There is alot of talk now about unpluging or blocking the egr on the 04 lly motors. Can a tech please state what effect this might have on normal operation? I have not done either and want to know alot more about it.

What you have to remember is that there are many instances that the ECM commands the EGR to be closed. So it operates normally in the closed position. There is no postive side as far as engine operation is concerned to having the exhaust gas recirculated. Also federal LB7's also do not have EGR's.


The benefits are that you will see an improvement in turbo spool up time and also you should see an improvement in fuel mileage as well. If you block off the egr cooling tube you will see cooler engine temperatures (when towing) because they use engine coolant to cool the exhaust gasses. This adds a lot of strain on the cooling capacity and in my opinion the cooling system isn't up to the task.


The main benefit is that you will no longer have the exhaust gasses recirculate through your intake. This will without a doubt increase engine life. The only reason there is an EGR on any vehicle anywhere is to meet emission requirements. If there were no emission requirements the egr would not exist.


The only real downfall is if you have a California emission truck you will get a check engine light. This still doesn't really effect anything other then you have an annoying light. The other downfall is you will no longer meet emission specs. Of course, reversing your mod will put it right back into specs.


The only other negative aspect is that if you block off the egr with a plate as opposed to unplugging it, you will increase warm up times. This might be a bit of an issue for us up north. At idle the engine also might not warm up to as high of temperature as it would without the plate in really cold climates.Edited by: Max Power

What I am looking for is what the ECM does when it sees the codes that are caused... limp mode of some sort? I understand the physical side of what is going on, I just don't know what the program inside the ECM does with its feedback or codes. Also, what is the ecm really looking at to initiate the codes. The only thing that I can come up with is a different temp at the turbo. The MAF might see a different airflow, but would need something to compare it to. Does it compare it to a trend in volume to throttle position?

where do you unplug the egr at

http://dieselplace.com/forum/forum_posts.asp?TID=13040&PN=1&TPN=12


This thread should help you out.


Dennis