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No spark or injector pulse
Hello, I have an s4 turbo ii stock motor/ecu/harness. My current issue is I'm not getting spark or Injector pulses.
Things I have checked: CAS sending signal to tach Both ignitors getting 12v key on ECU receiving 12v at the small plug on ecu (have 2 ecus), neither make a difference Checked ECU ground on rear iron Brand New emissions wiring harness TPS and pressure sensor has 5v at brown signal wire Attempted to get spark with maf plugged in and not plugged in Tried two different ignitors Checked all fuses in engine bay and under dash Tried 4 different CAS My only question mark is the opening relay doesn't close on its own, but if I hold the contacts together in the relay it doesn't make a difference |
Check for 12 volts at the check connector on the leading coil while cranking.
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looking forward to the solution. can't think of anything else left unchecked!
best of luck.... |
Jump the yellow connector under the hood on the passenger side. Does your pump turn on?
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The fuel pump does not turn on, however I have it wired to a switch. That gives me an idea though. Maybe I need the fuel pump to be connected to the stock location in order to complete the circuit.
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And I am getting 12v to the coils and my ecu in the crank position
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Hooking up fuel pump to stock location didn't change anything
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Perhaps my ballast resistor took a shit on me. Any way to test/bypass it
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It's worth testing yeah.
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Can I just make a 5 pin jumper and jump all the pins together just like you would do to run high impedence injectors?
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After doing some more research, it has to be a grounding issue. Since the coils have 12v and the CAS is working, the ecu should be sending ground pulses to the coils and Injectors, correct? Well since everything else checks out, the only thing I'm missing is the ground signal from the ecu. If the ecu has bad grounds it won't send out a proper signal.
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You wont see the injector pulses without an oscilloscope. A volt meter wont work. FYI ECU main ground is on the top of the trans bell housing.
Accidentally scrolled to far down and found this post by HAILERS.
Originally Posted by HAILERS
(Post 9801097)
How do you know the ECU is'nt pulsing a ground to the primary injectors?
One way to almost confirm there is a pulse by the ECU, is to crank the engine over as to start the car, and watch the tach needle. It should make very small bumps up/down as the engine is rotated. That means the trail coil is being pulsed by the ECU and I"ve found in the past that it also means the primary injectors are gettng pulsed by the ECU (used LED light tapped into the primary injector wiring at the ECU's small plug). I assumed you have spark since you didn't mention the lack of spark. If you have spark, then the CAS wiring to the ECU is good and not the problem. You did not mention if you have gone to the small plug on the ECU and checked for POWER on the light green wires when the key is put to ON. Should be there. IF not, then find out why not. A reason for NOT is having the solenoid resistor disconnected on early series four cars. The ENGINE fuse and both EGI fuse have to be good to have spark/fuel on a series four car. |
My tach is moving with the CAS. I'm getting power to everything that requires 12v. I'm getting the 5v signal from the brown wire at the TPS, pressure sensor, and MAF sensor.
As far as chacking for spark and injector pulse, I have the CAS out and I can spin it my hand. The tach jumps with the spins. I have an in line spark light, also the Injectors are pretty loud and I would be able to hear them clicking away. I've used this method in the past and it's very obvious when everything is working correctly based on sound. |
Originally Posted by FührerTüner
(Post 12370148)
You wont see the injector pulses without an oscilloscope. A volt meter wont work. FYI ECU main ground is on the top of the trans bell housing....……....
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Originally Posted by Rg23
(Post 12370155)
My tach is moving with the CAS. I'm getting power to everything that requires 12v. I'm getting the 5v signal from the brown wire at the TPS, pressure sensor, and MAF sensor.
As far as chacking for spark and injector pulse, I have the CAS out and I can spin it my hand. The tach jumps with the spins. I have an in line spark light, also the Injectors are pretty loud and I would be able to hear them clicking away. I've used this method in the past and it's very obvious when everything is working correctly based on sound. If all is ok to the eye under the hood, have good compression, fuel pressure and timing is correct, engine should simply fire right up. Was the IC removed and put on correctly? Is the AFM correctly on. No major leaks. is it working? Is the engine flooding? Is the CAS installed correctly? |
So to recap because apparently I wasn't clear. This exact sep up, down to the body harness, engine harness, ecu, motor, trans, everything! Was in another chassis set up and runing about 3 months ago. That chassis didn't have a title so I decided to swap chassis.
Currently the car is set up exactly the same. I have the CAS out and am testing everything by spinning the CAS by hand with key on. No spark, no fuel. I think I probably am missing one thing in the harness that isn't plugged in, or I missed a ground |
Ok. How exactly is your pump set up? If you need a relay buy it and fix it properly and with the stock set up.
By body harness do you mean front harness? In any case I would also focus on checking for continuity on all four CAS wires. It does sound like your CAS isn't working properly. The chances of four CASs not working is basically impossible. Those things last forever. |
Have you tried fetching codes?
Have you actually taken a spark plug out to check for spark? I mean if your tach is jumping...something isn't adding up. |
The circuit opening relay is important. It powers your fuel pump and your AFM.
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I have pulled the plugs and checked for spark by grounding them to the chassis. The fuel pump relay might be the issue. I'll pull the case on off it and verify it is working.
I have my fuel pump wired off a separate relay with a switch to turn the relay off and on. And then I have ground and power going to the stock 4 prong plug, with the other two prongs not being used |
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
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Coming off the same wiring bundle as the fuel pump opening relay there is a 4 prong plug with only two wires going to it. Black/white and yellow. Does anyone know what this connects to?
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Does the motor need to see fuel pressure in order to send spark?
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Does the key/ignition cylinder need to be grounded?
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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?
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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
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Originally Posted by Clubuser
(Post 12370168)
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.
Originally Posted by Rg23
(Post 12370432)
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
(Post 12370452)
Does the motor need to see fuel pressure in order to send spark?
Originally Posted by Rg23
(Post 12370453)
Does the key/ignition cylinder need to be grounded?
Originally Posted by Rg23
(Post 12370454)
Are these red and green wires important?
Originally Posted by Rg23
(Post 12370456)
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?
Originally Posted by Rg23
(Post 12370457)
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
If you want to dig into the wiring diagrams... http://foxed.ca/index.php?page=rx7manual#secondgen |
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
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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.
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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
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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.
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Would having the fuel lines swapped have any affect on spark? Or injector pulse
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Originally Posted by Rg23
(Post 12370738)
Would having the fuel lines swapped have any affect on spark? Or injector pulse
What it will affect is fuel getting to your injectors. |
Does anyone have a picture or location for every plug on the harness, I thing I am just missing a plug or module somewhere
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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. |
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 |
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. |
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. |
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.
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I did not add ground wires, I just cleaned the chassis paint at the mounting point
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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.
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Any progress on your end?
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Unfortunately not yet.
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Had same problem intermittently. Discovered it was bad contacts at the crank angle sensor.
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