Did we ever come to a concensus whether disconnecting the EGR's had any real positive effect on mpg's, engine/tranny temps, etc. It's a given that less soot is being recirculated through the engine during warmup, but some guys posted worse mpg's after disconnect, some better; some lower engine temps, some no change? Never seemed to achieve any real consistency, mostly seat of the pants opinions. http://www.dieselplace.com/forum/images/smilies/frown.gif

One thing I noticed, when guys upgraded their exhaust and removed the CAT, then disconnected their EGR's it was common to throw MAF sensor codes for too much air flow. http://www.dieselplace.com/forum/images/smilies/redface.gif IMHO this would indicate there is restriction or backpressure created by the EGR since once disconnected there is increased air flow which causes the PCM to adjust fuel rates, etc., to compensate. http://www.dieselplace.com/forum/images/smilies/confused.gif

While I like the idea of less soot, I'm not one to install plates or sticks, I need something simple I can leave in all the time for dealer visits. http://www.dieselplace.com/forum/images/smilies/wink.gif I've been rehashing whether to disconnect the EGR again, so yesterday I re-read the "EGR Disconnect" thread, yes all 67 pages, to digest it again. http://www.dieselplace.com/forum/images/smilies/wink.gif We learned a lot through that thread! http://www.dieselplace.com/forum/images/smilies/rockon.gif

All those posts got me thinking? http://www.dieselplace.com/forum/images/smilies/rolleyes.gif Since putting on my 4" MBRP cool duals and removing the kitty I have noticed a huge difference in turbo spool up and exhaust flow, dang truck sounds more like a jet. Also, there appears to be a lot more soot coming out the tailpipes! Hmmmmm? http://www.dieselplace.com/forum/images/smilies/confused.gif Is there another option for reducing soot in our intakes? http://www.dieselplace.com/forum/images/smilies/wink.gif

CAUTION: JJ HYPOTHESIS ALERT! Is it possible that by installing a high flow exhaust and removing the CAT and significantly decreasing the exhaust backpressure allowing for much faster exhaust gas flow can we "deprive" the EGR of a lot of the soot it previously had access to during the combustion process? http://www.dieselplace.com/forum/images/smilies/rolleyes.gif

Easier said, by pushing a significantly higher amount of air/exhaust through the engine and exhausting it much quicker is more soot following the "path of least resistance" out the exhaust versus being drawn back in for recombustion through the EGR? http://www.dieselplace.com/forum/images/smilies/confused.gif Is there any real way to be sure?

I thought about looking at the oil, but questioned if it is conclusive enough since we have positive crankcase ventilation as well which dumps crud back into the intake. OK, this is above my head! I just think this crap up, but it does beg the question! http://www.dieselplace.com/forum/images/smilies/biggrin.gif On edit, doesn't oil analysis count soot content? If so has anyone done O/A before/after exhaust/kitty removal with the EGR connected? We're going to have some soot due to the PCV, but if there is a substantial reduction of soot that would confirm the hypo above. I don't do OA so I'm in the dark on this.

IIRC when open the EGR only recycles a small percentage of the exhaust gases(25%+-), and mostly while getting up to operating temps then it closes, so it is not a constant application. http://www.dieselplace.com/forum/images/smilies/confused.gif

Those with OEM exhaust and running CAT's likely need the plate/stick to avoid PCM issues. However, if the premise above holds water those that have upgraded exhaust and killed their kitty's may be just as well off to leave the EGR plugged in, especially those that live in colder climates since it helps the LLY get up to operating temps faster. The EGR is there for a reason, not just recycling soot! http://www.dieselplace.com/forum/images/smilies/wink.gif

Just floating this for discussion. Could JJ be full of crap, always! http://www.dieselplace.com/forum/images/smilies/hihi.gif As always, be gentle please! http://www.dieselplace.com/forum/images/smilies/tongue.gif JJ http://www.dieselplace.com/forum/images/smilies/smile.gif

