I have a 2003 4.7 QC 4x4 with 86K miles. When I bought it last July, I noticed that it took alot of acceleration to climb hills at highway speeds, and seems to be getting progressively worse over the last few months. My husband thinks the engine might be too small for the weight of the truck, I am more inclined to believe that it is a mechanical issue. The check engine light came on recently, indicating the rear O2 sensor...which is sitting on my table, waiting for installation. Also have a tapping that is getting stronger & louder...suspect the rockers, as these Rams seem to have alot of issues with this. Presently getting about 12.9 MPG & like all Ram owners, would like to see more. Any advice would be appreciated!

 

I would say that there is a good chance that your catalytic converter is clogging up, and or breaking apart. If you have a cat efficiency code that is most likely it. The rear 02 is for emissions and doesn't effect the performance of the engine. The rattling you hear could be the converter. At the shop I work at (MI) we have seen alot more converter failures recently??? By the time we get the car/truck in it usually barely runs so a quick check is to take the front 02 out to give the exhaust a way out. Of course you can't go to far like that but it is a quick free test.

 

If it is the cat converter, how easy is that to replace ourselves? I have also heard or read somewhere that you can hollow them out?

 

Yes you can hollow it out....Not legally..And it is not fun trying to break the pieces up to get them out Some people use an air hammer with a long bit to get in there. Or you could cut it out and put in a pipe to replace it. Not sure it you have an emissions inspection where you are, but in MI we don't have them. Might want to check it to be sure that it is the problem before you remove it.

On most of the bad ones I see, the engine will bog at full throttle. Rev to a point and usually can't get enough rpm to shift and kind of "hang" there. If this is whats yours is doing then I would pull the front 02 and see if it gets it's power back with a quick run to be sure.

 

Yep, a clogged cat would account for everything you describe. You can omit the cat (cut it out - although it's not legal) if you're not an inspection state and use a $5 non-fouler to eliminate the code it will generate or simply replace the cat with another one. Magnaflow cats are very high flowing and not terribly expensive.

Although it's not a Hemi, the 4.7 has plenty of power for the truck unless you are towing/hauling regularly PROVIDED it's kept in good working order. Meaning a free flowing, unobstructed exhaust and a proper maintenance schedule is followed. It's also pretty important for both performance and fuel economy to clean the throttle body at least every 30,000 miles...

 

I swear I can clean ot the Tb every night and see a gain every time. Good Luck

 

I have heard if the cat is bad, it smells like rotten eggs...is this always the case?

 

It can, and it used to be the rule of thumb. But in these days of oil/gas companies running cleaner burning fuels via a lot of additives you really can't go by that anymore. Often there is no way of telling a mildly clogged cat short of it generating a CEL and as it clogs worse then performance will start to suffer.

The "rotten egg" thing would have held much truer when your father was your age...

 

Not to jack this thread but just for reference how many cats are one these trucks? Mines an 06 so it may be different but mine seems to surge while climbing rpms and im thinkin the exhaust is plugged up somewhere

 

Thanks for the great advice...going to pull the downstream O2 today & see what happens. Really hoping it is not the Cat, since I just put a heater core in this truck last month...getting expensive to repair/maintain.