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Electronic Oddity, any in depth ideas?


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180 replies to this topic

#1 koolminx

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Posted 03 January 2018 - 07:30 PM

Have myself a 95 Legacy Brighton....  Auto trans blah blah, 2.2l yadda yadda....

 

Most times when cranking there is ZERO signal to the Injectors...   As she sits, the car will only start when the cranking voltage draws the starter down to a crawl, and sometimes not even then...

 

When I utilized a Noid light, it shows ZERO illumination, when it is supposed to be flashing with each signal from PCM, thus the car will not fire off.  sometimes when cranking with the Noid light in injector 2's slot, the light will flash and the car immediately starts.  Other times the Noid light will be dark during cranking and only flash once when the key is Released from the crank position, and the next attempt to crank it, it WILL start....   

 

Therein lies my constitutional dilemma....

 

 

This issue was in place before I replaced the physical ignition switch from a running driving problem free Legacy.

 

The car starts better after it's been run and is up to temperature --on occasion--

 

Not the fuel pressure, I have 36 psi.

Not filter, it's new and free flowing.

Not the crank sensor, NEW and crank wheel is dust and debris free.

 

 

With only a 4 wire ignition switch, it is not the ignition switch in my opinion.

But....   I've been wrong once before, and that was the only time...  lol   8)

 

What is the next step guys and gals?

 

The PCM is going to be unplugged, and I am going to clean and apply electrical connection lube and cleaner before reconnecting.

 

What is my mostly dim but brilliant mind missing in this setup?

 

Thank you for your time and hopefully BRILLIANT replies 8)



#2 sparkyboy

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Posted 03 January 2018 - 07:51 PM

I actually have this same damn problem with my ej22
Might have something to do with the coolant temp sensor, but i just let her fight until she stops acting stupid and starts. She has started un -7 once acting like a total c**t, but after warming up starts easily.
Just run her often, i find mine starts easily if she was driven the night before, or warmer than 15*

Edited by sparkyboy, 03 January 2018 - 07:56 PM.


#3 koolminx

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Posted 03 January 2018 - 07:58 PM

I actually have this same damn problem with my ej22
Might have something to do with the coolant temp sensor, but i just let her fight until she stops acting stupid and starts. She has started un -7 once acting like a total c**t, but after warming up starts easily.
Just run her often, i find mine starts easily if she was driven the night before, or warmer than 15*



#4 koolminx

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Posted 03 January 2018 - 07:59 PM

Well that sounds like a nice idea although I have no idea what the coolant temperature sensor would have in relations to the ECM sending a pulse for the injectors no matter what temperature the injectors should always receive their pulse while cranking and running

#5 GeneralDisorder

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Posted 03 January 2018 - 08:10 PM

Check the bulkhead harness connectors between the manifold and body harness. Not unusual to see corrosion on the pins. Also check the ground points on the manifold, and then look at if you are losing the ground signal from the ECU or the 12v injector supply voltage.

 

Could also be cam/crank sensor signals or a faulty ECU (check inside for moisture or corrosion) But check injector wiring first. 

 

GD



#6 koolminx

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Posted 03 January 2018 - 08:12 PM

All of the connections to the engine from the fireball have been checked but I will double check them tomorrow and I will reassemble with Dielectric grease that's another good idea although they were inspected in all appeared to be in good condition

#7 GeneralDisorder

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Posted 03 January 2018 - 08:15 PM

My bet is on the ECU being faulty. Open it and check for any moisture. I've seen a number of them die and it's almost always the injector driver's that give out. 

 

GD



#8 koolminx

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Posted 03 January 2018 - 08:17 PM

That'll be done first thing tomorrow thank you for that thought!

#9 Fairtax4me

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Posted 03 January 2018 - 09:15 PM

No check engine codes?
Cam sensor gives the command for fuel injection timing IIRC.

#10 koolminx

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Posted 03 January 2018 - 09:23 PM

The only time I get a check engine light is when I disconnect something and start the car it will set a fault code for the injector that I plug the Noid light into and if I disconnect the crank sensor and crank the motor over it immediately set a code for the crank sensor otherwise there are no codes

#11 koolminx

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Posted 03 January 2018 - 09:23 PM

Plus I will check the cam sensor if I can find somebody that will tell me where they're located :-)

#12 Fairtax4me

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Posted 03 January 2018 - 09:27 PM

Only one. Left side behind the plastic timing cover. Plug sticks out kinda below /in front of the oil filler tube.
Normally bad cam sensor will set a code.

Edited by Fairtax4me, 03 January 2018 - 09:28 PM.


