 87 and goes out to the fuel pump on pin 13

Pin 12 supplies 12v input to the power pin 30 of the power control relay. Pin 87 is the output from the relay which in turn supplies the 12v power feed to pin 85 (solenoid) of the fuel pump relay once the power control relay is energized. So the sequence is the power control relay has to be energized 1st. That provides power to the ECU. The ECU returns a ground to pin 86 of the fuel pump relay energizing the fuel pump relay solenoid.

Power (12v) to the coil comes in on pin 8 (of the 14 pin connector) and goes out on pin 7 (of the 12 pin engine harness connector).

Ground comes in on pin 10 (of the 14 pin connector)

Sorry -- lots of words. Study the diagram and it should start to make sense. Alternately maybe some body has a nice engine run stand wiring diagram for you. @http://www.914world.com/bbs2/index.php?showuser=18763

The other engine harness signals you would want like tach signal are also called out on the diagram on the 12 pin connector that goes to engine / starter / oil pressure signal, etc.

Posted by: nditiz1 Mar 19 2022, 10:34 AM

Perfect - Thanks Phil!

Posted by: wonkipop Mar 19 2022, 04:38 PM

@http://www.914world.com/bbs2/index.php?showuser=18763 and @http://www.914world.com/bbs2/index.php?showuser=22428 ,
at risk of going in over my head, cause i don't have my head around it in detail, but i don't think the L jets use much off that relay board.
compared to a D jet.

its all kind of over in the relays under that battery tray? or a lot of it.
a couple of relays there.

not sure what your are trying to do exactly nditiz, but @http://www.914world.com/bbs2/index.php?showuser=8571 B might have a point.

i haven't ever tried to run an L jet on a stand, but if i did i'd probably just try and hang all the bits of a ply board rig complete. ECU etc. and hook it up to a car battery and go.
with appropriate grounds etc.

Posted by: nditiz1 Mar 19 2022, 04:47 PM

I have everything to run it as though it were in the car and wanted to test and tune before I decide to put it in the car.

Posted by: wonkipop Mar 19 2022, 05:42 PM

no worries @nditiz

i don't know exactly, have not done much poking around on the relay board.
but a lot of it is just not used on the 1.8s on that relay board.'
there is a wiring diagram included for the 1,8 EFI in the factory manual electrical section.

Posted by: nditiz1 Apr 10 2022, 07:33 PM

Update -

I successfully ran the Ljet on the stand. As Phil said I had power run to 12 and 14 from the battery. Some other wires I used for the bare minimum were the blue wire, went to the 914 gauge pod, could have went to a bulb, but I had an extra. The black wire from #8. This was hooked to my ignition key on terminal to send power back into the relay. The black red wire went to the FP and of course the brown for ground. Yellow to ignition switch start terminal.

Shameless plug - the engine is now for sale $1300

Posted by: emerygt350 Apr 11 2022, 06:10 AM

You let all the magic smoke out didn't you?

Posted by: nditiz1 Apr 11 2022, 10:52 AM

The Dark Magic is still contained within, but now I can somewhat harness it. Although, I was skeptical at first since it has so many wires going all over the place.