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Trying to help my friend since he's upset about the whole thing and on the verge of giving up
My friends and I recently completed an engine swap on a 2003 350z Enthusiast 6-speed. The motor was a JDM import and matches the trim of the current car. We did take off the harnesses and all the accessories (power steering, pump, alternator, starter, etc.) and used the old motor and chassis components, so those could be considered non-issues. We are leaning towards air, fuel, and spark, so I only mentioned the recent engine swap to consider electronics as well. Side note: friend is trying to keep it cheap since he is currently attending school without a job, hence the following.
1.) Explanation of problem/videos
-- When idling or being driven under 5500 RPM, the car is nearly perfect. A small, intermittent misfire sound can be heard when the hood is popped, but nothing major IMO. Under load, the car sounds like it is hitting the rev limiter at 5500-6000 RPM. This happens under load in any gear and does not change if slowly or suddenly accelerated to that point. See this video to hear the sound it makes when it accelerates to that point.
--In neutral, the car does rev higher and almost to redline, but is subject to a crackling/breaking up sound/kinda sounds like a burble tune. See this video for neutral rev to about 6500 or so.
2.) Known issues/attempted resolutions
-The following have NOT been changed: injectors and coil packs that came with the JDM motor were not changed and are currently being used. Fuel pump and wiring from chassis are the same.
-The car was sitting outside for about a 1.5 years with maybe 3-5 gallons in it. Friend added about maybe about 3 gallons of newer gas to this, so about a 50/50 mix of new and old gas.
-The only code the car throws is: P0300 "Random misfire or multiple cylinder misfires."
-The spark plugs were changed. This did not resolve the issue or code. The previous spark plugs were burnt up such that the gap in the electrode was a lot bigger. Cant remember how they looked in terms of fouling.
--My questions
-Has anyone else had this problem? I know, it seems obvious to just throw money at it to resolve it, but friend is pushing back and is trying to do it cheaply. I'd imagine the best things to do would to be adding more gas, testing the coil packs and injectors, and making sure there are no vacuum leaks, but is there a good order to this? Should we just hand it off to a shop to let them diagnose, might be better than having us try to test everything and throwing money at it?
My friends and I recently completed an engine swap on a 2003 350z Enthusiast 6-speed. The motor was a JDM import and matches the trim of the current car. We did take off the harnesses and all the accessories (power steering, pump, alternator, starter, etc.) and used the old motor and chassis components, so those could be considered non-issues. We are leaning towards air, fuel, and spark, so I only mentioned the recent engine swap to consider electronics as well. Side note: friend is trying to keep it cheap since he is currently attending school without a job, hence the following.
1.) Explanation of problem/videos
-- When idling or being driven under 5500 RPM, the car is nearly perfect. A small, intermittent misfire sound can be heard when the hood is popped, but nothing major IMO. Under load, the car sounds like it is hitting the rev limiter at 5500-6000 RPM. This happens under load in any gear and does not change if slowly or suddenly accelerated to that point. See this video to hear the sound it makes when it accelerates to that point.
--In neutral, the car does rev higher and almost to redline, but is subject to a crackling/breaking up sound/kinda sounds like a burble tune. See this video for neutral rev to about 6500 or so.
2.) Known issues/attempted resolutions
-The following have NOT been changed: injectors and coil packs that came with the JDM motor were not changed and are currently being used. Fuel pump and wiring from chassis are the same.
-The car was sitting outside for about a 1.5 years with maybe 3-5 gallons in it. Friend added about maybe about 3 gallons of newer gas to this, so about a 50/50 mix of new and old gas.
-The only code the car throws is: P0300 "Random misfire or multiple cylinder misfires."
-The spark plugs were changed. This did not resolve the issue or code. The previous spark plugs were burnt up such that the gap in the electrode was a lot bigger. Cant remember how they looked in terms of fouling.
--My questions
-Has anyone else had this problem? I know, it seems obvious to just throw money at it to resolve it, but friend is pushing back and is trying to do it cheaply. I'd imagine the best things to do would to be adding more gas, testing the coil packs and injectors, and making sure there are no vacuum leaks, but is there a good order to this? Should we just hand it off to a shop to let them diagnose, might be better than having us try to test everything and throwing money at it?