JJ wow! what a post!!:eek: I'll shed what very little I know... here are each of my fill - ups since new... I dont have very many so its easy to recall

all numbers in town... Pittsburgh area hilly terrain lots of stop and go's

tanks mpg change since last

1 13.3 none
2 13.3 none
3 13.7 unplugged EGR
4 14.1 installed plate - NO stick
5 12.7 no change but pulled 8K dutchman 200 or so miles
6 17.7 this final # is an estimate... based on previous tank needle positions.... also I installed kittly delete pipe AND Predator at 65 hp setting


So what Ive shown here seems to indicate that disconnecting the EGR for me, anyway, has no effect on MPG. The variance from 13.3 to 14.1 is irrelevant since there were no scientific consistancies... plus spring time may have introduces a warmer blend of diesel at the pump. And engine break in improvements in MPG may have started as well.

This current tank of fuel is remarkable. Im not sure what attributed to the improvements... but me likey:D :D

I assume its the kitty, and definately the predator on 65 tune... however... Ive been mashing the GO pedal since I tuned it... probably one hundred WOT's since it went in at 100 miles on the trip meter... it now reads 280 and the needle is exactly at 1/2 tank..:eek: Previously at that spot on the fuel meter, the trip meter consistantly read 210. ):h

So there you have it... I contributed NOTHING to your post!!:rolleyes:

Hello,
Not to confuse you even more, but... I read somewhere in a Chevrolet Service Manual, (I wish I could locate it to post here), how the EGR operates. It went on to explain how during light cruising speeds, (this is when the engine runs lean), combustion chamber temperatures spike, causing nitrogen oxides (nox) to form. This is one of the "emissions" the Feds and local governments wish to reduce. So, in an effort to reduce the high combustion temperatures, the EGR purposely contaminates " -:t " the fresh incoming charge, causing incomplete burning and thus reducing temps low enough to not create the nitrogen oxides. The "Cat" also plays a role by breaking down some of the Nitrogen Oxides into Carbon Dioxide and water vapor.

While I kind of feel guilty doing it, it will be done! I don't like the idea of "contaminating the incoming charge" in the name of emissions reductions. I don’t see why, (at least with the LLY engine), they can’t reprogram the Variable Vane Turbo settings to get the desired effect (lower boost at light cruise causing a rich condition)? But, then again, that’s why I’m not a highly paid Engineer. :rolleyes:

Dentman, just confirms what I read on that 67 page thread, mpg's are either up or down, no clear concensus. ;)

Diesel Day, I had read pretty much the same thing, I believe in the Disconnect EGR thread. Contrary to causing things to heat up, the exhaust gases actually have the affect of reducing combustion temperatures as you stated. Once the engine gets up to 210*+- the EGR closes and the CAT is relied upon to diminish most of the NOX emissions or something to that effect. :rolleyes: It's probably more complicated that I explained it but you get the drift. :)

We're really only talking about eliminating soot when the engine is not up to operating temps. In very cold conditions with the EGR open on a stock exhaust with a CAT I suspect more of the exhaust emissions are being recycled through the EGR versus trucks with free flowing "kitty less" exhaust systems. This was my premise. ;)

If I've reduced the soot by 50-75% for the 25%+- of the time the EGR is open I can live with that to have the added benefit of quicker heat up times. My "seat-of-the-pants" impression towing was the grade braking worked better with the EGR connected as well, but moreso at higher elevations when the outside temps were 50* or less, on long descents where the engine temps dropped below normal. Could it be the additional backpressure the EGR presents helps the engine during this function? :confused:

I'm just waiting for guys like Fingers, MaxPower, and others to read this and educate ol' JJ, again. ):h I can stretch things to meet my needs when I have to, then these guys bring me back to reality. As always I appreciate their patience and time though. But you have to wonder that if you reduce exhaust restrictions and minimize backpressure the ability of the EGR to recycle exhaust gases has to be diminished and the soot particle count reduced as well. JJ :)

As far as the grade braking goes, I read that Fingers verified that the VVT vanes do not close all the way if the EGR is simply unplugged, versus plugged in and using the Finger Stick. I would imagine that this is the actual cause of the change in grade braking performance since the closed vanes are what create the higher backpressure. Also, I don't think that the converter has anything to do with NOx emissions. I believe that it is only there to act as an "afterburner" to combust the increased exhaust soot caused by the EGR. Just my opinions and a few edumacated guesses.;)

