Injectors 2&3 not pulsing

[chaggard27]

Ok I am completely stumped on this one. I have been troubleshooting sooo long I am doing it in my dreams. Here is the deal...I am working on a 99 gst auto that is not pulsing injectors 2 or 3 when running. While cranking engine the injectors pulse. Once the engine starts they stop and it runs on two cylinders. I have changed the ECU thinking that it could be an issue with leaking caps but no change. I have 12v to all connectors with key on. I changed the resistor pack, I ran a new wire from signal side of injector connector to respectable wire on ecu and nothing has fixed the issue. If I change the injector plugs the problem follows the plugs. I did a test by bridging inj 1 wire with inj 2 wire at ecu and same with 3 and 4 and the car then ran on all 4 with all the injectors pulsing. Problem solved right??? Not exactly how I want since this way it will use more gas since both injectors are pulsing on for each individual cylinder and I will run rich as far as smog. Also just to mention I have the nearly impossible to diagnose P0300 code. If I clear it then the car will start and pulse all 4 injectors right on startup and then it kills injectors 2&3. Any help will be GREATLY appreciated!

 

[Maverick4g63]

Just to clarify, your saying you've verified that that the ecu is or isn't pulsing 2 and 3 injectors?

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[chaggard27]

The ecu pulses both 2 & 3 while cranking but once the engine starts then the ECU stops pulsing 2 & 3.

 

[Tyeler18]

When you say it follows the injector plugs what do you mean? Do you mean that when you change say injector 2 with 4 that injector 4 stops pulsing now?

 

[chaggard27]

Yes that is exactly what I mean...sorry I couldn't think of a better way to word that.

 

[Tyeler18]

Have you replaced the injectors? If you put injector 2 in injector 4's place and that injector still won't pulse I can only assume that that injector is bad.

 

[chaggard27]

It actually follows the connector. If I switch 2 with 1 then injector 1 doesnt pulse but 2 does. I know injectors are good because like I said they all pulse when cranking the engine. The ECU just stops sending a signal to 2 & 3 when it starts. I am thinking is is CAS or Cranks sensor....since they are a pair and usually when there are two pair cylinders misfiring it is a sensor. Just need a second opinion before having this guy buy random parts. Even though it wouldnt hurt to get new crank and cam sensors

Also if I bridge the injectors then the engine runs fine and all four cylinders fire and all 4 injectors pulse. Just will burn through gas that way and the tach does not show correct since the ecu only sees two cylinders firing...

 

[tenn-gsx]

Try the transistor and cas.

 

[chaggard27]

Try the transistor and cas.

Are you talking about the power transistor? Because I get good spark so would that deal with the injectors as well?

So I decided to change out the crank position sensor and see if this solves the problem correctly or not. The CAS seems to be new so it should be ok. I may change it out with an extra I have to make sure and then I will let you guys know what I find out

 

[jaxiejess]

I know this thread is old but did you find out what was causing that to happen? I'm having the same issue but with cylinders 3 &4.

 

[SvarO]

friend of mine have the same problem, please input.

 

[boostwut]

im pretty confident its something to do with the ecu it self like a leaking cap or damaged circuit

 

[oneslowevo]

any updates on this? my friend is having the same exact issues

 

[asianandy87]

Please, any help with that?
i have a 91 tsi fwd, doing this but on top of this it wont start.