I have been a memeber for years and have spent the last few years enjoying the ongoing DPF Delete/Fuel Mileage/Warranty threads. It never seems to get old reading them!!

A few months ago I removed the DPF filter from my truck. I was happy with the results and, with the help of many in here, I went to the next step by removing the DOC (Diesel Oxidation Catalysts) last week. I have also now installed a new muffler and tailpipe from Magnaflow. I am very happy with the modifications. The sounds, at the tailpipe, is great and I have the smell of my old LB7 back!! As far as performance, I'm not sure yet but I know it has improved. I didn't really make the change for fuel mileage but more for the longevity of my motor. One interesting observation I have had since all the modifications, especially the last of removing the DOC, is how much this truck does smoke. I have not modified my LB7 and it smokes considerably more than that truck. Now, I'll admit, my foot might be more to blame than the motor, but I think GM's '08 stock tune is much more aggressive than the '02 LB7 stock tune.

I am curious if anyone has an idea of what this has done to my HP/Torque levels. I'm running a Quadzilla S2 programmer on Level 1 (Stock Tune). I know stock means it should be at factory settings but opening up the exhaust has to improve the motor's ability to create HP/Torque.

As always, I apprecaite anyone who takes the time to read and/or reply to my posts. This group has helped me out a tremendous amount over the last few years!!

Greg

I have the smell of my old LB7 back!!

Same here. I love that smell.

...is how much this truck does smoke. I have not modified my LB7 and it smokes considerably more than that truck.

I've seen different results than you. I had an LB7 before my LMM and smoked a lot more on a stock tune than my LMM does on a PPE level 2. Do you have your EGR blocked? Once I blocked mine I stopped getting so much smoke.

Same here. I love that smell.



I've seen different results than you. I had an LB7 before my LMM and smoked a lot more on a stock tune than my LMM does on a PPE level 2. Do you have your EGR blocked? Once I blocked mine I stopped getting so much smoke.


can someone pls explain why blocking EGR results in less smoke? thks

can someone pls explain why blocking EGR results in less smoke? thks

EGR circulates "dirty" air back into the system, blocking it, stops the dirty air, which allows more "clean" air to burn. The diesel is burned more efficiently, producing less smoke that you see out the tailpipe. This is probably a very simple way to look at it. Chris

My LMM doesn't smoke at all up through level 3 on the Edge Race tunes, PCV rerouted, EGR unplugged, plate is still in the box. My Quad S2 would really smoke on the 90hp+ tunes, only ran a couple times, but 110hp setting would smoke as long as I would "lug" the engine some in 6th. But my mpg's also went up almost 2mpg just going from Quad to Edge. I never had any improvement in mpg's with the stock Quad tune, still had the turbo lag I didn't like with the "stock DPF truck". Chris

EGR circulates "dirty" air back into the system, blocking it, stops the dirty air, which allows more "clean" air to burn. The diesel is burned more efficiently, producing less smoke that you see out the tailpipe. This is probably a very simple way to look at it. Chris

Would blocking the EGR mean less regens???? That would be simple.

Would blocking the EGR mean less regens???? That would be simple.

Theoretically, yes, but you would need a tuner to turn off the codes or disable the EGR motor itself. So I don't know if blocking the EGR with a completely stock exhaust setup is possible, without CEL's, need a tuner? Chris

Same here. I love that smell.



I've seen different results than you. I had an LB7 before my LMM and smoked a lot more on a stock tune than my LMM does on a PPE level 2. Do you have your EGR blocked? Once I blocked mine I stopped getting so much smoke.
I have not blocked my EGR. I have looked at doing the modification but that seems a little involved and didn't want to press my luck.

Not sure how blocking it would help though. If anything, I think it would make it worse. With the EGR open the motor has some chance of re-burning unburnt fuel.

I have not blocked my EGR. I have looked at doing the modification but that seems a little involved and didn't want to press my luck.

Not sure how blocking it would help though. If anything, I think it would make it worse. With the EGR open the motor has some chance of re-burning unburnt fuel.


Do a search for what an EGR can put into the engine. Any perceived ability for reburning unburnt fuel is no reason to keep an EGR, IMO. The half inch of crude coating, can't be good in any way for your engine. Chris

Do a search for what an EGR can put into the engine. Any perceived ability for reburning unburnt fuel is no reason to keep an EGR, IMO. The half inch of crude coating, can't be good in any way for your engine. Chris
hey Chris, and I totally agree. I would like to take it out but that is beyond something I'm comfortable doing in my garage. My modifications are the result of a case a beer and a few friends of mine in the shop. This is still a nice truck and I there have been too many times we've jumped into something just to hear, right when you think you have it all put back together right, "hey...where did that part come from and does it need to go back in the truck..." :)

In my response before I was referring to the EGR, when removed, making the motor smoke less. I know it helps the motor run more efficiently and I'm sure will make for a cleaner/happier motor. I just don't think, when removed, that the smoke decreases.