So it sounds like disconnecting the EGR without plating/sticking does affect grade braking. Maybe I'm not as crazy as I thought?:o: Nah! ):h JJ :)

Diesel Day, I had read pretty much the same thing, I believe in the Disconnect EGR thread. Contrary to causing things to heat up, the exhaust gases actually have the affect of reducing combustion temperatures as you stated. Once the engine gets up to 210*+- the EGR closes and the CAT is relied upon to diminish most of the NOX emissions or something to that effect. :rolleyes: It's probably more complicated that I explained it but you get the drift. :)JJ,

I am going to throw my .02 worth in here also. Now let me prefact this by stating that I have not done the amount of research it seems that most of you have done regarding EGR valves in diesel applications, however I do have a through understanding of thier use in gasloine applications. I was for 12 years an ASE certified Master Automotive Tech and a licensed State of California Smog Tech. (The worst state in the country for emissions contorls) and feel I need to interject some insights into EGR operation here.

ON GASOLINE APPLICATIONS..... the egr valve DOSE NOT operate during cold/warmup operation, as it does not increase combustion temaptures. On the contrary it reduces combustion tempatures as stated above. The emission NOx is created by excessive heat in the combustion process and IS NOT dealt with by the kitty. The EGR operates, once the engine reaches operating tempature for the computer, during any throttle operation other than idle and WOT. IN most gasloine applications these systems have special controls which will also only allow its operation only when there is backpressure present in the exhaust system. In essence the EGR valve creates a vacume leak in the intake system which if done during warmup would be extremely detremental to the operation of a cold engine. It is, after all, enough of a problem with a warm engine.

That stated, I see no reason to believe that it's operation on diesel engines should be any different than on gasloine engines. It is still after working towards the same goal. As I understand it's operation on our motors, the EGR valve operates once the engine enters closed loop operation under cruise/part throttle operation only. The reason I can see for this is due to the turbo. On any turbocharged engine, during boost conditions, you do not create engine vacume, rather the turbo creates pressure in the intake system. Now with this in mind, if the EGR were to be operating during boost conditions, then you would be loosing boost through the EGR valve, just like you would through the waste gate.

Remember that what I am stateing here is based on my knowledge of EGR operation on gasoline engines, and I HAVE NOT fully researched its operation on diesel applications and if someone has facts that dispute these statements, please post them so that I may learn also.

Lastly, bearing all this in mind, I have the blocker plate and finger stick in place on my truck with no change to millage, or noteable change to preformance. I installed them praying for a noteable increase in millage, and probably will be removing them. I think the benifits of the system operating outweigh the negative aspects. And as a last note, gasoline engines produce carbon instead of soot during combustion which has been going through those EGR valves for 30 years without a negative impact on engines other than maybe plugging up the passages for the EGR system.

IMHO

John

In regards to Soot in the intake, all you have to do is look at a VW TDI or any older GM diesel that has been running the cooled EGR for 50K+ miles and you will see why we do not want that crap in our intake manifolds. The constriction amounts to ~50% passage blockage easily. I have seen some as bad as almost completely blocked...

Personally, my EGR is blocked and a stick is on the way. All of my applications that use a cooled EGR are defeated in some way or another.

VW TDI or any older GM diesel that has been running the cooled EGR .
cooled EGR????

The EGR on most modern diesels is run through a cooling jacket prior to re injection into the intake stream.

The displacement of O2 in the entake reduces the cumbustion temps and thus the formation of NOx emmisions.

The CAT finishes the combustion process of CO and other hydocarbons but requires additional O2 to do its job. Usually, a diesel has a lot of extra O2 going out the exhaust.

The EGR on our diesels is active nearly all the time. (except at WOT) Backpressure in the exhaust is kept above intake boost via the VVT, so there is nearly always flow. The EGR valve itself is trimable to allow just the right amount of gas flow to reduce temps per a table stored in the ECM.

