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New 408 build won't start!!!

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Old Oct 1, 2018 | 01:02 PM
  #21  
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Originally Posted by FixMyJunk101
There should be a ground wire at the connector that grounds at the fuse panel. I cant remember off the top of my head what pin it is at the connector. A wiring schematic would be useful. Do you know what reluctor wheel is on your new engine? In 2006 they went from a 24 tooth to a 58 tooth wheel to enhance the crankshaft resolution. If your new engine has a 58 tooth reluctor wheel on the crankshaft the old pcm wont work. Also there is cheaper ob2 readers that will tell you the sensor values. You just cant do tests or activate anything like a scan tool would do. There's a book written by Josh Potak called How to Build and modify GM LS-Series Engines. Look into it if you get a chance.
as far as I know all my grounds are hooked up and then some. As for the reluctor wheel mine is a 24 which is what was in the car before so that shouldn't be an issue.
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Old Oct 2, 2018 | 08:19 AM
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Update still nothing I'm only getting what looks like .08 bolts to the injector if that's even right. What could be going wrong?
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Old Oct 2, 2018 | 12:24 PM
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You should have battery voltage at one wire with the key in the run position and the ecm/pcm will send ground to activate the injector when all enable criteria is good. Can you hear them click? Did you do an ohm test? Check all fuses and relays as well. Do you have good oil pressure when cranking the engine?
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Old Oct 2, 2018 | 02:34 PM
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Originally Posted by FixMyJunk101
You should have battery voltage at one wire with the key in the run position and the ecm/pcm will send ground to activate the injector when all enable criteria is good. Can you hear them click? Did you do an ohm test? Check all fuses and relays as well. Do you have good oil pressure when cranking the engine?
yes oil pressure is fine and I have no ticking or anything. When I test the pink wire to chassis ground I only get .08 volts with the key to the on position. I live alone and don't know anyone to try to start it while I check for voltage. Also i smell no gas Coming from it so I assume nothing is coming out. And ohms seem to be about 11 is that right maybe I did it wrong. But I don't think anything is wired wrong. When I text for continuity it doesn't beep when I put a lead on the head grounds and one on the chassis ground 2 feet from it. Also oil pressure switch is working and I can here the iac motor so again I don't think its electrical at all. Fuses are good and so are relays. Doesn't appear to be vats related either as the light stays off.
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Old Oct 2, 2018 | 04:01 PM
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New update only getting 1.2 volts across the injector fuses. Idk why
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Old Oct 3, 2018 | 03:55 PM
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Check your ground wires for excessive resistance. I've seen brand new cables be junk. With the key in the run position (not cranking) you should have 12 volts supplied to the injector. The other wire is the ground controlled by the pcm/ecm. Also specs for a 28lb injector which is what I have is 10 to 14 ohms. Im not sure if that changes with different injector sizes. I would say they are good. Did you test voltage at the fuse with the fuse installed and the key on. If so you are measuring voltage drop which indicates excessive resistance in the circuit. Voltage drop testing is your best friend when it comes to diagnosing electrical faults. You may have everything hooked up correctly but given the age of your wiring its possible that during the engine swap something was rattled and isn't supplying enough current. Broken wires are not always visible. They can break internally without breaking the insulation. Connectors having corrosion can damage the terminals and can require replacement. Not always visible but voltage drop testing will show you. Always back probe a connector. Shoving the dmm leads into the terminal can of a connector can bend the terminal causing poor contact when you reconnect. Make sure your battery is fully charged while testing or your readings will be inaccurate. I wouldn't use the chassis as a grounding point. The battery is the best ground point. Put the red lead on the positive post of the battery and move the black lead to your ground points of contact. If you don't see battery voltage or very close to it then that cable has poor contact excessive resistance. If you are 100% sure all wires, connectors, grounds and circuits are complete you could try a global reset. Remove all power sources (battery, amp capacitors) and connect the positive battery cable to the negative battery cable for about five min. As long as the cables have good contact with the electrical system it will drain all the capacitors in the modules and will reset your modules back to the factory setting as if it came off the factory line and never been started with a new engine. It will reset everything including an alarm, key code etc. Everything! Kind of a last resort.
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Old Oct 3, 2018 | 06:21 PM
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Originally Posted by FixMyJunk101
Check your ground wires for excessive resistance. I've seen brand new cables be junk. With the key in the run position (not cranking) you should have 12 volts supplied to the injector. The other wire is the ground controlled by the pcm/ecm. Also specs for a 28lb injector which is what I have is 10 to 14 ohms. Im not sure if that changes with different injector sizes. I would say they are good. Did you test voltage at the fuse with the fuse installed and the key on. If so you are measuring voltage drop which indicates excessive resistance in the circuit. Voltage drop testing is your best friend when it comes to diagnosing electrical faults. You may have everything hooked up correctly but given the age of your wiring its possible that during the engine swap something was rattled and isn't supplying enough current. Broken wires are not always visible. They can break internally without breaking the insulation. Connectors having corrosion can damage the terminals and can require replacement. Not always visible but voltage drop testing will show you. Always back probe a connector. Shoving the dmm leads into the terminal can of a connector can bend the terminal causing poor contact when you reconnect. Make sure your battery is fully charged while testing or your readings will be inaccurate. I wouldn't use the chassis as a grounding point. The battery is the best ground point. Put the red lead on the positive post of the battery and move the black lead to your ground points of contact. If you don't see battery voltage or very close to it then that cable has poor contact excessive resistance. If you are 100% sure all wires, connectors, grounds and circuits are complete you could try a global reset. Remove all power sources (battery, amp capacitors) and connect the positive battery cable to the negative battery cable for about five min. As long as the cables have good contact with the electrical system it will drain all the capacitors in the modules and will reset your modules back to the factory setting as if it came off the factory line and never been started with a new engine. It will reset everything including an alarm, key code etc. Everything! Kind of a last resort.
im at my wits end here I have no power going to coils or injectors every wire is fine and I did the battery thing. All sensors are reading according to obd. But I have no spark or fuel. The fuse doesn't have a constant 12v on run only when I crank it. When its in run I only get 1.5volts wtf could be happening.
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Old Oct 3, 2018 | 06:24 PM
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Or take your pcm and get it flash programed. Its easier than a global reset. It doesn't reset everything just the stuff that would prevent engine start up
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Old Oct 3, 2018 | 08:07 PM
  #29  
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Your pcm still thinks you have the old engine in it. The adaptive strategy used by the pcm accounts for wear and tear and changes fuel trim and ignition timing. Even if you did get your engine to start up it probably wouldn't idle right or idle at all. Most everything I have read about ls swaps mentions flash programming the pcm. I don't think its uncommon to do it.
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Old Oct 4, 2018 | 11:18 AM
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Without reading the whole thread, is VATS off? Must be disabled on swaps
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Old Oct 4, 2018 | 03:45 PM
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Originally Posted by Darth_V8r
Without reading the whole thread, is VATS off? Must be disabled on swaps
yes vats is off
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