Engine Swap - Now No Injector Pulse

[Brook24v]

93 ATX - 200k+ on body. Swapped in an engine with low mileage.

As title says my ATX just got all bolted back up and ready to start, but there is no injector pulse. It has spark, it has fuel, all key on engine off tests pass, the cam position sensor checks out okay, I've replaced the ignition module, replaced the computer, and kinda looked around for anything unhooked. I can't figure it out. What else would control injector pulse? I have a feeling this is going to get ugly.

:cry::cry::cry::cry::cry:

 

[Phoenix]

Theres a ground in the channel valley , on the block , do you remember installing it?

 

[Brook24v]

Oh shit. I'm not sure if that got hooked up or not. Where does it ground off to (from the valley)?

Thanks for the quick reply, Phoenix.

 

[Brook24v]

That wouldn't explain the no pulse though?

 

[zblackbeast]

Is it firing batch or not at all?

 

[Brook24v]

Theres a ground in the channel valley , on the block , do you remember installing it?

Nevermind. It is hooked up. Thanks!

Is it firing batch or not at all?

It fires 1 bank at a time, not per cylinder. Which would be sequential.

It has power. There is just no on/off signal from the PCM.

 

[zblackbeast]

So its firing batch.. I would look at you cam sensor.. I can't remember what other sensor controls the sequential which ****** me off because we read it when we were solving tims no fire issue..

 

[Brook24v]

Ya I don't know what to think about that cam sensor. You can probe it and it reads fine.

 

[zblackbeast]

Either way, the car should still run without the cam sensor.. just hard to start.. Does you car run?

EDIT: Maybe a bad/wrong CCRM?

 

[Brook24v]

It will not start. It ran and drove before the new motor though! !!

A quick search tells me the Constant Control Relay Module is responsible for:

1) EEC Power Switching
2) Fuel Pump Relay Switching
3) Cooling Fan Power Control
4) A/C Clutch Control

Doesn't sound like it would have anything to do with a lack of an on/off injector signal from the PCM.

 

[Phoenix]

Out of the blue , just make sure the DIS has all its 4 bolts , only 3 may cause a no-start. Same with the ground strap behind the intake.

 

[LJRuddy]

It has been my experience that not having a working cam sensor, crank sensor, DIS or ground strap will only prevent spark and not fuel.

 

[Brook24v]

Will do.

Edit: Ninja'd.

 

[Brook24v]

It has been my experience that not having a working cam sensor, crank sensor, DIS or ground strap will only prevent spark and not fuel.

Which makes me believe something with the wiring has to be wrong. If the computer is doing everything it should and sending an impulse signal to the injectors.......... WHERE DID IT GO?!! You wouldn't think any connectors on that harness got switched around and plugged into the wrong thing? Or does that signal pass through something else before hitting the injectors?

This sucks.

 

[Brook24v]

Is there any kind of a power relay for the injectors? Maybe I'm missing something stupid simple here. Or do these cars have some kind of signal from the ignition inside the car when you turn the key on? The last time I started this car (with the old engine) was sometime in 2008. Maybe the ignition took a shit? I'm just typing whatever my brain is grasping at now....

 

[jonheese]

The actual electrical signal to fire the injectors comes straight from the ECU, but the timing and duration of the signals are determined using information gathered from a few different sensors (cam sensor, crank sensor, MAF sensor, etc.).

Since your injectors are firing in batch mode, that means that you definitely have a good +12V and (switched) ground at the injector harness.

Have you checked for DTCs? I honestly can't think of any failure that would cause this kind of symptom and not set a code. It sounds like the ECU is not getting some kind of timing signal and is therefore unable to fire the injectors sequentially, and that should definitely set a code.

 

[jonheese]

Which makes me believe something with the wiring has to be wrong. If the computer is doing everything it should and sending an impulse signal to the injectors.......... WHERE DID IT GO?!! You wouldn't think any connectors on that harness got switched around and plugged into the wrong thing? Or does that signal pass through something else before hitting the injectors?

This sucks.

The signal to fire the injectors comes directly from the ECU to the injectors. The injectors get +12V on one pin at all times when in "run", and the ECU actually switches the ground in order to fire each them. Should be a straight shot from the ECU to the injectors (via the main harness and injector harness, IIRC).

ECU pin numbers are as follows:
Cyl 1: pin 58
Cyl 2: pin 59
Cyl 3: pin 39
Cyl 4: pin 35
Cyl 5: pin 15
Cyl 6: pin 12

Is there any kind of a power relay for the injectors? Maybe I'm missing something stupid simple here. Or do these cars have some kind of signal from the ignition inside the car when you turn the key on? The last time I started this car (with the old engine) was sometime in 2008. Maybe the ignition took a shit? I'm just typing whatever my brain is grasping at now....

Yes, the injectors are powered from the "hot during run" circuit (which originates from the ignition switch), but if the injectors are batch firing, you've got power. You can verify this by unplugging the electrical connector on one (or more) of the injectors and probing for voltage with the key in the run position. You should get 0V on one pin (the switched ground) and +12V on the other.

 

[LJRuddy]

Have you checked for DTCs? I honestly can't think of any failure that would cause this kind of symptom and not set a code. It sounds like the ECU is not getting some kind of timing signal and is therefore unable to fire the injectors sequentially, and that should definitely set a code.

It will be impossible to pull codes from an engine that has never ran. :wave:

 

[jonheese]

It would? Why does it matter if the engine's run or not?

I was under the impression that the code gets set as soon as the fault is detected. If the ECU is knowingly firing the injectors in batch mode, you can be damn sure it's detected a fault.

I would think KOEO would tell you what you need to know.

 

[LJRuddy]

Ive never been able to get a code from just cranking the engine over. Unplug your cam and crank sensors and try to start it. You wont get any codes at all.