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I am having a problem with my 94 3.8... The #6 injector blows fuel for a couple seconds as soon as you turn the key on then stops. Then as soon as you crank it, the injector blows wide open, the other injectors are fine only #6 is acting up.

I have played musical chairs with the injectors and it's not the injector... it's coming from the circuit it's plugged into.

I was curtain it was the PCM so replaced it with a remaned unit but it was the same thing.
I then started tracing the wire back to the PCM and ran a new wire to see it had been shorted but still the same thing.
All the injectors have 12V and the only thing I have found is some corrosion in the bulkhead fitting at the firewall.

I am going to try to clean the bulkhead connector and see if that will help.

I need help.
 

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Because the pulsed signal to the injector is a ground signal and it clears up ,I would definitely look at the connector for some type of corrosion creating resistance to affect the circuit.Have you used on ohm meter to check for resistance on #6 pulsed ground?Pull the connector off of the injector to check.Maybe compare it to other cylinders also.Not sure why it clears on its own though.
 

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I have just dealt with this sort of issue too. Sent the re-maned PCM back for another....the problem went to another cylinder....turns out, I had a bent pin in the bulkhead connector. We straightened it and now the car works like a charm! In fact, I have the original PCM back in the car that came with it from FORD. So that validated that I have had this problem from the assembly line! Good luck! It only took me 17 years to find my electrical gremlin....
 

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Discussion Starter #4
Because the pulsed signal to the injector is a ground signal and it clears up ,I would definitely look at the connector for some type of corrosion creating resistance to affect the circuit.Have you used on ohm meter to check for resistance on #6 pulsed ground?Pull the connector off of the injector to check.Maybe compare it to other cylinders also.Not sure why it clears on its own though.

I bypassed the connector by running a new wire from the PCM straight to the injector... but still the same thing.

Pulling my hair out. LOLfacepalm.gif
 

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Did you completely remove old wire from the injector,pcm ,bulkhead connector,harness,etc. Or did you just parallel the wire leaving a section of the old wire still connected in the circuit.If you completely removed old wire from circuit and with the pcm replaced ,the only area I can think of would be the pcm connector and that wire maybe cross connecting with another pin somehow (corrosion,etc.)Its where I would look with everything else being done.
 

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Discussion Starter #6
Did you completely remove old wire from the injector,pcm ,bulkhead connector,harness,etc. Or did you just parallel the wire leaving a section of the old wire still connected in the circuit.If you completely removed old wire from circuit and with the pcm replaced ,the only area I can think of would be the pcm connector and that wire maybe cross connecting with another pin somehow (corrosion,etc.)Its where I would look with everything else being done.

I cut the wire lose at the injector, then cut the wire at the PCM plug and ran temporary wire that is not connected to anything in the wiring harness. I did not strip the old wire out of the harness.

The plug on the PCM looks perfect, no corrosion, nothing bent.

Thanks Hockeyman for your time.
 

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Discussion Starter #7
We cleaned the bulkhead plug with contact cleaner and a wire brush, cleaned up nicely but it made no difference.

Is there anything else that could set off an injector like that or cause the ECM to?
 

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Even though you swapped the injectors ,I'd replace it and see what develops.Never know,it could be grounding itself internally(not sure if its a dielectrically insulated part or if the housing has some metal which could create an internal ground somehow to the block/fuel line/etc.).That's all I can think of to do.Not sure why the problem would not move with injector move but stranger things have happened.
 

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Discussion Starter #9
I put the #5 injector that was working perfectly in # 6 and it started acting up too. I have a set of noid lights on the way form eBay and I'm hoping they will narrow things down. They would not possibly be grounded to anything so it would be a good tell.
 

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doesn't that reveal the answer to the problem? when you moved the injector, the problem followed the injector. so the injector is the culprit.
 

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Discussion Starter #11
No Mark, the problem stayed with the #6 circuit and the bad injector that was switched to #5 circuit worked perfectly.
 

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oh i get it, misunderstood.
 

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It's got me stumped Mark, I have a set of noid lights now to give a try and maybe that will tell me something.

I keep hoping that someone that has had the same thing will let us in on what they found.
 

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It's got me stumped Mark, I have a set of noid lights now to give a try and maybe that will tell me something.

I keep hoping that someone that has had the same thing will let us in on what they found.
I found that the problem with the NOID lights on that side of the engine is that you need to have the plenum re-installed in order to run the car, hence rendering the NOID lights useless because they're underneath of the plenum. I used an Automotive Oscilloscope on the wire after the bulkhead. This revealed that the PCM appeared to not be putting out (flat lining), when in fact it was...then we found the faulty bulkhead. All I am saying is that working on that side of the engine is a PITA, especially if you have NOID lights underneath the plenum. Good luck!
 

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Only two things to cause this are a bad ecm or a short to ground on ground circuit.just went through this it was a bad re-man ecm..check groung wire unpluged from injector and ecm no ground plug ecm bsck in switch on and see if ground driver in ecm is staying on. Mine was on #four and #five injector
 

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Discussion Starter #16
Only two things to cause this are a bad ecm or a short to ground on ground circuit.just went through this it was a bad re-man ecm..check groung wire unpluged from injector and ecm no ground plug ecm bsck in switch on and see if ground driver in ecm is staying on. Mine was on #four and #five injector

Thanks Ally,

After pulling all my hair out and checking and double checking everything I could think of, I returned the ECM for another unit.

They tried to give me a hard time returning it... seems the remaned units have a remaned stamp on them and this one didn't. I believe they let someone pull a fast one on them and It got dumped on me.

Anyway... #6 injector is pulsing as it should now. Time to put it back together now.


Thanks to everyone.


Earl
 

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Discussion Starter #17
Got it back together and running better than ever... even fixed a problem with the IAC too.

thanks again to everyone.


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