Looking for advice from someone way smarter than I am on this....
I have a '99 Firebird that I recently did the 3.8 to 5.7 swap on ( '99 chassis, 99 LS1 and 99 ECU). I have roughly 150 miles on the refreshed LS1. Car ran fine when I first finished the build, but after about 140 miles on this rebuild, it started throwing the dreaded P0300. According to my scanner, cylinders #4 and 7 are the main culprits, although #1 started to misfire the last two times I checked it now. I have done the following mods to my engine:
- LT headers
- EGR, rear O2 and AIR deletes and tuned out
- LS6 Intake (Car was throwing P0300 way before I swapped to LS6 intake)
- LS6 PCV/Valley Cover conversion
I have done/tried the following:
- Replaced pretty much every stupid sensor on the engine
- Did a compression test, and all numbers were stable and consistent
- Replaced Valley cover and intake gaskets
- Swapped Injectors around, no change in cylinders
- Swapped coils and coil wiring harnesses around, no change
- swapped my O2 sensors around to see if misfires changed sides (Running Bosch 13111's)
- Replaced plugs (NGK TR55's) and wires
- Tried CASE relearn with VCM Scanner, but almost impossible to tell if it worked with the newest software version
Things I haven't done:
- Blown car up yet
- Lost my S**t
- Fixed it!
I've attached an idle log from earlier today, as well as the current tune. I'm still learning how to read all the sensors, so I'm not quite sure what to look for for faulty readings yet, so any assistance on what looks bad and where to check next is GREATLY appreciated. Thanks for any/all help guys!
Last edited by Thatguy8898; 05-26-2019 at 04:16 PM.
Reply With Quote