HELP, trouble starting LS3 416.
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TECH Apprentice
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From: Lawrenceville, GA
HELP, trouble starting LS3 416. Okay I have a LS3 416 conversion in a 2000ss camaro. When it sits for a while it'll fire right up, but if I've been driving it or just letting it run for a bit it'll turn over forever before it'll start up. It also pops through the exhaust when it turns over. Everything is new on this motor & it doesn't even have 100 miles on it. My thought is it might be the cam sensor, but it's new. Any other place I should be looking? Also LME built the motor so I know all the right reluctor wheels are on the motor. Any help would be awesome!
I saw your post on YB but I am unable to join there to respond. Good thing you used the same user ID. 
The cam sensor wires are likely in the wrong position. When extending the wires the two outside wires on the connector need to be swapped. Did you extend the wires yourself or did you purchase an extension harness?
The cam sensor wires are likely in the wrong position. When extending the wires the two outside wires on the connector need to be swapped. Did you extend the wires yourself or did you purchase an extension harness?
From your description of the problem it definitely points to the PCM not receiving the signal from the cam sensor. If you have tried the wires in both positions and it still does it, then I would lean towards the engine having the wrong cam sprocket. Are you plugging the extension harness directly into the sensor itself or do you have the jumper harness that bolts to the front cover?
You should also be getting a DTC for the cam sensor. Have you checked the codes?
You should also be getting a DTC for the cam sensor. Have you checked the codes?
Thread Starter
TECH Apprentice
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From: Lawrenceville, GA
I'm going to go over it a little better this weekend. Do some double checks & scan the car for trouble codes. Checked with Lme and they said they installed the right sproket on the cam. It's one of those pesky problems, but as far as a check engine light for dtc's I don't have anything popping up on the dash. I'll get back on here after the weekend and see what I can come up with.
If it starts and runs perfect when it's cold but not when it's hot, then the problem is in the tune, not the cam sensor. The sensor can't tell the difference in a cold and hot motor, so it should act the same all the time if that were the problem.
On The Tree
Joined: Aug 2010
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From: Melbourne
Man i had the same issue a while ago. Turns out I had a loose pin in the cam sensor after switching wires. Just double check it. Also popping while cranking is indicative of a bad cam sensor. After checking the wiring I'd get a new sensor pronto
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Double check that you have a 1x and not a 4x cam sprocket (assuming you are still using the stock 2000 PCM). Most LS3 based builds use 4x cam gears and 58 tooth crank reluctor wheels.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
TECH Fanatic
Joined: Aug 2005
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From: Sunny London, UK
Does it turn over slower when warm?
Quite a few dudes have found issues with the earlier starters and slow crank when hot.
A late model Camaro 2010 starter fixes things nicely and is pretty cheap.
Quite a few dudes have found issues with the earlier starters and slow crank when hot.
A late model Camaro 2010 starter fixes things nicely and is pretty cheap.
If you dont have cel
Then it is a hot start issue.
I have this same issue in my Gto I've never been able to get it down no matter what adjustment I do In the start up air flow tables.
I don't have a cel for a CPs sensor either
Then it is a hot start issue.
I have this same issue in my Gto I've never been able to get it down no matter what adjustment I do In the start up air flow tables.
I don't have a cel for a CPs sensor either
Teching In
Joined: Apr 2009
Posts: 5
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From: Toluca Lake
Peep the hot start tables in the logs yet? My car has always started with more authority (for lack of better term) when cold versus hot. Before adjusting the hot start values it would act similar to your description.
Personally, I'm going to take a stab in the dark and say your cold vs. hot start issue and the popping during cranking are independant issues. As was mentioned above, the tune is what affects the cold/hot starts, and that popping and hard start is probably like what was diagnosed above with the cam sensor/sprocket.
Personally, I'm going to take a stab in the dark and say your cold vs. hot start issue and the popping during cranking are independant issues. As was mentioned above, the tune is what affects the cold/hot starts, and that popping and hard start is probably like what was diagnosed above with the cam sensor/sprocket.
