1moreamp

WoW I got lots of help now lol... Thanks guys for your input. Are you all Cali smog inspectors? just kidding, I thank you all gratefully for your input.


I have parts to go either way, but i also have a 2003 whole engine core here I am looking at without EGR. hence all my query about it. my local smog guy told me I could replace my meager 4.8L with anything up to a 6.0L without referee, and he was reading from his book when he told me I could do that. < great guy huh? >
His one caveat was that it all be 100% stock GM. no headers, no special air induction setups no bypass's etc...So I am shooting for a stone stock engine build using on the best 2003 and later engine parts externally< internally All forged guts like Gm use to build them >

1moreamp

By chance could any of you folks post a picture or a part number of an EGR sensor?
I have never seen one before and on my little truck I only see the EGR solenoid that is controlled by the ECM, but I don't see anything resembling a EGR sensor anywhere.
I always though the EGR valve was temp controlled, so forgive my ignorance if I am missing something.
I even went to the service schematics for the entire engine and don't see anything labeled EGR except the solenoid control valve on tube connecting the exhaust to the intake.
Now I do understand that the ECM might have some sort of current sense circuitry inside the ECM on the control leads out to the solenoid that will detect if the solenoid goes open circuit as a fault, or if the coil burns out or if the device in removed. I get that possibility since GM does monitor a slew of info in the ECM.

As you can possibly tell by my name I have an electronics background, so I am puzzled by the whole EGR sensor thing when i can only see the control valve that actually does the EGR function by ECM command.

I dread the thought of having to reuse my old intake and exhaust manifold just because it was in use way back in 2000, even though in 2003 it was obsolete by GM and Cali standards.

and thanks again to all for your kind info and help...

Wheelman916

I do not know if your specific application will have a sensor. But if the EGR is computer monitored, removing it will throw a "Check Engine" code... and any check engine light will cause automatic fail of a smog test. If you deactivate the monitor in the ECU, the ECU will report the EGR functionality as "not ready" and you will fail.

Most EGR systems are primarily inspected visually, and manually tested for functionality. Techs will notice it missing before even bothering to plug in to the OBD port. The under hood emissions label will tell the tech what to check for. If the emissions system on the engine doesn't match what the label tells them should be there, and there are no other labels from CARB or BAR explaining the changes, then you fail visual.

If the underhood label is missing, they can reference their computer system for the correct diagram.

Often, legal emissions systems modifications will include additional underhood labels. For example, legal engine swaps have a BAR label stating what engine is currently in the vehicle and what that engine originally came from. For add on changes like superchargers, for example, Saleen Mustang's come with their own labels that specify the changes to the OEM Ford emissions control system.

Standard emissions label example:


BAR motor swap label example:


Saleen modified emissions label examples:

1moreamp

Great info thank you

I'm not trying to get around Cali;s rules, I just want my upgraded engine to not be a CARB BAR nightmare after all the effort I went to build it correctly.
I remember what I went thru a number of years ago when I upgraded a old Dodge four wheel drive pickup from a stock straight six to a stock V-8. Cali made me smog it every year for no good damn reason at all. It was a stock setup all the way, no hot rod stuff at all. It was like I had angered the Gods or something just because I put a stock V-8 setup in a pickup truck.
And every smog guy I went to was freaking out looking for alterations because it had a BAR tag on it. That is why I went to so much trouble to make sure this engine was 100% exactly anatomically correct for its year model of issue by GM.

After looking over the entire schematic for the engine control system I am sure the ECM controls the EGR valve off its sensory inputs for temp, MAF, and MAP etc. But there is no sensory feedback from the valve itself back to the brain like you see for the IAC, and TPS sensors. So unless Gm included some form of basic current sensing in its control output from the ECM there is no way the ECM can tell if the EGR is anything but plugged into the brain nothing more. I can see where this could be bypassed by a simple load resistor to fake out the brain that its in circuit since there is no real feedback like the IAC, and TPS. Those devices use encoder feedback info in digital back to the brain to indicate actual real data for the ECM to operate with. So making the ECM think there was a EGR valve connected would be as simple as placing a proper load resistor in circuit at most so the brain thinks an EGR valve is connected.
No wonder why people block them off all the time and ebay is selling port block off kits like hot cakes and for stupid money too...Its one of the simplest ways to increase gas mileage on any vehicle, since EGR actually drops engine vacuum and loads the engine with poor fuel to air ratio issues. EGR does one thing I know of well. It helps to warm up a cold engine on start up quickly, along with dumping all sorts of exhaust crud thru the intake system supposedly to be re-burned again a second time. A good operating air injection cat system will handle all this properly the first time. So I think I understand why GM dumped the whole EGR system back in 2003 now. besides saving money GM's motors were passing smog without an EGR system on the dyno's so they just stopped building them that way and GM just pocketed the money, Plus Gm has mileage quotas to meet nowadays so I am betting they picked up the phone and called their buddies in Washington DC and got a variance for better gas mileage, No EGR since it increases gas mileage and engine efficiency to remove EGR from the vehicle...


Thanks again to all for your help and my apologies for jacking this thread ...

1moreamp

Just wanted to thank everyone one more time. I took everything all of you told me and went looking into ECM programming and found validation of pretty much everything you guys said, along with how GM got to drop EGR valving in 2003.

It would appear that once the 58X reluctor went into engines and larger memory into ECM's GM was able to electronically advance and retard timing to the extent that the old EGR valve system was not required any longer. Seems they were able to control ignition timing to the extent that they could reduce NOx pollution via timing, instead of choking the engine with exhaust to cool off the NOx production on the exhaust side. So while they don't use EGR valving any longer they do impart huge timing restrictions to achieve the same goal.

And I found the sensor you all mentioned in the valve assembly being driven by 0 to 5 volt PWM control with some form of linear actuation feedback to the ECM. This can be worked around though, as its not as sophisticated as it appears on the surface. The sensor will give a certain output for a given input from the 0 to5 volt PWM control. This is then compared inside the ECM. This actually probably improved the old EGR valves operation to lessen its impact on performance and improve on its overall pollution control, while not hosing up the engines regular operation like it used to in the old days. Still a bummer though as they traded one devil for another it would seem...

Thanks again to all...