knocking?

[o' dannyboy]

I've got a 93' xlt with 162K on it. It's been babied since day one and runs great. It's got plenty of new stuff; Bosch injectors, BBK TB, Gibson exhaust etc. The upper manifold gasket was replaced when the injectors were swapped and everything torqued down properly to spec. The MAF has been cleaned regularly as well. The problem is a knock/rattle on acceleration, usually uphill on the Williamsburg bridge. She accelerates really well up the hill but knocks/rattles a bit between 2k and 3k rpm. The odd thing is, I've noticed that there is no knock/rattle when she's cold, and less when it's cold outside <35 degrees when she's warm. The rattle has been there before and after any mods or repairs. She really runs great, snappy acceleration etc. this knock is all that keeps her from being puuuuuuurrrrrrfect and it's driving me nutz!

Any ideas?

 

[Exploderpilot]

how high pitched is the noise?

 

[o' dannyboy]

knocking...

I've got a 93' xlt with 162K on it. It's been babied since day one and runs great. It's got plenty of new stuff; Bosch injectors, BBK TB, Gibson exhaust etc. The upper manifold gasket was replaced when the injectors were swapped and everything torqued down properly to spec. The MAF has been cleaned regularly as well. The problem is a knock/rattle on acceleration, usually uphill on the Williamsburg bridge. She accelerates really well up the hill but knocks/rattles a bit between 2k and 3k rpm. The odd thing is, I've noticed that there is no knock/rattle when she's cold, and less when it's cold outside <35 degrees when she's warm. The rattle has been there before and after any mods or repairs. She really runs great, snappy acceleration etc. this knock is all that keeps her from being puuuuuuurrrrrrfect and it's driving me nutz!

Any ideas?

It's not hard. It's more like a flutter - I was guessing detonation, a mixture issue or sticky valve or something...

 

[ThePhoenix]

run some engine cleaner through it...

 

[o' dannyboy]

knocking...

run some engine cleaner through it...

... SeaFoam™?

 

[ThePhoenix]

i did the seafoam...gave me a pep-ier engine...and it was fun to smoke out my parking lot

 

[rookieshooter]

Seems the spark is getting there just a tad bit soon mate. This will cause the air gap or put another way, the space that the oil takes up between bearing and the connecting rod rod crank throw. This space relatively speaking is taken up gradually as the crank spins on its axis. At optimum correlation between the angle of the connecting rod and crank throw the spark has ignited the air/fuel mixtures forcing the piston, down on the crank arm. If this spark gets there too soon before the air gap has a chance to decrease as the piston is going up, then Whamo ping or the metallic sound of the piston being forced down on the crank arm too soon. Sometimes higher octane might help. This I have to do on my high compression mill.
Is there a way you can retard your timing?