[NateNBeckie]

Ok, so yesterday on my way home from work, I decide to pull the vacuum line off of the EGR to see how the beast runs. I didn't care if it threw a CEL, I just figured it would stop exhaust gases from getting back into the intake and keep things a little cooler and cleaner. I unplug the vacuum line and plug it up, then start the car. It ran just the same, but it never threw a CEL. I dorve it all the way to work this morning and it still didn't give me a CEL. So I'm thinking it could be one of 3 things:

1. The computer doesn't care for some strange reason (highly unlikely).

2. The EGR valve is stuck open so regardless if it has vacuum or not, it is open and the computer doesn't care, as long as it sees flow when it needs it.

3. The CEL is burnt out. (I really doubt this). I didn't look to see if it comes on when I turn the ignition on, and I should have now that I think of it.

I don't have any spare vacuum line laying around to put on the EGR and give it a little suck at idle to see if it affects it. I am betting on number 2 above, but I want to see what you all think. It will help me in starting to figure this out.

Thanks,

-Nate

 

[Capital Punishment]

I just figured it would stop exhaust gases from getting back into the intake and keep things a little cooler and cleaner.

The EGR system actually lets your engine run cooler.

The EGR valve is stuck open so regardless if it has vacuum or not, it is open and the computer doesn't care, as long as it sees flow when it needs it.

The computer would throw a code EGR: Flow Excessive.

 

[silvapain]

which vacuum line did you disconnect? the line from the EGR solenoid to the EGR valve?

The MIL will not be activated until the EGR system fails on two consecutive key cycles. It does the check right when the car starts, so if you left the engine running when you disconnected the vacuum line, two key cycles may not have happened yet.

Capital Punishment is right, the MIL will be activated if the EGR valve is stuck open.

 

[NateNBeckie]

which vacuum line did you disconnect? the line from the EGR solenoid to the EGR valve?

The MIL will not be activated until the EGR system fails on two consecutive key cycles. It does the check right when the car starts, so if you left the engine running when you disconnected the vacuum line, two key cycles may not have happened yet.

Capital Punishment is right, the MIL will be activated if the EGR valve is stuck open.

I disconnected the line from the EGR valve itself.

I didn't know it took 2 key cycles. I did stop the engine before I disconnected it. I have only cycled the key twice since I did this (once after doing it and once this morning), so if it was going to give me a CEL it would do it if I went out and started it now.

I figured it would give a code for excessive flow, but I needed to make sure.

The EGR system actually lets your engine run cooler.

How would it let it run cooler? Exhaust gas is way hotter than what is coming into the intake. Maybe I've been way wrong about this for years.

 

[silvapain]

Exhaust gas contains very little usable oxygen, what is needed for combutsion. It does, however, contain alot of Nox and Cox (Nitrous oxides and Carbon oxides) which are combustably inert.

The EGR system is designed to reduce NOx and Cox emissions by heating them up and breaking them down more, and to reduce combustion chamber temperatures by taking up volume that could be filled with combustable oxygen.

EDIT: keyboard is messed up and not keying r's and i's.

 

[Patrick Norris]

The egr system in the gen III doesn't throw codes or CEL often. Most times when you get a 401 EGR Insufficent Flow code the light will come and go. When I removed my egr all together it only would cause a CEL if I were driving like a old lady and still only about once a month.

 

[silvapain]

THe EGR system primarily functions when cruising at constant speeds and during decelleration. That may explain why it threw codes when you drove like a little old lady. During acelleration the EEC goes into an open loop and ignores the EGR signals.

 

[NateNBeckie]

Originally posted by silvapain@Jun 9 2004, 10:42 AM
Exhaust gas contains very little usable oxygen, what is needed for combutsion. It does, however, contain alot of Nox and Cox (Nitrous oxides and Carbon oxides) which are combustably inert.

The EGR system is designed to reduce NOx and Cox emissions by heating them up and breaking them down more, and to reduce combustion chamber temperatures by taking up volume that could be filled with combustable oxygen.

EDIT: keyboard is messed up and not keying r's and i's.

Oh, that's where the confusion lies. I completely agree with this. The temperatures I was talking about was just raw intake temps (before it gets into the cylinder). I didn't specify this when I wrote it. Sorry.

Need a new keyboard? I've got tons of em'.

 

[silvapain]

It's the Universities' keyboard. I have three brand new ones at home.

I really should be doing my research project now, but maybe I'll waste more time by replading the keyboard.........