Reads knock when revving on neutral or park???

[BetMinesFaster]

Just curious what to make of it?? reads anywhere from orange to red on the caspers gauge, just wondering where to go or what to look for? I have been chasing a knock problem with it for months already with no luck, its different every time, sometimes 13 or 14 ke, sometimes as little at .7?? No pattern except seems worse in 1-2 than the high gears, and seems to be less kr if you roll into it rather than stabbing it......any thoughts would be great, im not spraying the alky right now because im trying to get the tune dwon correct then add and tune the alky, 92 octane and 16ish on the boost, car has a large fmic and a tt chip with motron 60's, I have tried adding and subtracting fuel with little change, millivolts around 800 at wot and seems to knock very seldom when its not wot, also tried removing some low gear timing with little change as well, curious how one determines what is real and false knock?? Thanks for the help!! Ryan

 

[turbows6]

The exhaust isn't hitting anywhere is it? that will set the knock gauge off.

 

[BetMinesFaster]

It was initially touching the shield under the heater box, I removed it and that did hepl, but did not erase the problem, I know the ds motor mount is not healthy but it does have a strap holding the engine down on that side.....

 

[chrisgarrett]

You cannot have real knock in park or nuetral. Your knock sensor is picking up some noise. An engine with a bad motor mount and a strap can register false knock. In my opinion, you shouldn't even have a strap. Get two good motor mounts and toss the strap.
Real knock will increase in severity. Just to confirm that it is false, you could try throwing in some race gas and see if it still knocks.

 

[slimtastic]

all i know is that i broke my motor cause of the same logic. i would rev my motor up in neutral and it would set off. i thought it was just valvetrain noise,cause i had a full roller cam. turns out i had a gummed up injector not firing properly and it melted the side of my piston while washing out the cylinder in the process... pull all your spark plugs and look for any black dots, roll each cylinder to TDC and check the piston crowns if you can with a flashlight. if you see any piston crowns that are way more clean than the other five by compairison, then check you injectors.

 

[2QUIK6]

You cannot have real knock in park or nuetral.

Sure you can and usually will if revving it up any like the post above...#1 you shouldn't be revving it very high in park or nuetral, and normally you would not see any knock, but it is possible.
If revving it very fast you will get knock because this is horrible on your motor to rev it with no load....kind of like when the tires break loose you can and usually do see some knock when the motor gets unloaded.

Put in some race gas to ensure its false..if you are still seeing the same amount of knock, then assume its false and try to locate the source, and hope its not a knocking rod or bearing.

For the failed injector mentioned above...use a scan tool to see what the BLMs are doing at idle and cruise, if they are not way out of whack then its not an injector.

 

[BetMinesFaster]

Sure you can and usually will if revving it up any like the post above...#1 you shouldn't be revving it very high in park or nuetral, and normally you would not see any knock, but it is possible.
If revving it very fast you will get knock because this is horrible on your motor to rev it with no load....kind of like when the tires break loose you can and usually do see some knock when the motor gets unloaded.

Put in some race gas to ensure its false..if you are still seeing the same amount of knock, then assume its false and try to locate the source, and hope its not a knocking rod or bearing.

For the failed injector mentioned above...use a scan tool to see what the BLMs are doing at idle and cruise, if they are not way out of whack then its not an injector.

I never rev it above 3500 or so in park, i was just doing it to decide if its real or false knock, I just ordered some new poly engine mounts so im going to install them and remove the strap, check once more for any exhaust contack and ill go from there..the injectors have less than 1500 miles on them so im assuming they are fine..it seems to run well otherwise..blm's at cruise are around 125-128..just want to get it running well before I do my winter projects so I know it was right at tear down....dont want to be chasing this gremlin on a new engine in april or may...thanks for the help....

 

[chrisgarrett]

Sure you can and usually will if revving it up any like the post above...#1 you shouldn't be revving it very high in park or nuetral, and normally you would not see any knock, but it is possible.
If revving it very fast you will get knock because this is horrible on your motor to rev it with no load....kind of like when the tires break loose you can and usually do see some knock when the motor gets unloaded.

Put in some race gas to ensure its false..if you are still seeing the same amount of knock, then assume its false and try to locate the source, and hope its not a knocking rod or bearing.

For the failed injector mentioned above...use a scan tool to see what the BLMs are doing at idle and cruise, if they are not way out of whack then its not an injector.

I still say you cannot have real detonation if the engine is not under load. False detonation (noise), yes.

 

[cuda6pak]

Disconnect your knock gauge from the yellow/black wire going to the ecm. I was having similar problems and ended up my gauge was the problem, unplugged it and no more false knock.

 

[tom j]

Mine does the same thing while in park if i rev it, but not while I am driving under normal conditions or racing it unless I playing with the tune or the temp. drops.

 

[2QUIK6]

I still say you cannot have real detonation if the engine is not under load. False detonation (noise), yes.

Maybe not pre-ignition detonation, but real knock from the bearings getting hammered around because of no load, yes..which is what the knock sensor is detecting anyway when there is detonation. Both are equally as damaging and should be avoided.