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

car has a low rpm stumble

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Old 08-08-2008, 01:16 AM
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Default car has a low rpm stumble

i just did long tube and when in gear i wants to die, rough idle, and stumble.i got the air pump unpluged all the line are still in. just waiting to get egr block off plates.air an rear o2 still need to be tuned out. could it be a burned wire or something? as so i just put in a wideband o2 and it always spike to 16 or so the backs down to 14 ish why dose this do that?
Old 08-08-2008, 02:15 AM
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Originally Posted by jamiebob
i just did long tube and when in gear i wants to die, rough idle, and stumble.i got the air pump unpluged all the line are still in. just waiting to get egr block off plates.air an rear o2 still need to be tuned out. could it be a burned wire or something? as so i just put in a wideband o2 and it always spike to 16 or so the backs down to 14 ish why dose this do that?
I will ask, did you replace the plugs/wires while installing the headers? If not, you need to, also, how old are the o2s, if they are old, they may need replaced, mine were fine when i installed my headers, but they weren't that old, i also installed new plugs/wires while doing this, it fired right up & everything worked out great.
Old 08-08-2008, 08:11 AM
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sounds like you are having the same fun ive been having for over a year... see my plug wire thread. good luck man
Old 08-08-2008, 08:56 AM
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I would get a new set of front o2's in that bad boy. When I did the coated headers on my car it smoked the o2's. Car ran like trash. Replaced em' and reset the computer (removed battery) and it ran fine.
Old 08-08-2008, 09:07 AM
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yea you are supposed to heat cycle coated headers before installing the oxygen sensors.
Old 08-08-2008, 09:17 AM
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Yea I actually got a "lightly" used set ( <1k miles), so I figured I was good to go. Apparently not. Whats a 120$ whoopsie when it comes to my toy? :-p
Old 08-08-2008, 09:20 AM
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if you happen to have a scanner or datalogging software you can tell if it is the 02s really easy because the missfiring will only occur in closed loop
Old 08-08-2008, 01:52 PM
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check for vacuum leaks and your plug wires, and also check the wire that goes from the coil to the opti. if its O2s, then the symptoms would go away under WOT because the computer doesnt read them then (i changed mine and it didnt fix it). i had this low rpm stumble for a while, and while pulling out this motor i noticed corossion on the coil where the wire to the opti goes, my vacuum lines were pretty much destroyed, and my plug wires are caked with grime. hoping these were the culprits.

and make sure you go with AC delco O2 sensors.



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