Adaptronic modular
ID1050 injectors with adapter pigtails
IGN1a ignition in direct fire

I'm back with another good one boys....I'm currently running on only the front rotor. If I swap the primary injector connectors around, then the car will run on only the rear rotor. So there seems to be a problem with my rear primary injector wiring, but I can't figure it out.
factors to consider:
1. Engine harness is in good shape, not a brittle wire on it. Was working fine recently. The rear primary wiring passes visual inspection (w/out opening up the harness) and is getting power to the connector.
2. I was troubleshooting some fuel pump problems a couple weeks ago and grounded fuel pump related pins on the ecu connector with key on and the other 3 ecu connectors still connected to the ecu (heard this is a nono)
3. When I was troubleshooting the injector problem, I unplugged one of the primary injectors while the car was idling on one rotor, and my rear trailing coil exploded almost instantly after (not sure if related). Put a new one on and have been screwing with the car idling and what not for a while and there is no sign of coils getting hot or any ignition problems at all since then

So far we have it narrowed down to possible shorting inside the injector connector (swapped around the adapter pigtails with same results, so those check out) OR the injector driver melted down in the adaptronic. Took apart the ecu and everything looks good and doesn't smell burnt. Just seeing if you guys had any ideas or can think of anything else to check. Thanks.

 

check continuity on the rear injector wires.

 

I am really an electrical noob. I need a little more hand holding. Would the best way to do this be to: figure out which pins on the ecu connector correspond to the two wires on the rear primary injector connector, set my multimeter to 200 ohm, then stick one probe to the ecu connector pin and the other probe to the corresponding wire in the injector connector? Key off I assume since we're just testing if the wire is broken or not? What kind of numbers should I be looking for?

 

all right, as long as I did that right, I got .01 from the end of the injector connector to the ecu pinout on the green/black thin wire and .09 from the end of the injector connector to ground on the the thick black wire. I measured the front primary connector for fun and got the same results.

 

The black wire isn't ground, it's 12v always on. The ecu grounds the injector pin(green/black wire) to complete the circuit. The result for the green/black is right.
Injector driver won't always show any physical damage/smoke if it failed

 

All you did was check continuity of the wires using ohms. Since you have a value at all it means there's no break in the wire. The tricky thing here is that the injector wiring is kind of all shared amongst itself. Having an ecu issue would be possible but unlikely since when you switch the plug you can shift the issue from one injector to the other. So that rules out the injector itself.

These are my suggestions based on what you've already done:
Unplug the ecu and check for continuity for each injector wire. There's an ecu pin out on Google. Go one at a time. Set your multimeter to the symbol with the arrow pointed to a line. Stick one probe in the ecu plug end and the other at the injector plug end. It doesn't matter which probe goes on which end. Doing them all will verify the integrity of the crimps within the harness so you don't have to open it.

Ohm out the primary injectors anyway. Even though you can get them to work indepent you should check them anyway. Set your multimeter to 200ohms and stick the probes on the pins on the injector.

Verify that you have the correct plugs on the correct injectors.

Try a different ecu



Do those things and report back. Based on what you said, this should be pretty simple to solve. There's not much that it could be

 

With the multimeter set to the arrow pointing at the line I'm getting 020 to 035 reading on all injector wires. And 10.5 ohm on all injectors. Since all of these are pretty consistent I assume I'm looking at an ecu issue then? I haven't tried a different ecu yet, I'll have to track one down to try out.

 

That does sound like a possible ECU issue. Another thing you can do to double-check is measure voltage for each pin on the injector connector. For instance, multimeter in Volts DC mode (20V max, if it forces you to select a voltage range)… red multimeter probe goes to the pin on the injector connector (black wire) and black multimeter probe goes to engine ground or chassis ground. With the injectors unplugged and the ignition key on, one of the pins should show about 12.x Volts (battery voltage) and the other pin should show 0V.

If the injector was plugged into the connector and you back-probe those same pins, both pins will show 12V. Don't try to back-probe if that's something you're unfamiliar with, doing it wrong can damage the harness and/or connector.

Be careful about testing with a spare ECU... it's pretty uncommon for ECUs to just stop working. Don't run the car on a borrowed ECU for long, in case something in your car's harness hurt your original ECU.

 

Exact same thing happened to me last week. One wire worked it way theough the heat shrinking and touched the other wire. Ended up shorting out the rear primary injector control on the ECU. No evidence of a short on the circuit board though. Got another PFC and everything worked like a charm.

 

Yeh, it's usually not visible, i've actually replaced a couple drivers on PFC as long as part is still available (NEC upa1556ah). Might even have one left, had to order a few from china a couple years ago.
https://www.rx7club.com/power-fc-for...driver-999502/

 

Thanks for the link. I do a lot of micro soldering so switching that should be a breeze. I didn't have my tools with me when this happened so I couldn't pursue the short any further than a visual inspection.

 

I've had the best luck getting the part on ebay of all places,probably fakes but still work fine, should have no problem soldering it it's all massive components lol.

 

Put a noid light in the injector plug and see if the ECU fires it. You don't need to swap ECUs yet.

 

I finally had time to get into the garae for more testing. I did what you suggested and got 11.6v on the thick black wire and 1.1v on the thin green wire (not sure if this may be part of the issue, or my shitty harbor freight multimeter). I plugged the connector in to the injector and saw 11.6v on both wires with the back probe.

I don't have a noid light so I used an LED I had sitting around. I wired in a resistor from an old amplifier, I'm not sure what ohm it is but I saw 110 ohm on this set up with the multimeter. I tested the "noid light" set up on a spare battery and the light lit up.
I connected the "noid light" set up to the injector plug and started the car. No light. I even tried it w/out the resistor and still no light.

I think this seals the deal right?

 

It looks that way.
My criteria would be this.

1.Continuity between the wiring at the ECU and the injector plug.

2. 12v at the injector plug on the hot side

3. Proof the injector works (you did that)

4. No broken, loose or misaligned pins at either side

If all of those things check out, you have a bad ECU imo.

 

Problem solved. New ecu fixed it.

 

I replaced the injector driver on my Power FC. I used a Yihua 862D+, a heat gun, a solder sucker, and flux to do the job. The whole job took approximately 30 minutes from opening the ECU to closing the ECU.

The bad component:


Removed. I used a heat gun to warm up the board and then the hot air gun from the soldering station to melt the solder. The lifted the chip out using a set of tweezers.


No signs of damage.


Old one on the left. New one on the right (I ordered two new ones just in case)


Holes cleaned using a soldering iron and a solder sucker


New one soldered in. The leads are too long so I clipped them after


All done. As good as new.

 

Is there any way to test the injector driver with a meter or some other test to know 100% if it's bad?

Nice writeup, H_M!

Dale

 

I second this. That's the whole reason I bought a new ecu instead of just the driver. I still wasn't 100% certain it was the driver so I figured it was better to spend 1400 on a new ecu that I could return or resell, rather than 600 on a new driver that I would be stuck with if it wasn't the real problem. Awesome write-up, I may still get a driver and repair the old ecu to sell now that I see it's not too difficult. Thank you

 

The part was about $13Cad for two. You can do the repair with just a Radioshack soldering iron, some solder, and some soldering wick but it's more tedious.

You should be able to check the driver for a short. Put your multimeter in to continuity mode and poke around.