Running really rough and down on power - struggle to rev out
06-07-2020, 07:33 AM
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Running really rough and down on power - struggle to rev out
Have a friend's 350z I'm trying to help fix - the car is running really rough (missing) and really down on power.
You can hear it "missing" on idle, it's kind of inconsistent as sometimes it would start perfectly fine but that is getting rarer. When you accelerate while in neutral it seems to rev out ok and sound normal but when driving and having the motor under any load it will missfire and just run really poorly. It will kind of "jump" through the rpm range, if you went WOT instead of a nice smooth quick response up to redline it will kind of hesitate then jump a few around.
Things I have tried;
Spark plugs are not that old - all look good colour wise.
Tested resistance on coil pack pins - all seemed very close to each other, not sure if this is a way to 100% rule out faulty coil packs though?
Unplugged coil packs while running - instantly begins misfiring heavily.
MAF looks clean.
compression test results were excellent
Not really sure where to go from here, it's not throwing any obd codes being an Aussie model apparently the obd is not 100% implemented like the overseas models.
Kind of leaning towards a intake leak somewhere but have checked all the hoses and have not found anything, unless there are some hidden ones?
Can hear an air suction type noise right near the PCV- is this normal?
Honestly kind of stumped - Thinking it's a bad sensor or vac leak? I know the engine is healthy from a comp test and that would also indicate valve timing is good too, so thinking either coils/sensor/vac leak?
Hopefully someone has seen this before and can help
You can hear it "missing" on idle, it's kind of inconsistent as sometimes it would start perfectly fine but that is getting rarer. When you accelerate while in neutral it seems to rev out ok and sound normal but when driving and having the motor under any load it will missfire and just run really poorly. It will kind of "jump" through the rpm range, if you went WOT instead of a nice smooth quick response up to redline it will kind of hesitate then jump a few around.
Things I have tried;
Spark plugs are not that old - all look good colour wise.
Tested resistance on coil pack pins - all seemed very close to each other, not sure if this is a way to 100% rule out faulty coil packs though?
Unplugged coil packs while running - instantly begins misfiring heavily.
MAF looks clean.
compression test results were excellent
Not really sure where to go from here, it's not throwing any obd codes being an Aussie model apparently the obd is not 100% implemented like the overseas models.
Kind of leaning towards a intake leak somewhere but have checked all the hoses and have not found anything, unless there are some hidden ones?
Can hear an air suction type noise right near the PCV- is this normal?
Honestly kind of stumped - Thinking it's a bad sensor or vac leak? I know the engine is healthy from a comp test and that would also indicate valve timing is good too, so thinking either coils/sensor/vac leak?
Hopefully someone has seen this before and can help
Last edited by Booki89; 06-07-2020 at 06:43 PM.
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