I have seen little to no performance increase. But that is not why I blocked the EGR. I was looking to reduce the heat load from the cooling jacket. (overheat issues) To that end, it has reduced the heat load, but not enough to cure the overheating problem.

I am not fond of passing the soot back into my motor.

The Stick solves the issues that arise from free flowing exhausts and reduced backpressure. With or without the plate. That is a totally different topic IMO. However, many in need of the Stick for fixing the exhaust codes go for the plate too while they are at it.

In the "Disconnect EGR" thread it was posted that on our trucks the EGR's operate until the truck reaches operating temps, 210* IIRC. The EGR helps our engines heat up as well. I don't know why they are different than gassers, though I presume it may have something to do with how much hotter the combustion process is for diesel versus gasoline. :o:

Can't argue the soot removal point. Brings up a good question though. Before EGR's in diesel engines was soot never a problem in the intakes? Being that combustion is taking place within a cylinder wall I would suspect it's been an issue before as well, just a bit worse with EGR. Remember the EGR isn't a full time operation, it's only open til operating temps are reached then it closes and the CAT is supposed to do its job. Also, the LLY has positive crankcase ventilation which recycles fumes/gases from the crankcase back through our intakes. :confused:

So is nobody going to tear my high flow exhaust/no-kitty theory apart? My premise is that with a high flow/kitty-less exhaust the majority of the heavier particulates in the exhaust (soot) are flowing much faster and going to follow the path of least resistance out the exhaust versus being pulled back thru the EGR for recirculation/recombustion. :p:

FWIW, the inside of my 5" SS MBRP exhaust tips turned black immediately after installing the MBRP cool duals and removing the CAT. Seems like it took longer for my OEM exhaust with CAT. JJ :)

I guess it is time to do some serious research about the operation of the diesel EGR. Apparently there is a difference in how they worked as compared to Gasser EGR's.

Let you all know what I find out.

John

Like Fingers, I believe that the EGR is operable to some point at all times. In any non-EGR applications that I have torn down for rebuilds, most of the intake manifolds leading into the heads are just as clean as they came from the factory. Any EGR application has been caked with carbon deposits. Ever look in the chimney of a woodburning stove where the chimney becomes cold outside?? The exhaust gases cool to a point that the creosote starts to form on the walls and choke down that chimney. The intakes on EGR motors look the same way...

As for our motors PCV, the LLY has a new system of venting the crankcase. On the LB7, there was a draft tube that went down the front of the motor and drained out to the road. The crankcase "gasses" were not recycled at all, but rather dumped onto the road or sprayed on the underneath of your vehicle/trailers/etc.... On the LLY, there is now two check valves (one on each head) with a tee into the intake manifold pre turbo (atmospheric side). You can see the inlet of this system if you take the snorkel off the motor. You will also see that there is an amount of oil film there as well. Most motors tend to have this type of setup, so I wasn't suprised to see this new system on the new truck for better "emmission" control. With this type of setup, you cannot tell when the motor is starting to show major blowby, and there will now be a coating of engine oil inside of all the CAC lines and CAC itself. Maybe this could lead to reduced air cooling later in life, but time will tell. Not much you could do about it, and also not sure that you would notice a difference if you rerouted that.

My $0.02....

nassdmax, good posts, got a couple of questions. On the EGR engines you've rebuilt were they gas or diesel? I know there is a simple answer to my earlier question about diesel engines leaving soot in the intake side without EGR's since most of the LB7's didn't have EGR's. ;)

I don't want to get too far off topic with the gas/diesel comparisons, but feel it does add something to this discussion. Even though diesel engines combust at much higher temps than gassers, with diesel fuel we don't have the benefit of fuel additives that clean the engines like gassers do. I've read that some blow-by, not sure how much, is common on diesel engines which is why we may have diesel fuel, soot, other crud in our crankcases. It's hard for me to imagine a diesel engine, with/without EGR being soot free even in the intake area. Wrong? :confused:

Any diesel mechanics out there that have torn down engines running high flow exhaust/no kitty's want to weigh in here? Most of us don't have the benefit of having looked into our engines to see exactly what is happening. The answers out there, :help2: ? JJ :)

