Engine rattle?

[newnico]

hello i'm excited to be newdie on this website and hope I can get some help!
I've been having problems with my gas mileage and engine rattle. when at idle the truck does not buck kick or sputter and I can rev it in park and no odd sounds are heard. but when I am driving the engine sounds like a fork is being tossed around in a garbage disposal. I was told this is caused by a pre-ignition in the engine. the codes being thrown when I do a scan signal the mass airflow, and cad. the rattle is ALOT quieter when I run premium through it but really loud when I run regular through it.
thanks for the help , hope a fix wont break the bank!

[Q451990]

to NICO!

I'm not familiar with a code for CAD? Check out your truck's factory service manual at www.nissanservicemanual.com

I would start by checking the timing to be sure it's set properly.

Heath

[newnico]

catalytic converter (cad) and it doesn't shake at all so I don't think timing would be off, I think the rattle is from the pistons firing before they are supposed to and then becoming out of sink

[whomadewho]

What engine ???

[Desert Rat]

Running premium and reducing it points to detonation. This will cause damage to the engine if you push it hard while it's doing this.

Is it running hot? A hot running engine will be more prone to detonation.

Have you had the distributor out at any point? Try backing off the timing a bit by turning the distributor a bit counterclockwise. A timing light comes in handy here because you can see your marks.