motor wont start...
Thread Starter
Teching In
Joined: Jul 2010
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motor wont start... I just did an lq4 swap on my 2000 trans am and I used the ls1 harness and ecm. Everything went together great but when I went to start up the car it just cranks and cranks but it won't start up. I checked to see if there was any spark from the plugs and there was NO SPARK. Then I checked the coil pacs and they are getting voltage. So I got new coil pacs and the same think happend. Also the plugs and wires are good. Any help would be greatly appritiated. Thanks
OP: How did you check voltage at the coils? They do get battery voltage on their "D" terminal. The trigger from the PCM comes into the coil on the "C" terminal.
Check the crankshaft sensor and the camshaft sensor. If either of these is unplugged, there will be no trigger to the coils from the PCM.
Can you return those coils? It's not a good idea to just start buying expensive parts before knowing what the cause of the problem is. These coils rarely go bad, they can last over two hundred thousand miles without any failures.
The first thing to check is spark. As he has and there's no spark, it's a good indication that is the cause of the no start. Why would he check something else when he's allready found something not working?
OP: How did you check voltage at the coils? They do get battery voltage on their "D" terminal. The trigger from the PCM comes into the coil on the "C" terminal.
Check the crankshaft sensor and the camshaft sensor. If either of these is unplugged, there will be no trigger to the coils from the PCM.
OP: How did you check voltage at the coils? They do get battery voltage on their "D" terminal. The trigger from the PCM comes into the coil on the "C" terminal.
Check the crankshaft sensor and the camshaft sensor. If either of these is unplugged, there will be no trigger to the coils from the PCM.
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This is odd. Even under the most adverse conditions, with signal from the crank & cam sensors, there should be spark trigger pulses to the coils from the PCM during cranking. All other sensors are of little importance during cranking.
I assume you have good enough battery voltage to crank at a decient speed?
All your harness to engine grounds are good?
The eight coils connect to the PCM via the red mass pin plug. Perhaps this plug is not fully seated into the PCM?
Having failed this, you may need to get a tech scan tool that'll show you sensor response in real time. With this, you'll be able to see crank & cam sensor action while cranking.
What vehicle did this engine come out of?
I assume you have good enough battery voltage to crank at a decient speed?
All your harness to engine grounds are good?
The eight coils connect to the PCM via the red mass pin plug. Perhaps this plug is not fully seated into the PCM?
Having failed this, you may need to get a tech scan tool that'll show you sensor response in real time. With this, you'll be able to see crank & cam sensor action while cranking.
What vehicle did this engine come out of?
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Thread Starter
Teching In
Joined: Jul 2010
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All the grounds from harness to motor are connected. Also I checked all fuses. The motor came out of a 05 silverado and I heard it run. All I used was the block and internals. I used the ls1 accesories and sensors. And also the ecm and harness are from the ls1. I really appritiate the help I need to get my car running conisdering its my only car.
The power to the ignition coils (and fuel injectors) comes from switched power via the key when in "run" and "start" positions. It does go through the "IGN" relay in the underhood fuse block
You've allready confirmed the power to the coils was good. This would indicate the IGN relay and the fuses are good.
Having failed all the common sense things to check and test by eye, hand and test lamp, this might help but you'll need the scan tool:
http://www.hotrodlane.cc/New%20LS%20...0Not%20Run.htm
You've allready confirmed the power to the coils was good. This would indicate the IGN relay and the fuses are good.
Having failed all the common sense things to check and test by eye, hand and test lamp, this might help but you'll need the scan tool:
http://www.hotrodlane.cc/New%20LS%20...0Not%20Run.htm
Have you checked for a good ground at pin A of the coil connectors. Or at least pin-A of coil #3, its a straight shot to ground.
Put a ohm meter or continuity tester between Pin-A and a good ground. Should have a good ground there.
Edit sorry I know you said you checked them but was that a visual or internal check? Do this and it will iliminate a bit.
Put a ohm meter or continuity tester between Pin-A and a good ground. Should have a good ground there.
Edit sorry I know you said you checked them but was that a visual or internal check? Do this and it will iliminate a bit.
You said you were getting power to the coil packs but NOT the plugs. The more I read this it seems to me that its a wire issue. I would try a new set of wires ( hell if it don't work you can take them back) and maybe even new plugs wouldn't hurt. If your using the same wires and plugs from your LS1 the gap might be different for this motor, so that may be an issue. ALL these ideas are good but lets try this one too. Like I said if it don't work you can always take the parts back. I would definitely check on the gap though. Just my thoughts on the situation.....
You said you were getting power to the coil packs but NOT the plugs. The more I read this it seems to me that its a wire issue. I would try a new set of wires ( hell if it don't work you can take them back) and maybe even new plugs wouldn't hurt. If your using the same wires and plugs from your LS1 the gap might be different for this motor, so that may be an issue. ALL these ideas are good but lets try this one too. Like I said if it don't work you can always take the parts back. I would definitely check on the gap though. Just my thoughts on the situation.....