LT1-LT4 Modifications 1993-97 Gen II Small Block V8

lt1 355 first start up help..

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Old Apr 26, 2012 | 04:17 PM
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Default lt1 355 first start up help..

Hey there lt1 people I ran into a problem. I tried to start up the engine for the first time its a 355 about 11.8 compression ratio and a 232/240 cam as I'm cranking the engine on it wouldnt turn on and stay on unless I play with the throttle to keep the engine running , it also smells like carbon oxide by the engine compartment. The spark plugs are also smocked with carbon even after a few minutes it was on. The car is a 93 which its untuned , my question is does the tune really affect it that much to not even allow the car to stay on?? if you guys could help me out i really need help thanks
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Old Apr 26, 2012 | 04:32 PM
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Most definitely. PCMForless is your friend. Good people over there!
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Old Apr 26, 2012 | 04:36 PM
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I have read great things about pcmforless and people with great results. I never would of though the engine wouldn't even turn on for not having it tuned!..
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Old Apr 26, 2012 | 04:40 PM
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it should still crank and turn on and run rough i'm going through almost the same thing right now except car only starts at wide open throttle, it should start and run rough atleast...
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Old Apr 26, 2012 | 04:43 PM
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Originally Posted by 96z28_lt1
it should still crank and turn on and run rough i'm going through almost the same thing right now except car only starts at wide open throttle, it should start and run rough atleast...
x2x...

i just got my 357 up and running....still working out leaks at the moment.

regardless of what you did mods wise it should still crank up and fire on its own....

give us a rough breakdown of whats done to it.
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Old Apr 26, 2012 | 04:48 PM
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355 .30 bored 11.8 compression 232/240 565/568 110 lsa cam ported heads 3 angle cuts ported intake manifold 36 lb injectors (but swich back to the stock ones thinking it was the problem) long tubes headers .. The fuel pressure its at 45 psi no vacumm leaks.. the car will turn on if i play with the throttle and will stay on but if i left off it turns off..
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Old Apr 26, 2012 | 04:52 PM
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lol with that size of a cam and that LSA you for sure need a tune. It will never Idle and you most likely wont be able to keep it running long with the throttle.
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Old Apr 26, 2012 | 04:54 PM
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about the Injectors should it tune it with the 36 lb.. or goo with something smaller
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Old Apr 26, 2012 | 05:39 PM
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It was to be tuned especially with the mods you have its a MUST.
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Old Apr 26, 2012 | 05:45 PM
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Put your stock injectors back on it
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Old Apr 26, 2012 | 06:17 PM
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Change injectors back and have it tuned for the bigger ones. Right now the computer is spraying fuel for a smaller injector which means it is DUMPING fuel for the bigger ones.
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Old Apr 26, 2012 | 06:21 PM
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Wouldnt it atleast stay on even if its not tuned??
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Old Apr 26, 2012 | 06:41 PM
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You have changed EVERYTHING about the engine - the PCM has limited flexibility for minor changes but with mods to that extent it simply can't correct. If you want to have a prayer of it running correctly (and more importantly prevent any physical mechanical damage) you'll get a tune.
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Old Apr 26, 2012 | 07:11 PM
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You are LUCKY it died because since your stock injectors were 22lbs and you put 36lbs on it is spraying nearly 65% more fuel which is enough to ruin the engine FAST.

Then far as further tuning the stock cam can idle at 600rpm I think even lower under some conditions, that cam is probably going to want at least 900rpm cold in park/neutral.
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Old Apr 26, 2012 | 07:12 PM
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Listen to everything Ramair said... YOU NEED A TUNE.
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Old Apr 26, 2012 | 07:19 PM
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ZOMG! You put 36# injectors in, you started it and you didn't even get a tune?!?

You could have sent your pcm out while you were building it!
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Old Apr 26, 2012 | 07:19 PM
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Then tune it is. I knew I needed a tune but I just thought it would be nice to hear how she sounded. After all its my first build if you would call it that, I got too carried away but like RAMAIR I'll wait Until I get a tune from pcmforless and hopefully it fixes the problem thanks eveyone..
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Old Apr 26, 2012 | 07:23 PM
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With the PCM fuse pulled I would pull all the plugs and crank it over to blow the fuel out. That way there is no injector pulse of spark.

Change the oil before you start it again too.

Seriously that is enough fuel to wash all the oil off the cylinder walls and maybe even enough to cause rich detonation. Hopefully it is OK.
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Old Apr 26, 2012 | 07:24 PM
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Originally Posted by Fastredz28
Then tune it is. I knew I needed a tune but I just thought it would be nice to hear how she sounded. After all its my first build if you would call it that, I got too carried away but like RAMAIR I'll wait Until I get a tune from pcmforless and hopefully it fixes the problem thanks eveyone..
Don't forget to buy new spark plugs before you start it up again. Better yet, have someone hide your keys till you get your pcm reprogrammed

Lesson learned and best of luck!
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Old Apr 26, 2012 | 08:48 PM
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Originally Posted by Rob94hawk
Don't forget to buy new spark plugs before you start it up again. Better yet, have someone hide your keys till you get your pcm reprogrammed
Lesson learned and best of luck!
Constructive criticism...gotta love it.
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