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

LT1 Miss fire

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Old Apr 3, 2008 | 09:11 PM
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Default LT1 Miss fire

1997 b4c miss fires at mid to high rpm only if you gradually go through them. if you mash it it does fine? iam lost had a simular problem a year ago and replaced the opti spark, ignition module, coil, and all the wires and plugs any help out there.

Optispark fixed it last time.
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Old Apr 3, 2008 | 09:35 PM
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is it sputtering as you slowly accelerate holding the pedal in one spot or does it happen as you roll into the gas if its when you roll into it, it may have something to do with your TPS.
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Old Apr 3, 2008 | 09:36 PM
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man that sucks im experiencing the same problem....misfires are the most frustrating code....
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Old Apr 4, 2008 | 01:20 AM
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How do you know it is a missfire, are you getting any codes?
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Old Apr 4, 2008 | 07:23 AM
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yea it has thrown the code several times and it is more so the holding the pedal in one spot but if you roll into to it real slow it starts missing about 3500 on up nut it is real sparatic not like a dead miss or from like a wire or a plug.
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Old Apr 4, 2008 | 07:29 AM
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But it does not miss if you are just riding down the rode staying bellow 3500 it runs like a champ.
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Old Apr 4, 2008 | 10:55 AM
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im experiencing the same thing, but at idle. if its idling it will start to drop a cylinder or 2 and pop thru the exhaust, backfires like hell, but once i get it out on the road it runs like a champ. possibly bad injector due to the pulses is one thing i could reccomend about checking, but mine is batch fire, 93 wiring systems SUCK!
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Old Apr 4, 2008 | 10:59 AM
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Get more info up. Like last time you changed the Fuel filter and When is ever have you changed the o2's.
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Old Apr 4, 2008 | 11:36 AM
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dont know when was the last filter change and i do have a o2 sensor code coming up to but i didnt know if that would be a factor.
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Old Apr 4, 2008 | 01:43 PM
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ok new fuel filter has been installed and helped none at all. any suggestions for the next step.
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Old Apr 4, 2008 | 03:47 PM
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if the o2 code is for a front o2, change it. My car misfired like hell and I changed the front o2's, and it got much better but didnt solve the misfire compleatly. Im thinking maybe im just running incredibly rich, and just went ahead and ordered my pcmforless tune to see if that fixes anything. If not, I guess ill be messing with the opti.
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Old Apr 4, 2008 | 04:37 PM
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the o2 is for sensor 2 bank 2 but it is also throwing an evap code and i just got done puttiing a new ignition coil on i had on the shelf from last time and it changed nothing if i do end goin with a new opti what brand shhould i go with?
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Old Apr 4, 2008 | 05:15 PM
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sounds fuel related... check your fuel pressure while driving
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Old Apr 4, 2008 | 10:16 PM
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Definetly post what you find... Im trying to tackle this same problem...
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Old Apr 5, 2008 | 10:59 AM
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Bank2 sensor 2 is nothing. Its the post cat eff. sensor. Let me think out loud for a sec. Newer opti, coil, filter, Does not do it at WOT just cruising up. Try this. I am going to try to stay away from the expensive *** o2's. Try un hooking your maf and see how it runs. When you unhook the maf it is going to try and stumble. Dont let it die. You will force the PCM in to SD mode. See if that helps. Also I know you said you just replaced them but plz do check the wires again. Make sure one did not get cooked, or start to arc. If you get a chance pull the #5 plug out and see what it looks like. This should be a pretty quick checks. Yes there is a reason I ask for you to look at specifly #5 plug.
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Old Apr 8, 2008 | 01:33 PM
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tryed the maf and did not effect anything but now the car will not throw a missfire code but is still stumbling all over it self. i checked the plug wires and they look fine but i have not had a chance to pull the plug.
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Old Apr 8, 2008 | 02:34 PM
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Ok lastly. Tripple check everything, vaccuum leaks the works. My question is does it stumble right from first start of the morning or does it just do it when it warms up. If it does it right from start up I would look at the opti again. If it only does it when warm I would change the o2's and clear the Fuel trims.
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Old Apr 8, 2008 | 02:36 PM
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Before replacing the opti look at the harness conections and be sure the are not heavily corroded. Any more info you have might help me get a better idea to.
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Old Apr 9, 2008 | 12:52 PM
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it does it all the time cold hot it dont matter and progressively been getting worse.
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Old Apr 9, 2008 | 01:30 PM
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God that sounds like vacuum.
Mike
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