why do people disconnect the egr is it for someone having a specific problem or does it prevent a problem does it have anything to do with extended idling and the fuel not being burned totally

 

Some bunny hugger came up with the idea that if you reroute some of your exhaust back through the engine combustion process, that would make for more complete combustion and cleaner air. It is a nice idea, but in practicality, it has some unintended consequences like many good intentioned ideas.

The Exhaust Gas Recirculation Valve Control controls the amount of exhaust gases recirculated back to the intake. It is a proportional solenoid with a built-in position sensor. The Valve Position Sensor is needed to give the control circuit feedback to achieve desired travel position. The Exhaust Gas Recirculation Valve Position Sensor is a variable resistance pintle position sensor that makes position measurements of the exhaust gas recirculation valve control actuator.

It is the suspected source of a lot of problems. If you turn off your ignition, the valve closes. If you disconnect the electrical lead to the valve, it stays closed and you can see if it improves performance. However, if you disconnect it, the computer senses the disconnect and instead uses some default parameters to keep running.

Some people report improved performance others see no performance change.

 

I can't speak for whether or not to disconnect it, as mine still works fine, but I have a pretty good level of experience with EGR stuff as I was an Inspector when I was permanently in Pennsylvania. I am also trained as a Chemical Engineer, but that doesn't make me a complete expert.

EGR is employed on Diesels to cut Nitrogen Oxide Emissions. If it's used properly, the EGR reduces the combustion temperature, which on a diesel also works to cut noise.

What happens, particularly with diesels, is that carbon blocks up the ports or worse builds up on the valve, causing it to stick. Diesels have always had the tendency to "carbon up" during extended idling. That is why in the pre-smoke trap days, trucks used to put out the characteristic cloud of black when pulling away from a stop or starting up cold in the morning (because you idle a diesel, particularly a turbodiesel, down to avoid oil coking).

If the truck is allowed to idle too long, carbon will build up in the tops of the compustion chamber and ultimately through the entire exhaust. Since the 6.0 has a lof of high-tech stuff on it, some of the items can eventually get buggered up by the carbon. I don't know how good the Variable-Geometry Turbo bears up to it, but I know the EGR valves get carboned up. When this happens, the valve starts to stick. If it sticks shut, you'll prpbably get a Check Engine Light. If it sticks partially open (the usual problem), the truck will idle poorly, perhaps smoke a bit, and may result in turbo surge under slight loads. Turbo surge gets into another sensor that gets uppity about carbon, the Exhaust Backpressure (EBP) Sensor.

The way to avoid carbon problems usually is to use good fuel and to avoid excess idling. You have to idle it some, though, because otherwise you'll be out a turbo or worse. It's a matter of balance. I like to let mine warm up for a few minutes, and if I work it hard I'll give it a few minutes to cool down.

I wouldn't recommend it, but an old "technique" people used to do in the smog era to degunk the pollution gear involved giving it a good, hard run. The other tactic, of course, is to disconnect the EGR. Provided the valve is completely shut when you do it, it will probably stop any idle hijinks as the EGR valves seem to get gunked up more than the EBP sensors do. I imagine that is due to the size of the exhaust supply line to a given component. Anyway, if I had to guess, disconnecting the EGR valve would result in a slightly louder idle, slightly higher Exhaust Gas Temperatures, and probably a slight decrease in fuel economy. Now, of course, none of us ever told anyone how to disocnnect the valving, and you didn't do it either. It just fell out. When the plug just happens to "fall out", though, the computer throws a hissy fit and puts the check engine light on. I imagine someone gifted with a milling machine could make a plate to block off flow to the valve and reconnect the plug. I think there's another valve associated with the EGR as well, though. There's a thread somewhere else on the matter if you're interested. If that was done, you'd keep the PCM happy and get rid of the EGR. Like I said, though, I didn't suggest that or come up with any way to upset the bunny huggers with machine guns in Washington.

 

Tampering with pollution controls is, of course, not entirely legal. Like I said, mine has not failed on a routine basis yet. It acted really odd once, and I fixed it by taking a short run down the highway at elevated speed. I cleaned it right out, and the thing runs like a top again.

That being said, I have a suggestion for those of you who may work with reflashers. Why can't the computer simply be reflashed with an EGR strategy that says "keep it shut all the time". Since the valve is electric for both control and feedback, it must ultimately get its orders right from the Computer Network. I'm sure it's illegal, but I'm not totally sure that those chips keep the truck meeting all emissions at all times anyway. Just a thought, because it would be great to leave the plug in there so it looked stock, avoid having to tear anything apart, and just have the problem go away. I don't know the details on the control limits on the computer network or anything like that.

