Mikes67

I have a 67 Camaro with an LS1. Engine,harness, ECU are out of a 2000 Trans Am. I just started it for the first time. I had it running about 15 minutes. Went to start it again and found my injectors are not firing. I put noid lights in the plugs and found if I move the harness going through the firewall to my ECU they would fire. I have 12 volts at each injector. It would seem that I have some sort of connection problem. I pulled the blue plug and checked continuity for the ground wires. That was fine. What wire or wires share a common bond with the injectors?

1964SS

iTrader: (1)

The only common connection is the power itself for each bank. Each injector is grounded by the pcm control. If you've got power then I would check for faulty pcm grounding.

Mikes67

That's what I thought too, but I have continuity at both ground pins of the plug.

the_merv

iTrader: (88)

Check the 12v side also, and then check when you move the wires to see if it drops power or ground. Not sure how you have it all spliced or wired. 12v side is split to each injector and coil pack bank, per side.

Mikes67

So I rechecked my voltage at the injectors again. My battery was at 11.7 volts. Each injector had 11.6 volts. Also checked when I cranked and everything stayed the same. My battery was getting low when I checked the signal. Each injector had around 9.6 volts while cranking.

the_merv

iTrader: (88)

Try a different battery or have it load tested.. might be a bad cell.
Hard to say without seeing the car how you have it wired. I ground everything, like double and triple grounds with 00 Cable

Mikes67

It's a brand new odyssey battery. My main ground wire is 1 gauge if I remember correctly. Both heads grounded,block grounded frame grounded multiple places. I was **** about grounds...

truckdoug

iTrader: (25)

sounds like you got a couple things going on at once. i wanna see 12.5 in any decent battery. 11 volts can make ecm triggered relays act funny.

but a .1v drop to the injector aint bad.

what kind ohm drop do you get on the injector control circuit (from the injector to the ecm) ? affix your probes to each and and wiggle the harness and see of you lose continuity.

how's it run with a jump box connected?

the_merv

iTrader: (88)

Dropping to 9.6 when cranking tells me a bad cell.. new or not it can still be ****. Get it load tested.

Mikes67

So with untaping the harness and moving things around I can no longer get the noid lights to light when I crank it over. I did check continuity on all 8 injector wires and had a reading of 0 on all of them. I checked all of the wires on the blue ecu plug and have continuity to every one of them at their destination.

the_merv

iTrader: (88)

So from the plug to the injectors on the PCM wires you have 100% continuity... sounds like the 12v side has a bad splice in it.

Mikes67

That was one of the first things that I checked. I definitely have a good constant 12 volts at the injectors both with the key on and with cranking.

Mikes67

So I checked the voltages on the pins in the picture. I have the values written along side of them. Not sure what pin#3 for the injectors should be? Pin#15 on the red connector, for the generator turn on signal seemed low too. I couldn't find what these values should be.

gagliano7

Are you sure vats is disabled in the tune? Have you charged the battery to full charge and try cranking?

Mikes67

I ran it for about 15 minutes when I first fired it up. Battery is over 12 volts right now and get nothing.

Mikes67

Mystery solved. It runs! Broken signal wire for the crank sensor.

truckdoug

iTrader: (25)

how do you you troubleshoot it to that? no rpm when cranking?

Mikes67

I pulled the starter and checked the resistance on the crank sensor, obviously good. Put everything back together, when I cranked it over the noid lights lit. Had my buddy crank it over, moved the wires and they stopped. Pulled it apart and removed the conduit and found the signal wire damaged about 2 inches from the plug.

truckdoug

iTrader: (25)

nice work. thats tough to find them intermittent ones