Got a free header for my DD 2000 and it has no provision for the EGR tube. I don't mind deleting it but I don't want to stare at the CEL light. I know MS will solve it, but I'm not installing it yet.

So how do I fake an EGR signal to the ECM.

 

Can't you just run a resistor in-line to simulate a signal? That would cost you about...... $0.03. Just measure the voltage with an Ohm meter and find a resistor (or two) to match that reading and solder it in-line.

 

Sounds good. Some one got a 99-00 in running condition they can figure out what I need? Mine is currently in many pieces.

 

The next question is, does the ecu detect a constant on or off signal from the egr as a bad egr?

 

Ooooo..... that's a good question, and one that I never even would have thought of. The plot thickens.......

 

I believe the EGR code also checks for a change in engine vacuum with it open vs closed.

I have my egr solinoid still on the IM but with it blocked off where it goes to the exhuast. I never get CELs for it (knock on wood) ...but i guess I could make it unblocked. It is looking for change in vacuum, it doesnt know if it is exhaust air or ambient air.

 

You could mount a small air filter on the EGR inlet port on the intake manifold and leave the EGR valve on so that it takes in fresh air instead of exhaust.

 

I bet it also needs positive pressure like the header would give it...right?


And how would it meter it? It would be introduced after the MAF so it would be un-metered air causing a lean condition. Maybe the ECU compensates for that???

Your right, the plot thickens.

 

Hmmmmm.....

 

doubt it could tell the difference if its only measuring difference in manifold vacuum.

 

The EGR valve wouldn't need positive pressure since the manifold is under vacuum when the valve opens. Good point about the unmetered air. I don't think it needs to be metered as the amount of recirculated exhaust is not directly measured. The ECU uses the factory "boost" sensor to measure the IM pressure change when it opens and closes the EGR valve. If you wanted to have it metered as intake air, you could tee the air source from the valve cover hose which connects to the intake after the MAF/AFM.

 

lol i forgot there are people here with mafs

 

Only on my DD

 

i got a CEL today for EGR . i tried running stock ecu, injectors, maf and just open my egr port to atmosphere. I didnt have a problem with unmetered air, but after 2 drive cycles it thru the code p0470... egr

I just said screw it and bought the egr pipe for the FM manifold. hopefully i will be fine after that.