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Something is cooking ECMs by Slammed
Started on: 05-15-2015 12:43 AM
Replies: 12 (265 views)
Last post by: AL87 on 05-16-2015 01:31 AM
Slammed
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Report this Post05-15-2015 12:43 AM Click Here to See the Profile for SlammedClick Here to Email SlammedSend a Private Message to SlammedEdit/Delete MessageReply w/QuoteDirect Link to This Post
3 ECUs have died. I have about 1.6v AC voltage coming from the distributor reference, but no injector pulse and no RPM in WinALDL. RPM gauge shows crank. Strong spark. Solid check engine light with key on and it will blink codes

If I tap 12v to the reference wire coming from the distributor, the ECM will cycle the pump but not pulse the injector

What would cause the RPM sensing circuit or injector driver to fail? I am at a total loss

I have good grounds and have voltage where it needs to be on all ECM pins

[This message has been edited by Slammed (edited 05-15-2015).]

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AL87
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Report this Post05-15-2015 01:24 AM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
Hello, sorry to read the trouble you're in, electrical is a nightmare to have to trace.

I'd check your fuse box for anything with a higher-amp fuse than what is needed.
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Slammed
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Report this Post05-15-2015 01:48 AM Click Here to See the Profile for SlammedClick Here to Email SlammedSend a Private Message to SlammedEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have pulled and replaced all the fuses and have been through the entire engine harness
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Slammed
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Report this Post05-15-2015 02:41 AM Click Here to See the Profile for SlammedClick Here to Email SlammedSend a Private Message to SlammedEdit/Delete MessageReply w/QuoteDirect Link to This Post
What is the minimum the ECM needs to pulse injector? Can I wire it up on the bench with 12v and grounds, and bump the reference to get injector pulse? Or does it need more?

It was popping the ECM/INJ fuse. Isn't anymore and it is supplying power.

If I tap 12v to the reference, I get RPM data, but no injector fire still. Turning over yields no RPM data

Edit: Ok, now out of nowhere it'll flash my noid light. Very dim. Not enough voltage to click the injector or just really short duty cycle on crank? Bad brand new injector?

[This message has been edited by Slammed (edited 05-15-2015).]

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Raydar
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Report this Post05-15-2015 06:21 AM Click Here to See the Profile for RaydarClick Here to Email RaydarSend a Private Message to RaydarEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Slammed:
...
It was popping the ECM/INJ fuse. Isn't anymore and it is supplying power.



Stock configuration?

This may be a "tangent", but one of the INJ fuses also supplies the EGR solenoid. If that solenoid shorts, it'll take out the fuse.
Runs like kwrap on 3 cylinders.

Edit - You know that the supply voltage to the injectors is constant, and the ECM injector driver switches ground... right?

[This message has been edited by Raydar (edited 05-15-2015).]

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Slammed
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Report this Post05-15-2015 08:23 AM Click Here to See the Profile for SlammedClick Here to Email SlammedSend a Private Message to SlammedEdit/Delete MessageReply w/QuoteDirect Link to This Post
Yes. And yes.

This is in an 84, so only the one ECM/INJ fuse. No 5 amp INJ fuses

[This message has been edited by Slammed (edited 05-15-2015).]

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ag9123
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Report this Post05-15-2015 10:13 AM Click Here to See the Profile for ag9123Click Here to Email ag9123Send a Private Message to ag9123Edit/Delete MessageReply w/QuoteDirect Link to This Post
Check the Ogre's Cave regarding the ECM insulation while your in there. Removing it helps the ECM cooling.
http://home.comcast.net/~fierocave/ecmheat.htm
------------------
1984 Indy Fiero

[This message has been edited by ag9123 (edited 05-15-2015).]

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phonedawgz
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Report this Post05-15-2015 10:39 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
One of the three injectors on that fuse is shorted.
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theogre
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Report this Post05-15-2015 10:43 AM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
ECM Heat is bad but likely isn't the main problem.

84 are good at having alt wire problems that can cause alternator problems. Have to do how 84 is wiring.
See my Cave, Alternator Sense

Check the alternator at most part stores... Bad SI alt can push AC volts and kill ECM etc. Bad alt can be over volt on DC and kill things. 84 doesn't have an alt/battery light that give some warning when alt is bad.

Could be have a bad injector and frying ECM driver and/or blow the fuse.

Power/ground problems can cause low volts to some parts and not others. Low Volts will cause many parts to draw more amps to make up the watts needed by motors and coils.
See my Cave, Electric Motors

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)


The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

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Gall757
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Report this Post05-15-2015 11:07 AM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by phonedawgz:

One of the three injectors on that fuse is shorted.


Advice for V6 owners. I have never heard of a short in the Duke injector, but perhaps it happens.

[This message has been edited by Gall757 (edited 05-15-2015).]

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phonedawgz
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Report this Post05-15-2015 12:48 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Measure the resistance of your injector and make sure it is within spec.
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Slammed
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Report this Post05-15-2015 01:43 PM Click Here to See the Profile for SlammedClick Here to Email SlammedSend a Private Message to SlammedEdit/Delete MessageReply w/QuoteDirect Link to This Post
New injector is bad. I checked the resistance before I put it in and it was right at 1.5ohms. Wonder what happened...

I have a feeling it won't be the end of this, I can't imagine it just failed being plugged in. Finger crossed

[This message has been edited by Slammed (edited 05-15-2015).]

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AL87
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Report this Post05-16-2015 01:31 AM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Gall757:


Advice for V6 owners. I have never heard of a short in the Duke injector, but perhaps it happens.



I have never heard of it either, last time I had an injector short, I put in a fuse 10amps more than what it was rated for, ran like a champ until the injector took a dump, without blowing the fuse, I then used a looong pigtailed injector connector and "tapped" all 6 injectors until I found out which one wasn't clicking, and then replaced it.

its hard to troubleshoot injector problems unless the injector goes, I usually test ALL injectors by supplying direct power from a battery holding them open at various lengths of time until I am satisfied they wont pop, or if they do pop, to replace them accordingly.

I had one pop in my hand after applying current to it for 5 seconds after it stopped clicking when I was tapping the battery terminal with the pigtail to test. it looked akin to a mushroom cloud...

EDIT: on a side note, I've come across perfectly fine fieros for CHEAP from people who don't know how to troubleshoot. Usually the first singular component I check when I have a fiero that isn't starting up is the ecm. I have found a pin or two on the ecms being fried at the base where they are soldered. My first experience with this was simply just unplugging the harness from the ecm, the harness connector still had the pin from the ecm stuck in it.

[This message has been edited by AL87 (edited 05-16-2015).]

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