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4.7L Exhaust upgrade help!

23K views 62 replies 8 participants last post by  sconnie89 
#1 ·
Hi everyone just looking for some input from those who have upgraded their exhaust on the 4.7L 2002 Quad cab. I want to do dual exhaust but I'm not strictly after sound only, would like to gain a little from the money spent. I like the sound and look of the Flowmaster 50 series but not sure how it compares to the 40 series or the Magnaflow. I'm kinda lost and don't know where to start! I have been reading that a Y pipe with single in and dual out is a good route for this truck to avoid losing low end torque?? Really just need a good setup with a deep tone and a few pony gains coupled with a CAI. Any input is greatly appreciated! -Chris
 
#52 ·
I'm going to fix the exhaust leak on the 27th. I don't know how yet lol. The exhaust is leaking at the band clamp. I'm going to first try wrapping the joint with header wrap, then installing the band clamp. The code I'm getting is a lean code on the rear O2 sensor that is right next to the band clamp. It's nothing to do with the cats or catalytic efficiency, so the non fouler's are working from what I can tell. I've done probably 1000 miles since the exhaust work.
 
#54 ·
Thanks. I'm going to try exhaust wrap first, if it doesn't work I might try that.

My CEL keeps going on/off due to the leak. I'm just happy it's not cat related. The truck is getting noticeably better mpg and seems slightly more powerful. I'm surprised to say that removing the cats is probably the most noticeable modification I've done performance wise next to the tuner. I'm getting about 22mpg at 70-75mph pretty easily currently. That used to be pretty rare maybe at 65mph.
 
#55 · (Edited)
Finally was nice enough yesterday to crawl around under mine.
My back 02 sensor is in a differant spot then yours Sean
The back sensor actually goes into the side of the cat itself,not in the pipe.
Not sure where in hell to mount a bung for my A/F gauge now,lol.
It says to mount it at least 18 inches downstream of the manifold and ahead of the cat.
My cats are roughly only 6 inches behind the manifolds,so to get the A/F gauge mounted 18" downstream of the manifolds,i'm well behind the cats.
Not sure how the A/F will work if it's behind the cats.
Kinda puts me in a bind for modding the exhaust,as i'm wondering if the non foulers are even an option on the later trucks with the sensor into the cat itself.
This is the first one i've seen where the sensor is actually in the cat itself.
 
#56 ·
Mine were the same hornet, the downstream sensors were in the center of the cats. Don't see why the non fouler trick wouldn't work there.

I tried exhaust wrap it was very difficult to tighten the clamp since the diameter was larger, and didn't seem to seal that well. Then tried wrapping the joints with tin foil a few times before putting the clamp on, this worked fairly well. Couldn't hear or feel any air around the clamps after but the code came back so it's still leaking. I'm either going to try a different type of clamp(maybe a donut) or move the rear O2 sensor closer to the engine by like 12" + or as much as possible.
 
#57 ·
I'm really interested in your progress.

After looking mine over close yesterday,the crossover pipe needs some work that's for sure.
So if you get your cel figured out,let me know,lol.
My cats just might fall off,and a new crossover pipe might go in,if you get your's sorted out:smileup:.

The code it's setting isn't keeping it from going into closed loop ,or sending it into limp home mode is it?

Rick
 
#58 ·
Yeah the downstream sensors don't really effect the performance at all,they just monitor emissions and compare a/f ratio to the upstream. But they don't effect how it runs. The easiest way to deal with this is to get a diablo tuner and have a custom tune and they can just turn off the rear sensors. But I refuse to give up the superchips because it's better than the diablo custom tune I had before. I just need to get a clamp that seals. I should have thought a head a little more too and not put the sensor right by the clamp. They say you should not put a sensor within 18" of a clamp, I wasn't thinking of that when we welded the bung in.
 
#59 ·
Just to keep you updated I figured out what I'm going to do as a fix for my leak. I'm going to replace all the lap joints/band clamps with these ball/socket joints:

http://www.jegs.com/i/JEGS-Performance-Products/555/31902/10002/-1?parentProductId=1353765

My light isn't on anymore, the tin foil helped but it's still leaking. The light was going on/off for a while and has finally stayed off. But once I weld in these new joints there's no way it'll leak.
 
#63 ·
I have read that if your truck doesn't have two exhaust manifolds, then dual exhaust is impractical, you may want to check to see if your truck does or not. I could be wrong about this. Also, if you don't have two manifolds, you can always do the dual passenger side exit exhaust, it's more unique and gives your truck an older hotrod look to it. Its what I originally wanted, but not within my current budget. Good luck!
 
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