 

Cowboy Brett, If you disconnect the EGR, the computer will throw codes and use a predefined set of parameters for operation. If you are in the People's Republic of California, where they are required to have a different flash, then it turns on the CEL.

 

SBV45-
I am aware that pulling the plug will set the Check Engine Light or at least a code. Does it not turn it on in the 49-state models then? I'm in Arizona, and the truck I have is from Pennsylvania, original flash.

In thinking about it, many vehicles today have engine monitoring that knows if the EGR passages are blocked anyway. You'd probably still be ratted out by the computer if anyone downloaded it. I was under the impression that everyone got a Check Engine Light with it unplugged. A code can be tolerated, provided nobody is going to scan it.

Actually, my EGR has always worked fine, so I've left it on and been gentle with it. I was just trying to figure a way to help the other folks escape the demons of the EGR system. I also keep an eye on it in case I would ever have any problems.

I have some OBDII training, but the 6.0 is Diesel, and it is running on CAN technically, not OBDII, at least according to my service manual. When I was in PA, Diesels did not receive any emissions inspection, so I'm working off bits and pieces. In the oldest of old days, you could stop an EGR by plugging the vacuum line, but as the computers advanced, they put position sensors on them, so then you had to plate or restrict the passageway to test for malfunctions lest you flag the Check Engine Light. Nowadays, they put temperature sensors on the intake manifold at the EGR port and some vehicles watch for changes there to see if the EGR works. I don't know if the PSD does that or not, but judging from your post there, it would appear so.

I can't in good faith condone just disconnecting it unless it causes a lot of problems for folks. Mine's working fine for now, so I'll leave it until problems come up. All of my other vehicles have their original smog gear on them as well, with no problems. When my EGR failed on the Merc, I replaced it. That being said, if people keep smoking out EGR valves every couple thousand miles, it seems silly to keep throwing the parts at it. I understand why folks might want that plug to fall out in a situation like that, particularly if the truck is always missing when work needs to be getting done. I was actually looking to find a way to streamline the process so it wouldn't involve just leaving stuff hanging out disconnected. What is needed is a redseign of the valve or a change to the combustion strategy to avoid this problem, but I really don't know enough about their work in the matter to know where the root cause of failure is. All I know is that people are having them flub up if they idle a lot because of carbon.

 

Read the LONG EGR thread---disconnected the EGR on my 05 modified with the Banks, AFE and Magnaflow and guess what. Lost power and mileage so after almost 2 weeks hooked it back up. Try it for yourself and see.

 

cant you just unplug it and plug it into another egr near a heat source to fool computer

 

Cowboy,
Like SBV mine has fallen out and no Check Engine Light. Dang thing just fell out!!! Throttle seems more responsive but XMonitor seems to show max boost around 27lbs. I used to see 29 or so as max but overall seems just as strong. You've got the right idea though, if it ain't broke, don't fix it.

 

Mine is connected, but I did have it fall out once. No it did not cause an engine light.

This out of the service manual:

The California Air Resources Board (CARB) began regulation of On Board Diagnostic (OBD) for diesel vehicles sold in California beginning with the 1997 model year. OBD requires monitoring of emission-related components. The Malfunction Indicator Lamp (MIL) is required to light and alert the driver of a malfunction and the need for service of the emission control system. A Diagnostic Trouble Code (DTC) is associated with the MIL identifying the specific area of the fault.

So there are flashes for California and for the 49 other states.

 

Mine feel out 3 days ago and haven't had a check engine light yet. Can't tell if performance / mileage is any different yet....

 

Would it work better by pulling the EGR valve, inserting a plug then mount the EGR on top still pluged into the computer?

 

The plug would need some o-rings for seals. Talk has been for a plug but noone has come up with one.

 

I bought up the plug idea because I make one, with orings and A hole in the top so you can mount the EGR valve. I have not installed it yet because I have to take the truck in monday for steering box leak, and reflash. I'm A maintenance mechanic and have A full machine shop, I got bored one day so I removed my EGR valve and made A print of the valve. It took a week to make, I started out with A 3.5" round by 6" block of alluminum and turned it down on the lathe.

 

Sounds like a garage buisness in the making, maybe make a dozen if it works and market it as a EGR "test plug" like the test pipe bypass for the cat?