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Old January 11th, 2011, 12:17 AM   #1
fordman95
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Default 97 350 vortec problems

we got the spark issue fixed. now we are having a problem with it misfiring while driving down the road. weve changed the distributor, cam sensor and a couple other things that weve tried. i am at a loss with this darn thing. i had it hooked up to my snap on scanner and i cant find anything wrong with it other than the cam retard offset is at 14 degrees and it should be at 0 give or take 2 degrees. is there anything that someone can tell me to try with it short of changing the computer or taking it to the electrical shop. we did change from a 305 to the 350 but used all the same components off of the 305 including the heads. should we have changed the computer to compensate for this? i am not that much of a chevy guy so i dont know a whole lot about that type of thing. it is not throwing any codes on the scanner not even a misfire on any of the cylinders. it acts like it is just losing spark for a split second then comes back into it. and if u stab the throttle it runs good until u let up. any suggestions

Last edited by fordman95; January 24th, 2011 at 11:55 AM.
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Old January 11th, 2011, 12:34 AM   #2
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check the cap and rotor contacts are clean-ish, check the nut on the ground wire stud by the crank pulley is tight, and also check the distributor case for cracks.

my bet is the ground stud is loose. I've had 2 different 96-99's do this same deal to me.
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Old January 11th, 2011, 09:42 AM   #3
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If you have spark out of the coil wire and not out of the spark plug wires, then the problem has to be in the Distributor Cap and/or Rotor.
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Old January 24th, 2011, 11:58 AM   #4
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bump for new problems. read the first post
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Old January 24th, 2011, 12:14 PM   #5
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you have to get the cam retard reading closer to zero, all u have to do is set the scanner to adjust cam retard and adjust the distributor a little at a time, snap throttle over two thousand until it reads close to zero, try that first. other than that make sure no cracked porcelin on plugs.
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Old January 24th, 2011, 12:20 PM   #6
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does it tick at all now? my friend had the same exact problem and replaced all the exact same things u did and it turned out to be a broken valve spring

just my .02
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Old January 24th, 2011, 11:48 PM   #7
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Quote:
Originally Posted by davidkassie View Post
you have to get the cam retard reading closer to zero, all u have to do is set the scanner to adjust cam retard and adjust the distributor a little at a time, snap throttle over two thousand until it reads close to zero, try that first. other than that make sure no cracked porcelin on plugs.
ok i will try that next. i did not know that u had to snap the throttle like that. thanks for the input
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Old January 24th, 2011, 11:50 PM   #8
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Quote:
Originally Posted by muddinman56 View Post
does it tick at all now? my friend had the same exact problem and replaced all the exact same things u did and it turned out to be a broken valve spring

just my .02
nope there are no noises whatsoever in the motor. i have had the motor runnin with the valve covers off and there is nothing at all. dont smoke tick knock nothin. but thanks for the input. ill take any info i can get
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Old January 25th, 2011, 12:39 AM   #9
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possibly a fuel table issue (get the correct ecm, reflash what you have, or get a custom tune which acomodates your smaller chamber volumes). these ecm's only have a 15% learn curve iirc. not sure if the spider injectors are the same between both intakes, but which did you use?

305 to 350 is a big change for the better :)
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Old January 25th, 2011, 09:05 AM   #10
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I'd check the spider injectors, the lines running to them are plastic and constantly in oil, they get brittle and crack over time.
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