? My manual says to run 87 for daily driving and 93 for tow/hauling...

But, yeah when I try to give it all it's got for passing or the like it does hold back, I thought it was the shifting issue. I've got 93 in it now, left over from a towing trip. Maybe I'll try standing on the gas pedal on the way home and see what happens.

 

Sounds like a fuel pressure issue throw a gauge on it and go for a drive if under wot you see it drop below 55psi that's your problem

 

HO has a higher compression ratio, which is why high octane fuel is required. Higher Octane fuel does not give you more power or better mileage. It allows engines to have higher compression ratios because it prevents pre-ignition (pinging or knocking) as the fuel/air mixture is compressed. The higher compression ratio allows engines to get a greater amount of energy out of the fuel (bigger bang!). Modern engines have sensors determine when knocking is occurring, and then back down the amount of fuel that is squirted in, retard the ignition, etc. which is why you get "poorer mileage and less power" with regular fuel in an engine designed for high octane.

 

Elite,

While the engine can run on 87 octane Chrysler recommends 91. The following is taken directly from the owners manual.

The 4.7 HO engine is designed to meet all
emissions regulations and provide satisfactory
fuel economy and performance when
using high quality unleaded gasoline having
an octane range of 87 to 91. The manufacturer
recommends the use of 91 octane
for optimum performance.
Light spark knock at low engine speeds is not harmful to
your engine. However, continued heavy spark knock at
high speeds can cause damage and immediate service is
required.
Poor quality gasoline can cause problems such as hard
starting, stalling and hesitations. If you experience these
symptoms, try another brand of “regular” gasoline before
considering service for the vehicle.

 

Thanks Chris. It has been running much better with the 93 in it left over from the trip. I double checked the manual and I'm not sure where I saw the towing / non-towing fuel designation, but I did see the same thing you posted. I'll be sure to stick to a premium fuel from now on.

 

Been running 91 in it like the manual says and hasnt made a difference in the stalling out when I'm getting on it. It will still accelerate just very rough.