Just bought an Lt1 she run rough
Thread Starter
Teching In
Joined: Nov 2025
Posts: 2
Likes: 0
Just bought an Lt1 she run rough so I just purchased an 1997 ss camaro with the lt1 for a good price but the issue they we’re having is high idle rpm and over heating turns out they deleted the cats put longtube headers and deleted the o2s. I guess my question is should I replace the cats and 02s or can I just tune the pcm how the car sits with them all removed
O2's are an important sensor for a close to factory vehicle, if there are O2 bungs in the headers and the connectors are still there then I would put them back in and I would bet the car will run much better. car will need a tune if you keep the cats deleted since there is a down stream o2 behind where the cats would be and that will throw it off as well. high idle could also be a vaccum leak somewhere, possibly related to the header install, if there aren't any o2 then who knows what other corners they cut.
Thread Starter
Teching In
Joined: Nov 2025
Posts: 2
Likes: 0
Well he deleted the EVAP an ac also I found a vacuum line running from the bottom of the front of the engine going to the driver side intake that was burnt from the headers and repaired that but still having the issues but now it looks like the alternator is bad the volts stay at 9 in the red
Ran the obd2 codes are P0100 p0101 p0336 p0400 p0403 p0443 p0141 p0161
Ran the obd2 codes are P0100 p0101 p0336 p0400 p0403 p0443 p0141 p0161
Define your definition of overheating what is actually happening. These cars do not turn fans on till almost 235 if it's idling and the ac is off.
As long has it has front left and right 02s installed and active it can control fueling properly. If it doesn't have cats the rears aren't needed their only purpose is cat monitoring.
For diagnostic sake plug evap purge solenoid at the intake.
With front 02s operational and confirmed no vacuum leaks then you can start real diagnostics without throwing a bunch of un needed parts at it. Verify fuel pressures right, fuel filters clean, injectors not leaking and flowing properly and that the ignition side is in order.
If its got all of those codes in it chances are the pcm is stock or has a crappy canned tune in it that doesn't compensate for headers. Next step is flash back to oe tune and then take it somewhere and get it tuned for the headers and the weight reduction program its undergone and it should be running pretty good at this point.
As long has it has front left and right 02s installed and active it can control fueling properly. If it doesn't have cats the rears aren't needed their only purpose is cat monitoring.
For diagnostic sake plug evap purge solenoid at the intake.
With front 02s operational and confirmed no vacuum leaks then you can start real diagnostics without throwing a bunch of un needed parts at it. Verify fuel pressures right, fuel filters clean, injectors not leaking and flowing properly and that the ignition side is in order.
If its got all of those codes in it chances are the pcm is stock or has a crappy canned tune in it that doesn't compensate for headers. Next step is flash back to oe tune and then take it somewhere and get it tuned for the headers and the weight reduction program its undergone and it should be running pretty good at this point.
Teching In
Joined: Sep 2016
Posts: 34
Likes: 12
From: Camp lejeune NC
Well he deleted the EVAP an ac also I found a vacuum line running from the bottom of the front of the engine going to the driver side intake that was burnt from the headers and repaired that but still having the issues but now it looks like the alternator is bad the volts stay at 9 in the red
Ran the obd2 codes are P0100 p0101 p0336 p0400 p0403 p0443 p0141 p0161
Ran the obd2 codes are P0100 p0101 p0336 p0400 p0403 p0443 p0141 p0161