LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

misfire codes are changing on me.?!

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Old 03-23-2013, 08:09 PM
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misfire codes are changing on me.?!

i have a '97. at first i had a P1441 (system flow during non-purge) and a P300 code code (i just bought the car)
replaced some hosing on the top for the purge system because ive read that this code can also cause a misfire. drove the car and got a p302 code the p1441 went away. drove a little more and a p300 came up. drove another mile or two and p302 came back.... now its alternating as i drive every few miles from p302 to p300. the p1441 has not come back. any ideas on what might be going on?
also i have replaced the 1,3,5,7 spark plugs but have not got to the other side yet. any suggestions on how to get to those? its a very cramped space..
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Old 03-23-2013, 09:37 PM
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Re: misfire codes are changing on me.?!

P0302 is telling you #2. That would be a good place to go next. Taking the alternator off may give you some room.
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Old 03-23-2013, 10:18 PM
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not sure about stock manifolds but with my headers I bought the husky pass through socket set at home depot for like 40 bucks and its awesome for changeing spark plugs that would normally be a pita. Some are best to get from under the car and some from above.


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Old 03-24-2013, 10:38 AM
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Re: misfire codes are changing on me.?!

Also check for arcing plug wires when its dark.
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Old 03-24-2013, 09:59 PM
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Re: misfire codes are changing on me.?!

im thinking of switching the ignition cord for the #2 with the #1 on the other side (because i think that might be the only place it can reach, maybe with the #4 but not sure havnt looked yet) and seeing if the misfire moves to that cylinder.. oh boy im excited to get down to the famed optispark..
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Old 03-29-2013, 05:07 PM
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Re: misfire codes are changing on me.?!

Originally Posted by shoebox
P0302 is telling you #2. That would be a good place to go next. Taking the alternator off may give you some room.
So far I have replaced all plugs and also replaced the #2 plug wire. (bought a set but had time enough to change the one) the problem still persists no change. Pulled the plug wire and it really does't seem to run any different. Tested the injector and it's firing also. Still get a P302 and sometimes P300. Is 300 relevent to all cylinders or is is saying the #2 has a random misfire? No other cylinder throws a code only #2. Opti next??
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Old 03-29-2013, 06:30 PM
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Re: misfire codes are changing on me.?!

The P0302 is specific to #2 cylinder. The P0300 means a random misfire. Can be hard to find. Could be any cylinder(s). Have you raised the hood and looked at the plugs/wires when it's really dark to see if there is any arcing?
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Old 03-29-2013, 09:03 PM
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Re: misfire codes are changing on me.?!

yessir theres no such arcing. i have a cheap set of wires i bought because they didnt have the one i needed so i miight change all of them but since i replaced the wire and plug for the #2 and its still misfiring i feel that the problem may lie in the opti. i checked the fuel injector also. its working just fine. any more suggestions before i toss money at an opti?.
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Old 03-30-2013, 12:13 AM
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Re: misfire codes are changing on me.?!

Have you actually checked spark at the end of the wire? Maybe compared it to another?
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Old 03-30-2013, 02:21 AM
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Re: misfire codes are changing on me.?!

Nossir I'll check that first thing tomorrow. And as far as the random I guess ill check them all for spark
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Old 03-30-2013, 12:39 PM
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Re: misfire codes are changing on me.?!

Originally Posted by shoebox
Have you actually checked spark at the end of the wire? Maybe compared it to another?
alright so we've determined that the spark on #2 is in fact weaker, at least at times, than the others. Opti is my next move, and suggestions on what type? i see theres many out there such as RPT, Cardone, Accel and Duralast.
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Old 03-30-2013, 01:24 PM
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Re: misfire codes are changing on me.?!

You probably just need a cap and rotor, but your call depending on mileage. AC-Delco/Delphi is what I would go with and not any of those you listed. If just cap and rotor, MSD would be ok. MHO.
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Old 04-02-2013, 08:21 AM
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Re: misfire codes are changing on me.?!

Originally Posted by shoebox
You probably just need a cap and rotor, but your call depending on mileage. AC-Delco/Delphi is what I would go with and not any of those you listed. If just cap and rotor, MSD would be ok. MHO.
The #2 spark does look a little weaker and it seems like it is not as consistent as the others we checksd. We in fact were discussing what you reccommend in that if all other cylinders are firing with no codes then the cam semsor is working so there should be no reason to replace the unit. Problem could just be in the cap (if rotor you'd think there would be other misfires) I have seen where folks clean everything up (disc and inside) and replace the cap and rotor as part of a normal tune up. Cap and rotor aren't cheap (250.00 for Delco) but that's opposed to 400 something for the unit. We checked with a noid light and inj is firing last thing to check is the inj itself. Swap and make sure the problem stays with the 2 cyl. If so I think we will change cap and rotor. Thanks for the help. At least I know I'm not wrong in thinking that. Someone else has the same view. I'll let you know.
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Old 04-02-2013, 01:30 PM
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Re: misfire codes are changing on me.?!

May not hurt to check your opti vent system for proper operation as well. If the system gets plugged, it can pull the cover to the rotor and cause some of the energy to arc to ground(energy jumps from the trace to the rotor cap screw).

Check the video in the opti sticky(near the end of the thread), at the top of the LT1 forum, on how to check the vent system.
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Old 04-02-2013, 06:55 PM
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Re: misfire codes are changing on me.?!

Originally Posted by ACE1252
May not hurt to check your opti vent system for proper operation as well. If the system gets plugged, it can pull the cover to the rotor and cause some of the energy to arc to ground(energy jumps from the trace to the rotor cap screw).

Check the video in the opti sticky(near the end of the thread), at the top of the LT1 forum, on how to check the vent system.
im sorry i cant seem to find this. you say at the LT1 forum page and then its near the end of the thread? i dont see where.
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