New 408 build won't start!!!
New 408 build won't start!!! My car doesn't have the transmission hooked up yet but the engine is in the car and as far as I know all the sensors are hooked up and all the grounds as well. Except the transmission stuff and the maf sensors. But my problem is I don't seem to have power to my fuel injectors or coils... I have pressure in the fuel rails and I checked and it's their. Now when a friend cranks it over the starter spins and turns the crank and stuff but it doesn't even start as if its getting fuel and spark their isn't anything. I checked the spark plugs and no power was in them. What could be wrong could it be because the trans isn't hooked up like a safety switch? If so how do I trick it till the trans is done at the build shop? Or am I missing something else any help would be apprectiated.
But how will the car know if it's in park or doesn't these cars do that? But I went back to the garage and have power head lights break lights all lights work. I have fuel as well. It seems when the gf turns the key I hear a grinding or clicking noise coming from the iac sensor is that normal? Or does it mean bad grounding. I have 1 gauge on both sides the engine plus the strap and the 3 behind the head. Does pcm need grounding? It was pulled through fire wall. Also fuel pump works i hear it priming. Also no pulsing for the injectors or spark still.
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Teching In
Joined: Sep 2018
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The only way the trans wouldn't let the car start is if the neutral safety switch wasn't sending the signal to the ecm to the starting circuit but since your engine is cranking that shouldn't be the cause. The maf could be the reason. Its supposed to tell the engine how much air is coming in so the ecm knows how much fuel to inject. A scan tool would tell you what the computer is seeing and give you a good direction. Check the cam and crank sensors again. They tell the ecm when to deliver spark and fuel.
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Verdad Gallardo The only way the trans wouldn't let the car start is if the neutral safety switch wasn't sending the signal to the ecm to the starting circuit but since your engine is cranking that shouldn't be the cause. The maf could be the reason. Its supposed to tell the engine how much air is coming in so the ecm knows how much fuel to inject. A scan tool would tell you what the computer is seeing and give you a good direction. Check the cam and crank sensors again. They tell the ecm when to deliver spark and fuel.
TECH Enthusiast
Joined: Nov 2016
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From: PNW
The neutral safety switch doesn’t prevent the engine from starting, it prevents the starter from starting the engine. The transmission being missing has absolutely nothing to do with PCM’s inability to fire the coils or injectors.
Did you connect all of the grounds in the harness to the engine? If you did, I would look at the cam and crank position sensors, the PCM may not know the engine is turning.
Did you connect all of the grounds in the harness to the engine? If you did, I would look at the cam and crank position sensors, the PCM may not know the engine is turning.
Teching In
Joined: Sep 2018
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if you have a scan tool or access to one you could check all the sensors very easily.Sometimes the connectors are the problem. loose, corroded or damaged prongs are something to check. Your ecm is shutting off the fuel and spark is my guess. Hope this helps yeah. Remember to not use a test light on anything computer controlled or you might have to refill your ecm with smoke.
if you have a scan tool or access to one you could check all the sensors very easily.Sometimes the connectors are the problem. loose, corroded or damaged prongs are something to check. Your ecm is shutting off the fuel and spark is my guess. Hope this helps yeah. Remember to not use a test light on anything computer controlled or you might have to refill your ecm with smoke.
I didn't know it had to be relaerned. I hate the fact that I'll have to take it to a shop for tune just to see if anything maybe wrong.
The neutral safety switch doesn’t prevent the engine from starting, it prevents the starter from starting the engine. The transmission being missing has absolutely nothing to do with PCM’s inability to fire the coils or injectors.
Did you connect all of the grounds in the harness to the engine? If you did, I would look at the cam and crank position sensors, the PCM may not know the engine is turning.
Did you connect all of the grounds in the harness to the engine? If you did, I would look at the cam and crank position sensors, the PCM may not know the engine is turning.
Teching In
Joined: Sep 2018
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Sorry I reread thru your post and noticed you asked if the pcm needs grounding. Absolutely it does. That's the input for all your sensors. All modules should be functioning. The pcm is your onboard diagnostics. it would set dtc's. Theres a cell phone sized scan tool that available on amazon for about $450 last time I looked at them. It would be better to just borrow one if possible. A scan tool wouldn't do much good if the modules are powered and communicating tho Relearning shouldn't need to be done if its the original modules and sensors. SInce you didn't swap the accelerator pedal it shoiuldnt have to be messed with but If the pedal is at 80% (pedal to the floor) and engine rpm less than 600 it enters a clear flood mode which would prevent the injectors from working. Pretty rare to have happen but you cant rule anything out. Sometimes the engine coolant temp can even cause a engine crank no start symptom. I would make sure your modules are working tho.
Sorry I reread thru your post and noticed you asked if the pcm needs grounding. Absolutely it does. That's the input for all your sensors. All modules should be functioning. The pcm is your onboard diagnostics. it would set dtc's. Theres a cell phone sized scan tool that available on amazon for about $450 last time I looked at them. It would be better to just borrow one if possible. A scan tool wouldn't do much good if the modules are powered and communicating tho Relearning shouldn't need to be done if its the original modules and sensors. SInce you didn't swap the accelerator pedal it shoiuldnt have to be messed with but If the pedal is at 80% (pedal to the floor) and engine rpm less than 600 it enters a clear flood mode which would prevent the injectors from working. Pretty rare to have happen but you cant rule anything out. Sometimes the engine coolant temp can even cause a engine crank no start symptom. I would make sure your modules are working tho.
Teching In
Joined: Sep 2018
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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.