This thread seems to have taken a bit of a tangent so I'll help continue that line. It seems that many of the issues that we are wrestling with regarding soot in the engine and plugged intakes has been well recognized and addressed with our TDI, VW owners. We have one (2001 Jetta TDI), and I can assure you that recycled PCV in concert with cooled EGR WILL plug intakes. The remedy for the plugged intake is removal and cleaning, not a simple job. The prevention is well documented over in the TDI forum. Bascially, the PCV is either re-routed out the traditional way ("elephant hose" is one simple way) or a more complex method of separating the oil content out of the gasses BEFORE the gas is reintroduced into the intake is also described. The other method that is used to reduce the ill effects of EGR is to "reset" the ECM using a computer hook up to the ECM (VAG COM) and reprogram the ECM to minimize the amount of EGR that is returned to the engine. Are either of those methods appropriate or feasible for our trucks? (Mine is a 05 GMC CC LLY)

Diesels are what I have been commenting on...

Nassdmax, willing to take a stab at my high flow exhaust/kittyless theory? :rolleyes: Have you noticed any less soot build-up from engines with this setup?

Talking about the carbon build-up takes me back to the "good ol' days" when we used to blow the carbon out of our engines by getting out on the highway and nailing the accelerator! Sounds like it might have some benefit with our LLY's! :D

Continuing on with the carbon build-up discussion, I used to put a little water down the carbeurator of my old Ford six banger to remove the carbon build-up on the pistons and valves. Mama JJ would keep her foot on the accelerator to keep it from stalling while I would give it short drinks of distilled water. I'm wondering if WI on our trucks would in effect accomplish the same thing? :confused: Appreciate the feedback. :) JJ

Bumping this back up with some additional intel. When starting cold in the mornings the exhaust rumbles for about 2-3 seconds then sounds like a big air pump, no black smoke. The other day I started the truck and proceeded to air up the tires. After a few minutes I was back by the exhaust and the whooshing air sound went away and went to a deep rumble. First time I had let er' warm up enough to actually hear the change. Was that the EGR closing? :confused:

Once I'm up to operating temps and I stop for a few minutes when I remote start the truck there is an initial ploom of black smoke with the whooshing sound, then its gone and the whooshing sound goes away immediately. I'm assuming this is the EGR closing since it senses the engine is up to operating temps already. Make sense? :confused:

One more thing I have noticed. You can blow a lot of soot out of the exhaust if you nail the accelerator, similar to the good ol' days when we used to blow the carbon out of the engines. ):h After I do this I can actually see the stainless steel in the interior of my 5" tips again. Wee haa! :D

Still no input on my high flow exhaust theory? :rolleyes: Must be rock solid then! ):h Later. JJ :)

my truck has egr mods and the cat must have fell off somewhere. can here the chage in exhaust sound. i think it is lly turbo changing and just more noticable with out the cat

The hissing is when the vanes are closed and the EGR valve is usually open. The deep rumble is when they are allowed to open a bit. The EGR valve is usually closed then. You can usually hear the ECM do the EGR flow test through the exhaust note. About 3-5 sec rumble, then 3-5 sec hisss, then usually another short rumble session.

Wait, so if the egr is blocked will the exhaust rumble more and not hiss? I assumed the hiss was the turbo changing it's vanes. More rumble would be good.

Don't know. I assume if you unplug the EGR it would rumble more since the EGR will not cycle when codes are set. Vanes don't go full closed either. Hmmmmm

Just wondering if anyone knew why the Cummins HPCR engine in the new Dodges doesn't require an EGR valve to meet emission standards?

:offtopic: Hello I am a new member, I have a 2005 lly with a preditor at the 65 horse setting and a four inch exhaust system, I optioned for a muffler in hope I would not have this code issue. But I throw them at least once a day. I have read about a stick? or a egr blocking plate? I have no idea what the stick is or where I can get one. I asked my local chevy dealer and he looked at me like I was crazy. If anyone could post a reply or email me I would be greatful. thank you

Welcome to the place.

