Well there is a big difference in the bed or towing. On the suspension and tires. Tongue weight and haul weight are very different. Probably has nothing to do with your issue jut there is a big difference. I don't run 87 in mine cause its not the preferred octane for performance and detonation. Its possable it could have a valve issue if it was spark knocking. But I'd guess either a coil pack going bad or trash in the fuel and all that weight lowering the rear and trash picked up. Just a wag. Ohh its not the pcm learning a new load. They don't build them to run poor because of slight pcm adjustments.

 

put 1500 pounds in the bed of your truck and drive 50 miles then take it out and place it in a small trailer and drive the same route. id even spot you the weight of the trailer and see which one uses more gas and has the transmission downshifting more. i think you might be very surprised.

 

i think it tunes the truck down alot but i dont have any numbers and i'm sure the company will say it doesnt. heck we were still denying that the death flash tuned down engines when it was common knowledge it did - a lot. if it was me id just run the mid grade gas and screw the tsb. the knock between 1800-2500 rpm isnt going to be there with mid grade anyway so i dont think you'd need the flash. but id get it done if you run 87 gas. its kinda like a programmer you buy it changes the tune so its perfectly safe to run 87 octane.

 

So much for a 390 hp hemi. Glad I run a tune and have had this mds crap disabled for 2 years now.

 

I have a new engine being installed in my 09 right now (37000 on truck). It's under warranty and all I've run 87 octane over 90% of the time. Dealer never even questioned my octane levels. 1700# load is a joke in a 400 hp truck....IMO.

 

This is why I like this forum, I learn things. After reading this thread I went and got my manual out and indeed it does recommend 89 octane - don't know why I didn't see that before as I have read the whole book cover to cover (yes I am one of those people). I have pulled lots of mountains with a load running 87 octane. However, after looking at the hp/tq curves, I am always in tow/haul mode and ususally in 3rd gear in my attempt to keep the rpms above 2000 all the time going uphill. My thinking is with 392 gears and keeping the rpms up, maybe I didn't do any damage with pinging as I don't hear well. I will be running 89 octane from here on...

 

Have run only 87 octane in the '03 and the '09 and I tow loads up to 9,000 lbs. with zero issues on either one of them. It there is any detonation the timing will be adjusted to eliminate the problem and all you're out will be a few HP. Have never heard one knock from either truck. Oh, by the way the old truck has 136,xxx miles and the newer one has 58,xxx miles and they run just fine. I do know what detonation is and used to run my Buick GN to see 4 degrees of knock retard on the scan tool for maximum performance. Tuned the fuel to achieve this. Momenatry, light detonation (until the timing is retarded) will not harm an engine. Heavy prolonged detonation will. It will usually eat away at head gaskets before it harms the other components and to some extent the cylinder heads as they are aluminum...

 

and why are they installing a new engine? just curious.

 

i worked on these engines about five days a week for almost 7 years at a dealership and that's a new one on me. rebuilt quite a few hemis even more 4.7, seen head gaskets in perfect shape and pistons that were ca-ca.
seen quite a few hemis with gouges in the pistons and lots of hot spots id guess that were running 87, but i said it before nobody fesses up to it after their engine is toast.

 

That does not sound like detonation to me, but it could be, but would not like result from using 87 octane fuel. These modern engines (if the the PCM is correct) will adjust the timing to end the detonation so I find it almost impossible to believe the damage you are seeing is from detonation. I only worked as an engineer on a few new model launches for all the big three as well as some of the offshore brands. Even launched a a few MBUSA models as well... In addition raced a few years with high HP turbo cars. The 87 Buick GN would retard timing and pull back turbo boost to get rid of detonation. I have seen as much as 12-14 degrees of total timing pulled out on those engines with a relatively simple ECM set up. I have seen detonation in these engines lift heads off the gasket and then blow the gasket out. Modern engines are way more advanced now days. If you have detonation in one you have a big problem with the ignition system. The manual says 87 octane is no problem so no warranty claim is going to get denied based on the owner saying they used 87.

From the 2011 Ram Manual...