#13 koolminx

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Posted 03 January 2018 - 09:29 PM

Sure you're not talking about the crank sensor or does it have a crank sensor and cam sensor both?

#14 Fairtax4me

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Posted 03 January 2018 - 09:32 PM

Has one crank sensor, and one cam sensor.

#15 koolminx

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Posted 03 January 2018 - 09:34 PM

Thank you I will get on that first thing as well remove it clean the connections and see what goes on

#16 koolminx

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Posted 04 January 2018 - 08:03 PM

The cam sensor is fine the wiring to the cam sensor is fine there are no check engine lights the car just cranks and cranks and cranks and does not get signal to the injectors anymore except right as you let off the key the last rotation will send a faint pulse to the Noid light somebody needs to be able to crack this code

#17 koolminx

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Posted 04 January 2018 - 08:22 PM

I need brilliance...

What prevents the injectors from getting a pulse from the ecm during cranking?

Just an overall bad ecm? And if so.... what are some compatible subarus to test anotger ecm from?

#18 sparkyboy

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Posted 04 January 2018 - 10:12 PM

That is a wacky problem indeed, is the main relay related to fuel injectors? You might be able to supply 12v at the ecu to see if the injector stays open.
Unfortunately the 95 had a one year only ecu. 96 has the same connector, but pins for 12v and what not are in different locations.

Edited by sparkyboy, 04 January 2018 - 10:28 PM.


#19 keith3267

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Posted 05 January 2018 - 12:20 AM

I don't believe you get pulses during cranking save for a large pulse at the very beginning.  If it kept pulsing the injectors during cranking, it would flood the engine.  Some older cars had a special injector called a cold start injector, I don't think those are used any more.



#20 GeneralDisorder

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Posted 05 January 2018 - 02:35 AM

You can only use another 95 ECU. It's completely distinct and one year only.

The behavior of it sounds like potentially a faulty ignition switch. Basically it's not sending power to the ECU when cranking. Only when in the run position. Thus the brief injector pulse while the engine is spinning down as you release the switch back to run.

Check all your 12v inputs to the ECU with the ignition switch in both run and start.

GD

#21 sparkyboy

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Posted 05 January 2018 - 03:03 AM

If it is the ignition switch couldn't you turn the switch to run and touch the starter solenoid with a screwdriver or piece of wire? I would think she would start right up. Then you can wire in a push button or switch and your car will be a lot harder to steal, I have had my 92 stolen once.

Maybe if you have someone to help you can take a power probe and supply 12 volts at the harness and see if the noid light lights up.


Edited by sparkyboy, 05 January 2018 - 03:11 AM.


#22 koolminx

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Posted 05 January 2018 - 09:12 AM

I don't believe you get pulses during cranking save for a large pulse at the very beginning. If it kept pulsing the injectors during cranking, it would flood the engine. Some older cars had a special injector called a cold start injector, I don't think those are used any more.


The injector must get a pulse at every revolution of compression otherwise the engine will not run......

#23 koolminx

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Posted 05 January 2018 - 09:14 AM

If it is the ignition switch couldn't you turn the switch to run and touch the starter solenoid with a screwdriver or piece of wire? I would think she would start right up. Then you can wire in a push button or switch and your car will be a lot harder to steal, I have had my 92 stolen once.
Maybe if you have someone to help you can take a power probe and supply 12 volts at the harness and see if the noid light lights up.


The car was originally wired very similar to that had a toggle switch for the start to crank signal but even then the car was failing to start for me so what I will do is I will find out what my ignition Powers up initially and trace it from there I guess. I took the ECU out yesterday and I inspected every square inch and nothing seems to have ever been overheated all the circuits are in fantastic appearing condition.

#24 koolminx

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Posted 05 January 2018 - 09:15 AM

You can only use another 95 ECU. It's completely distinct and one year only.

The behavior of it sounds like potentially a faulty ignition switch. Basically it's not sending power to the ECU when cranking. Only when in the run position. Thus the brief injector pulse while the engine is spinning down as you release the switch back to run.

Check all your 12v inputs to the ECU with the ignition switch in both run and start.

GD


Out of the four wires in the ignition switch which one sends power to the ECU I can trace everything from that point forward

#25 GeneralDisorder

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Posted 05 January 2018 - 11:15 AM

I would have to consult the diagrams. Download the manual here:

https://sl-i.net/FOR...ervice-Manuals-(FSM)-Every-Model-USDM-EU

It is not sufficient to just turn the starter - the ECU also needs a 12v signal from the starter solenoid lead telling it you are cranking the engine.

GD

Edited by GeneralDisorder, 05 January 2018 - 11:18 AM.





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