Ordering and install info for the Finger Stick is here. (http://dieselplace.com/forum/showthread.php?t=21428) Doing a search on EGR and you will know more than you ever thought possible about Dmaxes and EGR.

Enjoy

:offtopic: .... I have no idea what the stick is or where I can get one. I asked my local chevy dealer and he looked at me like I was crazy.

I can just imagine how that conversation went. :lol:

VDIES: Do you carry the Finger Stick?

Dealer: "A what!?", never heard of it - do you have a part number? What's it do?

VDEIS: It keeps the the tucks computer from throwing codes when you block off the EGR or put on a larger exhaust. Alot of guys are using them.

Dealer: Block off the EGR??? You can't do that!

VDIES: The guys (gals) on the internet said you can.... Uh Oh! Ahhhh......never mind!

Dealer (after VDIES leaves): WTF was that guy talking about??

As you can see by my signature, I have done a fair amount of mods to my truck. When I start up in the morning with the EGR blocked, kitty scared off, and Finger's stick, I still have the rumble then to the hiss. After warm up it's back to a rumble and a hiss. I was told that the change in sounds were something to do with the VVT turbo and not the EGR. Obviously all I heard prior to my mods was just the hiss, or what I thought was just the hiss probably due to the fact I was listening through the stock exhaust.

I don't know if it helps MPG's to block the EGR, but if it will keep my oil cleaner and less contaminents being scraped around on my wear parts during operation, Logic has it that it will prolong the life of my engine and I don't really care about if it increases the mileage or reduces my EGTs. I have done other things to my truck specifically for those issues. Make sense?

the alternating rumble/hiss combo at startup is from Vanes in turbo opening/closing to warm engine/turbo components.... the increased hiss is from removing kitty...less back pressure..... quicker spool up time from EGR plate, and no codes from Fingers' stick... in that order:D

OK, since nobody seems willing to weigh in on my original post I've been doing some investigative work on my own to either validate or invalidate my theory. Being "meck-a-nickel-ally" challenged I had to rely upon what I've read on the DP for ideas.

I recalled reading a post from Got Juice a couple of weeks back. He had installed "the twins" on his truck and driven several hundred miles(?) round-trip to check performance, mpg's, etc. To his surprise his oil was clean, he could hardly see it on his dipstick. He attributed this to the extra volume of air being pushed by the twins. :rolleyes:

So ol' JJ got to thinking. The premise of my theory involves more air as well. Seeing as I just changed my oil on April 8th why not check my oil to see how it looks. I've driven over 1400 miles since switching to Mobil 1 T&S 5w40. Guess what? My dipstick is clean, just a very slight hint of tint to it. Usually my oil turns black pretty quick after changing it. :confused: JJ's happy! :ro)

So what does this tell me? Honestly I don't know! Someone with a technical background please shed some light on this. This was my first oil change since putting the MBRP 4" cool duals on and "kitty kill". My EGR is still connected, I remote start my truck and let it run for 5-10 minutes before hitting the road. I run Power Service every tank. Just some additional intel in case it matters.

Anyone else running free flowing exhaust minus the kitty seeing similar results? JJ :)

I can almost 100% confirm that after installing the Finger and EGR blocker plate, my boost dropped by around 3psi for normal cruise speeds. Can't tell if it changed any of the max spikes by that little. I think the steady state drop makes sense, considering the finger stick is making the computer THINK that it is getting X amount of return flow from the exhaust, and it adds that to what it thinks it needs to run the turbo at for pressure? Anyway, using analog gauges, I can easily confirm a difference of around 3psi lower under normal town and freeway driving conditions (no load) with the finger/blocker installed.

-JM

I can almost 100% confirm that after installing the Finger and EGR blocker plate, my boost dropped by around 3psi for normal cruise speeds. Can't tell if it changed any of the max spikes by that little. I think the steady state drop makes sense, considering the finger stick is making the computer THINK that it is getting X amount of return flow from the exhaust, and it adds that to what it thinks it needs to run the turbo at for pressure? Anyway, using analog gauges, I can easily confirm a difference of around 3psi lower under normal town and freeway driving conditions (no load) with the finger/blocker installed.

