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No spark or injector pulse

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Old 09-11-19, 09:42 PM
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Are these red and green wires important?
Old 09-11-19, 09:47 PM
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Also do the brake and clutch pedal sensors need to be plugged in and in the correct position (aka clutch and brake pedal pressed) to get spark?
Old 09-11-19, 09:56 PM
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Would having my injectors wired backwards (primary plugs on secondary injectors) show me similar situation that I'm dealing with? im not even sure if this is possible just trying to think of everything
Old 09-12-19, 07:30 AM
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Originally Posted by Clubuser
No need for an oscilloscope. I do it w/my multimeter set to Duty Cycle. And the ECU's ground on the S4 TII is on the rear iron directly below the TB's elbow.
I guess my Fluke isnt fancy enough...

Originally Posted by Rg23
What controls the fuel pump relay? Where does it get its power from? I know the engine fuse under the dash needs to be good



Originally Posted by Rg23
Does the motor need to see fuel pressure in order to send spark?
No.

Originally Posted by Rg23
Does the key/ignition cylinder need to be grounded?
Should be grounded through the steering column.

Originally Posted by Rg23
Are these red and green wires important?
I think those are just for the illumination ring.

Originally Posted by Rg23
Also do the brake and clutch pedal sensors need to be plugged in and in the correct position (aka clutch and brake pedal pressed) to get spark?
If the clutch switch wasn't working the engine wouldnt turn over. I believe the brake switch is only used for cruise control and ABS (and the stop lights).

Originally Posted by Rg23
Would having my injectors wired backwards (primary plugs on secondary injectors) show me similar situation that I'm dealing with? im not even sure if this is possible just trying to think of everything
Yes. The secondary injectors dont even start to fire until around 3500rpm. If theyre wired wrong that could very well be your issues.

If you want to dig into the wiring diagrams... http://foxed.ca/index.php?page=rx7manual#secondgen

Last edited by FührerTüner; 09-12-19 at 07:33 AM.
Old 09-12-19, 11:05 AM
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So with the yellow plug jumped, the fuel pump turns on with key on and the fuel pump relay clicks on. I rechecked all of my grounds again, everything is fine. I need to ground out the key cylinder, I will update after that
Old 09-13-19, 09:52 AM
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Have you tried to prop open the AFM door to bypass the relay? Also the ENGINE fuse blows easily if you work on the intake and don't disconnect the battery.
Old 09-13-19, 09:54 AM
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I have tried messing with the afm door, still no luck. And the engine fuse is fine, I check it often and have swapped it twice just to be sure
Old 09-13-19, 10:17 AM
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Check your fuel lines where they attach to the fuel rail inlet and exit and make sure theyre not backwards. The inlet is the nipple closest to the pulsation dampener. On a USDM S4 TII the inlet should be on the primary rail.

Last edited by FührerTüner; 09-13-19 at 10:35 AM.
Old 09-13-19, 10:21 AM
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Would having the fuel lines swapped have any affect on spark? Or injector pulse
Old 09-13-19, 10:27 AM
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Originally Posted by Rg23
Would having the fuel lines swapped have any affect on spark? Or injector pulse
I was assuming you had spark and injector pulse. I hadn't read anything that suggested otherwise.

What it will affect is fuel getting to your injectors.
Old 09-14-19, 11:43 AM
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Does anyone have a picture or location for every plug on the harness, I thing I am just missing a plug or module somewhere
Old 09-14-19, 02:06 PM
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Some of the things you say and do make me question your ability to diagnose this issue.

You don't have to open the circuit opening relay to test it. That is actually a great way to destroy it.

I don't think the injectors wires could reach anywhere other than where they should be. Don't quote me on that though.

You know that the fuel pump isn't working properly with the stock wiring setup and you choose to ignore it.

You didn't test for codes which is a good way to know if your ECU is even powering up. Hell you might even get a code.

You say the wiring is the EXACT same. You didn't confirm that you are using a FRONT HARNESS that has been tested and working properly.

Things to do:

*Test and repair fuel pump circuit.
*Test grounds at the ECU
*Check for Codes
*Test continuity of CAS wiring.
*Test for 12V at the injectors.

If you don't do these things you will be running in circles man. Stop guessing and start testing.

Last edited by Rotary Alkymist; 09-14-19 at 02:11 PM.
Old 09-14-19, 02:42 PM
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Fortunately I have two opening relays. One does have the cover off and I can see it energizing with the yellow plug jumpered. One thing I did not know until now is that it grounds out through the afm once it opens during cranking. Will test the opening relay further with no jumper wire.

The Injector wires was a dumb thought, when I pulled the UIM I realized that there is only one way the wires can be hooked up.

I am using the same front harness from before as well. I have all of the relays grounded and all of the little ground wires at good ground points.

I will test continuity for the CAS wires and see about pulling codes

​​​​​
Old 09-14-19, 03:22 PM
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I wouldn't say dumb, just a bit inexperienced. I'm just trying to help you look in the right places without tearing your car apart. In many cases unplugging stuff leads to more issues and electrical gremlins that, if left in the hands of the inexperienced, will be impossible to pinpoint.

I know you don't wanna hear it but take the UIM off and confirm whether you have power at the injectors or not.

All fives things I listed in Post 22 have to be completed. If you do ALL OF THOSE THINGS you will actually walk away with answers, that I can promise you.

Edit: So you're UIM is off(just sunk in)? Perfect.

Last edited by Rotary Alkymist; 09-14-19 at 03:25 PM.
Old 09-14-19, 03:31 PM
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When you say the relays are grounded... are you adding ground wires? If so this is very unnecessary. Have a bit of faith in the stock wiring.

Instead you should be testing the ground wire that's associated with a particular component. If it's good then it's good. If it's not then find out why.
Old 09-14-19, 03:35 PM
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I should mention too that you should review how to test a relay... I feel that you might be testing them incorrectly and leading yourself down a pain stricken path.
Old 09-14-19, 03:36 PM
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I did not add ground wires, I just cleaned the chassis paint at the mounting point
Old 09-15-19, 06:02 AM
  #43  
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Remember that the gournd point is through the threads on the bolt, not the area where the ground touches the body on a ground point. Ensure the threads are clean and free of corrosion. Run a tap through the threads on the nut to ensure the threads are clean. Also consider replacing the bolt if the threads are very rusty. The ring terminal for the ground should also be clean and free of corrosion. I'm diagnosing the same issue on my son's 88. I will keep you posted if I find anything different than you find.
Old 10-17-19, 10:14 AM
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Any progress on your end?
Old 10-17-19, 10:16 AM
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Unfortunately not yet.
Old 12-02-19, 09:28 AM
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Had same problem intermittently. Discovered it was bad contacts at the crank angle sensor.
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