Blocked EGR now car is smoking?
TECH Senior Member
iTrader: (3)
Joined: Oct 2006
Posts: 7,564
Likes: 4
From: Decatur, TN (N-W of Athens)
Originally Posted by Razor_Blade
I'm also pretty sure that any tuning involved in egr removal only involves removal of the codes, so that the ses light doesn't stay on.
Originally Posted by Formula350
It didn't make any sense to me to be honest. If there's that much pressure in your exhaust that it's bleeding into the intake through the EGR, I think something else is up.
The intake tract is under vacum. The exaust is under pressure. Under the right conditions, the computer sends the signal to open the egr valve. When the valve opens, exhaust gasses are pulled into the intake, where they are redistributed and sent back into the cylinder with the air and fuel.
Originally Posted by Formula350
If you removed the SES light code, then the EGR would still turn on and run. You edit when it turns on and off, in multiple categories. Same with AIR.
Maybe so but it's the same result. If the valve is removed and blocked nothing happens when the valve is commanded open. The only result is the code and ses light. Editing the command is only a way to keep the ses light off.
Originally Posted by Enforcerws6
Not to mention the egr works off of the gasses in the manifold and lets them get back into the intake so how in the hell would that make a difference in a head gasket you are both outside of the chamber so it wouldnt bleed out any more gas and the little it lets in the intake will never be enough to cause any issue. Most older sbc if you pull the egr out the intake passage in completly clogged up with junk and dont work anyways and they are not blowing head gaskets. Without forced induction you cant get anymore into the cylinder unless you change pistons or something and Physics takes over for getting rid of it.
Originally Posted by Razor_Blade
No offense intended, you offer a lot of good info at times and allways try to help, but you really really really need to study up on exactly what the egr does. You do realize that there were millions of miles logged on small block chevys, before smog control was mandated by the government? I have a 94 sonoma in my driveway that will hit 300k in a couple of months, the egr has been blocked on it for the last 100k miles.
I'm also pretty sure that any tuning involved in egr removal only involves removal of the codes, so that the ses light doesn't stay on.
I'm also pretty sure that any tuning involved in egr removal only involves removal of the codes, so that the ses light doesn't stay on.
What is the compression ratio in those SBC's.. bout average 9:1. The LT1..10.4:1. Little bit hotter Cylinder Temps, reverse cooling allows this to work easier, but it still gets hot.
Now take a look at the LT4..10.8:1 CR BTW..NO EGR!!!
Makes you wonder, doesn't it...
Here's why..
The LT4 came with a larger Factory Cam, and the profile of that Cam allows the Cylinders to bleed out the excess pressures from combustion without having to use EGR, one of the functions of it on these Engines.
I understand EGR very well, I understand these Engines even better. Yes I know the EGR helps with Emissions to lean it out a little bit, that is how I ended up with a blown Head Gasket right after I put in my Hotcam in my first LT1. It was functioning perfectly..and leaned it out. I deleted it, got it re-tuned, and it ran like a champ. The EGR in this Engine also functions to get rid of some of the excess pressure and also to actually cool the Cylinder Temps down during Combustion by introducing some Exhaust into it, instead of just Gas and Oxygen. Less Fuel to burn=cooler Cylinder Temps. The Stock Cam in the LT1 is not large enough to adequately bleed these pressures off, sometimes resulting in blown Head Gaskets due to high temp. I have seen it, that is why I say that.
Yes, plenty of people take it off and Tune it out, I would Tune it a little rich just to be on the safe side.
Anyone can do what they want to do, I'm just throwing advice out there..
TECH Senior Member
iTrader: (3)
Joined: Oct 2006
Posts: 7,564
Likes: 4
From: Decatur, TN (N-W of Athens)
Originally Posted by Razor_Blade
Maybe so but it's the same result. If the valve is removed and blocked nothing happens when the valve is commanded open. The only result is the code and ses light. Editing the command is only a way to keep the ses light off.
Originally Posted by the_merv
that is how I ended up with a blown Head Gasket right after I put in my Hotcam in my first LT1.
So let me get this right, running a stock cam without an egr will lead to a blown head gasket and now running larger cam with an egr will also cause a blown head gasket?
There is now way for an egr to bleed off cylinder pressure. Even if it did, the egr is only operational in light throttle cruise situations. It does nothing at idle or wot. If the egr valve was intended to bleed off cylinder pressure, (which it can't) did you ever wonder why it doesn't come into play when cylinder pressures are the highest?
Yes, a properly functioning egr will SLIGHTLY lean out the engine, that's why there is usually a drop in mpg after egr removal. Adding a larger duration camshaft only reduces the effect of the egr, because less exhaust is brought back into the engine, due to lower manifold vacum. Adding headers and a free flowing exhaust also reduces the effect of the egr, due to the reduced amount of back pressure pushing the exhaust through the egr valve.
Keeping in mind that the egr is only commanded open in part throttle cruise situations, you should be able to see that you theory just doesn't hold water. I would bet the farm that your blown head gasket had absolutely nothing to do with presence, or lack of an egr valve.
Originally Posted by Razor_Blade
Keeping in mind that the egr is only commanded open in part throttle cruise situations, you should be able to see that you theory just doesn't hold water. I would bet the farm that your blown head gasket had absolutely nothing to do with presence, or lack of an egr valve.
We could go back and forth with this, mine could of been a freak thing, who knows..
I was just throwing advice out there through some research and experience.
Originally Posted by the_merv
Actually.. after looking at it, EGR working was deemed that was the cause. I was leaving a Stop sign when it went, not even racing at all. We even had it tuned a little rich.
We could go back and forth with this, mine could of been a freak thing, who knows..
I was just throwing advice out there through some research and experience.
We could go back and forth with this, mine could of been a freak thing, who knows..
I was just throwing advice out there through some research and experience.
Agreed! I've made my stance clear, so I won't take it any further. Do keep in mind, that there are also others who may have considerable experience and I for one usually research my facts before publicly disagreeing with anyones opinion.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Five Reasons the Camaro Was the Most Pivotal Player in the Pony Car Wars 2.0
Brett Foote
10 Reasons the LS7 Is GM's Most Extreme Naturally Aspirated V8 Engine Ever
Verdad Gallardo It's cool. Could of been a freak thing from the usual norm.
That whole Engine was a freak..have fun with it Corey.
Hopefully my 6.6l runs the same..I'll be cleaning the **** stains from the Seats for a little bit before I get used to it..
That whole Engine was a freak..have fun with it Corey.
Hopefully my 6.6l runs the same..I'll be cleaning the **** stains from the Seats for a little bit before I get used to it..
TECH Senior Member
iTrader: (3)
Joined: Oct 2006
Posts: 7,564
Likes: 4
From: Decatur, TN (N-W of Athens)
that's why there is usually a drop in mpg after egr removal
And Merv, I think it was a freak of nature as you said. I don't think the pressure would be great enough to blow it while driving normal. If it doesn't go out when beating on it, well you know the rest
Launching!
Joined: Dec 2004
Posts: 284
Likes: 1
From: Hebron, Oh
I ran a zz4 cam with no EGR or AIR, just a cat., and passed emissions no problem. The extra overlap of the cam helps create a self egr effect, drawing in exhaust gases during overlap. Moved on to a bigger cam and will find out tomorrow if it passes.
For fack sake, then a supercharger would blow a head gasket every time it was installed, Merv i think "****" just happened, not trying to start anything up again but that is just what makes sence to me.
