No injector pulse coming from ECU S14 SR20

[carnagexxxx]

Backstory:
Car has not started since an event I did last September. The car was working very nicely until late in the afternoon where it began to act up (water temp was getting too high). I pulled it off the track and ended the weekend early out of fear of damaging anything important.

The next day I tried to start it in order to get it on the trailer but all it did was crank...no sign of ignition at all. After getting it home I eventually decided to get it back in working order for the 2013 season. Same thing...crank but no sign of an attempt at igniting fuel. (I must mention that the entire electrical system was more or less stock/factory aside from the necessary SR20 swap splices)

After trying a new igniter, new coil packs, new spark plugs and not having any luck starting it, I decided to complete a wiring project I have been wanting to do for awhile.

I am having a similar problem where my injectors are not receiving any signal for pulse. Everything else has been checked and re-checked...no fuel injector pulse. They have 12V power to each one and if I "manually" ground each one with a test lead, they click.

I have switches isolating my ecu power, fuel pump, and ignition (relays are more or less exactly like factory, just relocated). To engage the starter, I have a push-button.

I had the start signal wire from the ecu going to the side on the button that only gets 12V when the button is pressed...0V when depressed.

I have not yet ruled out a problem with the ECU drivers but I have talked to a tech at Jim Wolf Technology (I am using one of their ECUs) and he said it (although rare) is uncommon for all 4 injectors to fry at the same time.

I have checked and re-checked the following:

All grounds for the ignition and ECU
Power to injectors
Power to ECU
Continuity on all wires
Fuel delivery (fuel lines are correct)
Fuel Pump (comes on with good pressure)
Injectors (pulse when "bench" tested")

I have spark on all 4 coils and it will react to injecting carb fluid into a vacuum line but won't stay lit. I am 100% positive that the injectors are for whatever reason not getting a pulse during the ignition sequence.

My theories at this point are as follows:

1. ECU has bad injector drivers and need to be replaced
2. Some sensor/switch is not hooked up and is telling the ECU to not send any fuel.

What sensors/switches would make the ECU not send fuel?

How does the switch on the back of the clutch pedal function in relation to starting (please don't say "it completes a circuit" because that much I have gathered). What I want to know is what is the sequence of events that happens when it is engaged.

Again, before I get flamed to bloody hell, the car was doing virtually the same thing before I started working on the car's wiring and harness.

[wangan_cruiser]

i think you missed checking your cas. i had the same problem. but i found the wires from the cas were slightly pulled from the connector barely making any connections.


you could try turning the ign on then slowly turn your cas, see you can hear click everytime you turn it.

[carnagexxxx]

The CAS is something that I haven't completely ruled-out but I was under the impression that if the coils are firing, the CAS is working.

I will mention that one wire needed some attention so I de-pinned it and fixed it. There is a small chance that it's still not making a solid connection but I was pretty sure I tested for continuity.

[carnagexxxx]

Update:

After doing every diagnostic in the book including checking the CAS (swapped with a know-working CAS) and even trying some more un-orthadox tests, I ended up sending the ECU back to Jim Wolf Technologies (ECU is a JWT).

They found that the fuel pump relay driver circuit (transistor) was bad so they replaced it for $100. When this fails, it (for one reason or another) does not allow the injects drivers to proceed with their sequence, thus, no injector pulse.

Hopefully the ECU will be back in my hands on Tuesday and we'll see if there are any other gremlins hiding in my car.

[carnagexxxx]

So I got the ECU back and I'm still not getting any injector pulse. Does anyone have any ideas? I am going nuts.

[carnagexxxx]

Does anyone have any input at all?

[T0fuman]

I think we might be having the same problem.... Ive used a light tester to check for signals and when I plug it in to my injector harness I get nothing when turning the key if I gound the injector pin to the chassis I get a constant light even when the car is not on.... Constant 12v to the light with just the battery hooked up.... When I try to fire it up she sputters and trys so I figure grounding out that pin grounds out all the injectors and it tries to turn over. Im hoping swapping ECU's will fix this. Ill let ya know if I find anything. You should try grounding your pin too and turing it over. If that kinda works you know its some ground.

[g2ic02]

All the switch on the pedal does complete the circuit for the starter relay(control side), you can rule that part out. What wire do you have hooked up to your start push button. That is where I would start. I am pretty sure no ecu wires should be hooked to it. Ecu should just be hooked to key on power or in your case a main power switch.

[g2ic02]

Also when checking for injector pulse. Hook test light to positive terminal of battery and other end to the side of the injector that doesn't have 12 volts . Should flash when cranked. Next step would be to get digital scope and look at signal coming from cas.

[carnagexxxx]

All the switch on the pedal does complete the circuit for the starter relay(control side), you can rule that part out. What wire do you have hooked up to your start push button. That is where I would start. I am pretty sure no ecu wires should be hooked to it. Ecu should just be hooked to key on power or in your case a main power switch.


I eliminated the key altogether while trying to narrow down the problem. The "start signal wire" on the ecu gets a 12v "shot" when you turn the key. When you release the key, the 12v isn't at the ECU anymore. The starting button I have sends that signal when I press the button in but ceases when I let it go...similar to how the factory system works.

As for checking injectors with a light... the injectors have a 12V constant side and a signal side (ground pulse from ECU). If you take a test light and put it into the top of the injector harness plug while the key is on engine off, you will actually get a 12V (or light) on BOTH sides. That is why using a test light on injectors is no good. A noid light is needed to determine injector pulse. I used a noid last night and received no pulse.