-JM

I'm no expert here - but, if what you say is accurate, if there's is less boost could it mean that the engine is not working as hard with no EGR because of a better fuel burn (which equals more HP), therefore there is less boost because it is operating more efficiently and doesn't require as much boost to pull the load??

OK, since nobody seems willing to weigh in on my original post I've been doing some investigative work on my own to either validate or invalidate my theory. Being "meck-a-nickel-ally" challenged I had to rely upon what I've read on the DP for ideas.

I recalled reading a post from Got Juice a couple of weeks back. He had installed "the twins" on his truck and driven several hundred miles(?) round-trip to check performance, mpg's, etc. To his surprise his oil was clean, he could hardly see it on his dipstick. He attributed this to the extra volume of air being pushed by the twins. :rolleyes:

So ol' JJ got to thinking. The premise of my theory involves more air as well. Seeing as I just changed my oil on April 8th why not check my oil to see how it looks. I've driven over 1400 miles since switching to Mobil 1 T&S 5w40. Guess what? My dipstick is clean, just a very slight hint of tint to it. Usually my oil turns black pretty quick after changing it. :confused: JJ's happy! :ro)

So what does this tell me? Honestly I don't know! Someone with a technical background please shed some light on this. This was my first oil change since putting the MBRP 4" cool duals on and "kitty kill". My EGR is still connected, I remote start my truck and let it run for 5-10 minutes before hitting the road. I run Power Service every tank. Just some additional intel in case it matters.

Anyone else running free flowing exhaust minus the kitty seeing similar results? JJ :) color of oil is no indacation of oil quality!

ssgreg, I agree! My point was that normally after I change the oil within 500 miles it turns dark. It still has its lubricating properties, just showing the effects of combustion gases, soot, blow-by, etc. My point was that after 1400 miles with the MBRP duals and no kitty the oil is still essentially clear, which for me, hasn't happened before. :)

Over the weekend I looked inside the CAT to see just how much restriction it was creating. There is a small mesh screen that all the exhaust has to penetrate before entering the CAT, then it flows through the OEM exhaust/muffler. I can see how it creates a considerable exhaust obstruction. I also had the truck checked for codes, none! :D Later. JJ :)

I'm no expert here - but, if what you say is accurate, if there's is less boost could it mean that the engine is not working as hard with no EGR because of a better fuel burn (which equals more HP), therefore there is less boost because it is operating more efficiently and doesn't require as much boost to pull the load??

Possibly (if I understand what you are saying). :wtf1: ):h

:blahblah: Honestly, I think what is happening, is that you are actually developing slightly less horse power (VERY slight, mind you) because your computer is expecting some boost pressure to be coming from the exhaust (and getting feed back from the EGR that the flow is there, but it is being tricked by the finger stick), so it backs off the turbo vanes. Even though it is exhaust, there is still some O2 there that can be reburned and adds to your precompression, and I'm not sure if it would be more or less O2 with lower pressure, but more pure intake mixture. Anyway, it is probably immeasureable, in all reality, and it isn't a huge deal, I just thought I'd mention it. I'm not saying it is good OR bad, just that it is there. Shrug.

-JM

Possibly (if I understand what you are saying). :wtf1: ):h

:blahblah: Honestly, I think what is happening, is that you are actually developing slightly less horse power (VERY slight, mind you) because your computer is expecting some boost pressure to be coming from the exhaust (and getting feed back from the EGR that the flow is there, but it is being tricked by the finger stick), so it backs off the turbo vanes. Even though it is exhaust, there is still some O2 there that can be reburned and adds to your precompression, and I'm not sure if it would be more or less O2 with lower pressure, but more pure intake mixture. Anyway, it is probably immeasureable, in all reality, and it isn't a huge deal, I just thought I'd mention it. I'm not saying it is good OR bad, just that it is there. Shrug.

-JM

What is happening is the exhaust backpressure that was normally pumped into the intake from the exhaust at cruise is not. Measured backpressure at cruise is about 10 PSI. The turbo would build little or no boost on flat land if not for the false boost coming from the exhaust manifold.

Boost is not power. If you are not smoking at cruise, you have enough air.