Yes a tune will fix that... DO NOT CONTINUE TO DO IT.. pull a few plugs out to look at them, post your findings as to the color of them..

 

I would be willing to bet its either the "sewing machine" noise (if it were cammed or just has longer push rods as if it were cammed at one point and the rods werent replaced) or just normal ticking.. my 4.8 had a little bit of a tick from the time I bought it.

I also think you're reading way too much into the fuel choice. If its 91 its 91 everywhere it doesnt matter how "premium" they state it is. Some places even say the "fuel can be oxygenated between X month and X month".

 

ok. maybe im wrong but if your lifters are knocking....you need to get it fixed. one day i left poplar bluff when i had my 5.3 and my truck was running the best it ever did. by the time i got to ellsinore where i live ( 30 miles max), my lifters were knocking like crazy. parked it. put in a new oil pump. drove it one day then had a motor locked up so tight i had to have a six ft cheater pipe to turn it. id get it fixed if i was you. i dont think that the fuel octane level has a thing to do with it at all. maybe yhou just happen to hear it when you run it. and a tune is not going to make a difference either i wouldnt think. do you have good oil pressure?

 

Need to hear the noise...if it's only making the noise under load, and 93 octane gas helps it, it's probably preignition/detonation. If you have access to a scan tool, you can monitor KR (knock retard), and see if you're getting any when the noise occurs. I'd also look at the data and see how much timing you're running, you may have to take it back a few degrees. It wouldn't hurt to perform an induction service with a product like "Seafoam" (if you search Seafoam you'll find a bunch of threads about it).

Will it make the noise if you're in park or neutral and you bring the RPM's up?

 

Gasoline octane varies around here all of the time. If I wait a couple of miles after I fill up and then open the throttle big at low rpm, the engine will rattle if they slipped me the wrong gas. I check every fill-up, to make sure before I beat on it. Maybe it's just a local thing, and you are luckey in your part of AZ. Or maybe it is how close to the edge your tune is.

 

i have the same problem.

 

if higher octane fixes it its def detonation, ever notice how some gas stations are cheaper than others?? its not only location that affects it but the quality stay away from exon and citgo gas although its the cheapest it has the worst quality, chevron and shell is what i stick to u get wut u pay for

 

if its the sewing machine sounds.. it could be ur valve lifters.. also.. you could have a valve float around there... if ur lifters are making all the noise i would change them as soon as possible those DOD lifters suck . .. espeacilly if the truck was cammed and taken above 6000 rpms.. my DOD lifters took a dump at high rpm.. and took my engine with it.. .. I would take a look at the engine and replace the lifters

 

Thanks for the good info everybody. It doesnt do it in neutral or park when it is revved up. Only when I am on the throttle pretty hard and it is under load. If and when I pull my jeep and trailer, it will do it at a lower rpm when on the throttle but mostly from about 4000 rpm and up. I was thinking that I need to back off the timing just a touch but , unlike old school ignition systems, i cant just turn the distributor. Does that have to be done with with the tune or can I do it? Just to add, it does it with 93 octane as well but just barely. When I run the cheap pump gas, it is much worse. And I pulled all the plugs and they didnt look odd and all were consistent with each other. Would predetonation change thier appearance? If so, what would they look like.

 

I vote pinging,too. My stock pig does it sometimes under hard acceleration. I never heard it ping until about a year ago. I give it Sea Foam occasionally.