I have a 2004 Hemi Ram QC with an annoying knock that has plagued me since I purchased the truck. It has 1000 miles on it as of this writing, and the knock only occurs under certain conditions, those being:

1. The engine is under a load, eg going up a hill.
2. The engine is not straining to pull the load, eg the engine RPM's stay between 1800 and 2500.

I have read in the engine manual that there is a certain amount of "spark knock" allowed at low RPM's. It also says that spark knock at high RPM's is something to be concerned about. Is anyone else suffering the same symptoms on their Hemi? If so, have you come up with fix for it?

 

i would say try a higher grade fuel like a tank of 91 and if that don't cure it then i would take it back to the dealership and complain!!! i ran mine hard at the track tonight with 87 in it and never once had the pinging/knocking you are talking about!!! definately something to be concerned about if the higher grade fuel don't fix it!!

 

I put a tank of 91 octane in it last night. It hasn't helped yet, but I have only got 6 miles on it since the tank was filled. I will give it some time. If by the end of the second tank of 91 it hasn't stopped I will call and take it in to the dealer.

If I change my spark plugs to a cooler plug, such as the Autolite 3923, will it void my warranty?

 

no it shouldn't but it shouldn't ping with the stock ones as they were put in by the factory, i would be complaining if that tank doesn't fix it and you shouldn't have to change it from factory to fix something, ya know?! just my own opinion!!! good luck, hope the gas fixes it!!

 

I agree that you have a problem that needs to be fixed by the dealer. Actually the truck should run without knock with 87 octane. Running 89, which is the recommended grade for the Hemi for optimum performance should stop it also.

I suppose that you have tried different brands of fuel from more than one location, as it's possible you could be getting sub-standard fuel from one location. It would still be my contention, however that the truck should run without knock even on 87, I've never used anything else, and whether I am towing or just cruising around, I never have that problem.

It may be a timing problem that the dealer can adjust in no time, but I would take it back and complain.

 

I have a new post called Hemi "Tick" asking if the sound I talk about here could be the same thing. What is the Hemi "Tick" I hear about on the forum's out there? Could it be the same sound I describe here?