No spark or injector pulse
09-08-19, 09:07 PM
#1
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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
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
09-09-19, 08:02 PM
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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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09-10-19, 12:27 AM
#11
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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.
09-10-19, 09:37 AM
#12
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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.
Accidentally scrolled to far down and found this post by HAILERS.
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.
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.
Last edited by FührerTüner; 09-10-19 at 09:44 AM.
09-10-19, 10:49 AM
#13
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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.
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.
09-10-19, 11:43 AM
#14
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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.
Last edited by Clubuser; 09-10-19 at 01:00 PM.
09-10-19, 12:49 PM
#15
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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.
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?
Last edited by Clubuser; 09-10-19 at 02:11 PM.
09-10-19, 08:07 PM
#16
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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
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
09-11-19, 05:24 PM
#17
Sucker for Punishment
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.
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.
Last edited by Rotary Alkymist; 09-11-19 at 06:37 PM.
09-11-19, 05:32 PM
#18
Sucker for Punishment
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.
Have you actually taken a spark plug out to check for spark? I mean if your tach is jumping...something isn't adding up.
Last edited by Rotary Alkymist; 09-11-19 at 05:44 PM.
09-11-19, 06:39 PM
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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
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
09-11-19, 09:01 PM
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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?
