Spark Knock
#21
Dr. Wired
iTrader: (2)
I strongly doubt damage has been done.
If you check the owner's manual it states that light spark knock under heavy load is expected.
Sometimes it's audible, sometimes it's not.
There are several causes of knock:
too lean -- doesn't typically happen on VQ35de and if it does, you typically get a CEL
too much timing advance -- probably the culprit, factory timing is fairly aggressive, and this varies from car to car as nissan has used MANY revisions of the ECU.
cylinder temps too high -- doubtful, and not much you can do about it.
oil vapors getting burned -- you might consider getting an oil change and using slightly heavier oil. if you're using 5W-30 try 10W-30. This could also happen depending on your PCV function. You also might look into installing an oil catch can, I've heard from some people on this forum that this can help knock.
You're already using 93 octane which is higher than the recommended minimum octane (91). Octane shouldn't be your problem, because you should not be putting octane booster in your car at every fill up. That is just retarded, and most octane boosters only raise your octane like 0.2 or something.
OR... you can just not worry about it. I've had aggressive spark knock on the dyno several times under heavy load and it did not cause damage at all. Like I said, factory timing is fairly aggressively advanced, so it's not too uncommon to see stock cars knocking. And since the stock ECU has a very reliable knock sensor, I would not really worry about it (but everytime I say this, someone jumps in and disagrees with me)
If you check the owner's manual it states that light spark knock under heavy load is expected.
Sometimes it's audible, sometimes it's not.
There are several causes of knock:
too lean -- doesn't typically happen on VQ35de and if it does, you typically get a CEL
too much timing advance -- probably the culprit, factory timing is fairly aggressive, and this varies from car to car as nissan has used MANY revisions of the ECU.
cylinder temps too high -- doubtful, and not much you can do about it.
oil vapors getting burned -- you might consider getting an oil change and using slightly heavier oil. if you're using 5W-30 try 10W-30. This could also happen depending on your PCV function. You also might look into installing an oil catch can, I've heard from some people on this forum that this can help knock.
You're already using 93 octane which is higher than the recommended minimum octane (91). Octane shouldn't be your problem, because you should not be putting octane booster in your car at every fill up. That is just retarded, and most octane boosters only raise your octane like 0.2 or something.
OR... you can just not worry about it. I've had aggressive spark knock on the dyno several times under heavy load and it did not cause damage at all. Like I said, factory timing is fairly aggressively advanced, so it's not too uncommon to see stock cars knocking. And since the stock ECU has a very reliable knock sensor, I would not really worry about it (but everytime I say this, someone jumps in and disagrees with me)
Last edited by Wired 24/7; 06-25-2007 at 10:25 AM.
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