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ls3 418 stroker, won't start

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Old 05-20-2017, 09:15 PM   #1
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Default ls3 418 stroker, won't start

I just got done building and putting a ls3 418 into my 99 TA. It's a brand new 6.2L block with an eagle stroker kit with mahle pistons. It has GMPP cnc ported ls3 821 heads. a ported ls3 intake with 90lb. ls3 style injectors. I changed the injection connection plugs to newer style. Yella terra rockers and hardened push rods. I also used newer coils. A Mark Williams 90mm throttle body. I used all new sensors throughout the motor. I got everything connected and changed over. I removed all the ls1 smog equipment and knock sensors. I also did not connect the rear set of o2 sensors. The computer has not gotten a tune yet. When I try to start it pops and coughs but does not start. I am not sure where to start on how to diagnosis this. I know the lines on the timing chain lined up. The only thing I can think of is the coils are possibly not in order. But I have been told that does not matter. Or that the computer needs a tune with all the changes. Any positive help would be greatly appreciated as I am at a loss as where to start.
Thanks!
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Old 05-20-2017, 11:09 PM   #2
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1. What gear on the crank? 24x or 58x
2. What timing chain set did you use?
3. What color crank sensor gray or black?
4. Did you use the cam and knock sensor extension harness?

Those questions should get any of us on board with helping
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Old 05-20-2017, 11:23 PM   #3
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24x, I believe the crank sensor is black. No cam sensor and knock sensors. I have to look up what timing set I used.
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Old 05-20-2017, 11:29 PM   #4
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There should be a cam sensor on the front cover. And you HAVE to use the cam and knock sensor extension harness and youve got to have knock sensors.
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Old 05-20-2017, 11:35 PM   #5
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my car never had a cam sensor. It's a 99 firebird
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Old 05-20-2017, 11:44 PM   #6
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The Gen III (original engine) cam sensor was on top of the block in the rear, close to the oil pressure sensor. You car was born with one, rest assured.
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Old 05-20-2017, 11:50 PM   #7
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Every sfi engine has to have a cam sensor.
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Old 05-21-2017, 12:20 AM   #8
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These are the things you need to put a gen4 block into a 4th gen fbody
Ls2/3 front cover kit
1x timing set/24x crank/black sensor
4x timig set/58x crank/gray sensor/lingenfelter conversion box
Cam and knock sensor extension harness

You need those things. There is no other way.
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Old 05-21-2017, 01:17 AM   #9
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It will start without a cam sensor with enough cranking.
Im
Guessing it's way too lean
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Old 05-21-2017, 01:21 AM   #10
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It would only run on base time normally then (iirc) and def throw codes, never run right, and always be hard to start.
Not having any cam sensor even plugged in idk but i think thats a bigger issue though.
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Old 05-21-2017, 01:51 AM   #11
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It will throw codes and always be long cranking. But it will start without the cam sensor. I just went through this with a shitty cam sensor extension harness
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Old 05-21-2017, 12:30 PM   #12
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I was under the impression that you do not need knock sensors to run. I have a pretty "lopey" cam and 12:1 compression which will make the knock sensors retard the timing. I have read that they can be tuned out. So I did not put them in. Do I really need them?
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Old 05-21-2017, 06:54 PM   #13
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If they can run on solid roller setups theu can run on a hyd setup too. You need them otherwise you are flying blind. You can soften them in the tune which is easy but theyll still report. They are a def must for a car that ever gets driven on the street or uses pump gas.
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Old 05-31-2017, 05:00 PM   #14
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I have a 24X crank, ls2 timing set and just converted to the front cam sensor. Still the same problem. I am working on installing knock sensors. I also noticed the rpm gauge is not moving. I have the black crankshaft sensor. It's a AC-Delco unit. Can it be the problem?
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Old 05-31-2017, 05:05 PM   #15
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Youll want to check in whichever cam sensor extension harness you have. Sometimes the pins are swapped wrong. A search on here will tell you what needs to be where. Ls2 had 2 separate timing sets, a 1x and a 4x. Your cam gear needs to look like a half moon.
The black crank sensor is right. The crank gear has to look like offset teeth like 2 separate plates welded together.
The computer def needs a tune anyway but those should be checked as well.
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Old 05-31-2017, 09:20 PM   #16
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Sorry, I did not realize their are 2 ls2 timing sets. I have the 1x, half moon/circle. That's crank gear I have. It's an eagle forged stroker crank with 24x. Thanks for the help!

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Old 05-31-2017, 09:49 PM   #17
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Short of checking the pinout for the cam sensor harness it should start. unless the security is the issue. itll def need a tune though. rpm not picking up is odd.
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Old 06-04-2017, 07:53 PM   #18
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With 90lb injectors, and I can't understand why you went that big, you will certainly have to have a tune before it will ever start and run.
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Old 06-04-2017, 08:03 PM   #19
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^ that seems to be yet another issue.
Unless you plan to boost or use dry nitrous there shouldn't be a need for that size inj anyway. On that engine a 50-60lb inj would be well more than enough.
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Old 06-25-2017, 06:48 PM   #20
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I put in the cam sensor. Had to reverse the two outside wires, it had a code for it. I also got a code for the crankshaft position sensor. Put in a new one. no more code. Put in knock sensors and switched out to 60lb injectors. I do plan on running nitrous once the motor is broke in. It still will not start!!! It coughs and pops a little acts like it want to start but nothing! I am not getting any codes other than for the emissions I pulled off. The tach still does not move. I don't know what else to do. I am thinking about sending the pcm to be programmed. Other than that I am going to check the fuel pressure.
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