Closed loop fault, injectors constantly firing, no signal tfrom ecm 6 inj

so! i 've been on a fun project. i really feel like its an ecm problem now… but! here ya go! (updated)

2006 buick lucerne v8 northstar

  • always constantly on closed loop

  • so injectors are firing in compression, intake, exhaust.

  • thick fuel coming from the tail pipe

  • all the injectors are firing. i listened to them with the stethoscope, they’re all clicking

  • i checked the ecm which is located with the air filter box assembly.

  • wire is good, not frayed or loose or corroded (might have to double check, was going to splice ground at this point)

  • receiving power and ground to injectors

  • noide light constant on injector 6

  • no ground reading found for pin 73 at ecm, middle connector

when the engine is cold it’s not as noticable. but when it warms up, that fault never goes away, and it stays in closed loop fault. starts running super rough, idling funny,

when driving, it still drives, still has power . but is reduced

Maybe ECM. But the cam and crank sensors work together to tell the ECM when to fire spark and injectors. It’s just a thought, but maybe you could check the sensors for proper gap and tone ring conditions.

Remove the connector for that injector and see if it’s getting voltage.

If it is, the driver in the ECM isn’t grounding that injector, which would mean the ECM is bad.


i thought about that as well, seeing how theres 2 cam sensors, it is possible one is being faulty

i don’t see why that injector still isn’t receiving anything

this i have done. and i probed the connector
i did this to others as well and only number 6 was still not reading

so if there’s nothing i can do about it.
still learning about everything as i go. this is quite the learning experience
, i suppose i’ll invest in a plug and play vin specific ecm online

I install used ECM’s from an auto recycler.


have you seen this as a problem before?
is there a way to test the ecm before possible saying that yes it is bad.

unless i already did that without knowing.

uhm just took my ohm meter to measure voltage to the ecm connector pin by back probing pin 70 fuel injector 6 control
which was the only one not receiving anything.

Maybe a bad connector for injector #6.


alright found and solved this issue. found frayed wiring under the intake , wiring harness running across was frayed. plastic was frayed. and i found a few wires that were about to get cut.
one thing done! onto engine reduced power now… thank gm! XD

Are you sure you had the noid light on the “load” side of #6 injector? Otherwise, something is amiss here. The injector is audibly clicking, has ground and power but the noid light is not flashing like the others?

If this is the ground reference point, this is where you should start. How did you establish “no ground reading”?

so i found out that there was a few wires frayed. and if i moved and touched the wire jut right i would get readings. and sometimes i would wont. so i was stumped on why the hell i was getting signal and some times i was not. it wasn’t until i had the ecm taken out and i could freely move it around when i noticed the noide light went from a constant light and then it didn’t, and functioned just fine. had to clip wirings and resauder and reattach new ones.

but now that was only one problem solved
i’m still getting tranny codes. and a engine reduced power came up. lovellyyy gotta love this fun northstar.

once i established that i had a proper ground connection, i moved onto checking the wire that runs from the ecm to the injector. and that’s when i found the damaged wires. where the splice conjunction was under the air intake valve . there was also a motor mount that is damaged. so as the vehicle shifted gear and at start up, etc. would rock and shift the engine. eventually eating away at the protective plastic and eventually wiring.

Good progress! Might as well do a visual on all the wiring harnesses subject to engine movement, esp the transmission harness(es). Hopefully no electrical damage to the devices driving those lines and just have to fix the compromised insulation…

honestly at this point i’m getting these bloody tans codes. that the transmission cooler line has been leaking slowly. limp mode basically is on XD most of my issues has been wiring so far. i wouldn’t be surprised to find another wire or more frayed at the transmission as well.
abs codes for invalid serial data so it trips the abs light for some damn reason. but also a wheel speed sensor isn’t functioning properly. so that’s most likely the cause.

also a lovely p2534 code
and low engine reduced power popped on after repairing the wiring for the 6 inj.
i’m assuming the trans is a little low on fluid maybe that’s why the computer basically is in limp mode.
high shift points but still runs nicely…

valve covers need fixing soon.

the shop she went to before sorta did her dirty, but got these codes pulled that i never could find.,
c0045 (this one i got while messing around with my new diag computer, didn’t get a code for it but found one the tpms to not be functioning properly}
c0196 yaw rate malfunction test not passed
c0561 which was that abs code for invalid serial number. odd.

ugh gotta love this project. :3