2G Don"t disable the EGR valve

[InterceptorF]

I have been fighting my GST for a while now with drivability issues. I decided to put the EGR circiut back on the car and VOLA! it fixed all my idle issues, drivabilty came back and now I am confident in the car making it home. I don't know why I ever took it off but I am glad I decided to put it back on!!

 

[bryanwheat]

If it was functional under WOT, I feel like it would be a boost leak as well as messing with AFR's.

It helps increase mpg's a bit. Your turbo is recycling enough gas's I feel. A lot fresher air too.

This is correct. There would really be no way for it to function at wot because the pressure in the intake would just likely overcome the pressure in the exhaust manifold and push air thru the passage from the intake to the exhaust.

 

[polarmoment]

If it was functional under WOT, I feel like it would be a boost leak as well as messing with AFR's.

This is correct. There would really be no way for it to function at wot because the pressure in the intake would just likely overcome the pressure in the exhaust manifold.

Sorry, but that's not correct at all.

Exhaust manifold pressure in a turbocharged vehicle is, with few exceptions, always higher than intake manifold pressure- sometimes by as much as a factor of 3 depending on how restrictive the turbine housing is. 2:1 is pretty common among modified performance engines, meaning pressure in the exhaust manifold is about twice that of the pressure in the intake manifold.

What I was referring to though is cooled EGR introduced in front of the turbo. Large volumes of it. It's not theory, it does work and it does make a substantial difference in the knock threshold of the engine. It's all in the SAE paper I referenced.

I wish there were an easier way to make it work. The main concern IMO would be the homogeneity of the charge (compressor wheel would fix that) and whether to tune compensation by detection or assumption.

 

[synthetek]

Haven't cleared the code yet.

You should try that first, sometimes a check engine light can be triggered by something that is a temporary condition and it might be OK now. If you clear the code and it comes back then you can start testing/replacing things.

 

[ishnish]

The "problem" is that you're car is possibly outputting slightly more gasses out the tailpipe. Just block it off and disable the cel. You can also remove the mdp sensor now and wire in a map sensor

Is that what the "recirculation malfunction" means? What does MDP mean??? Lol

You should try that first, sometimes a check engine light can be triggered by something that is a temporary condition and it might be OK now. If you clear the code and it comes back then you can start testing/replacing things.

Okay sure thing then I will try that. I'll keep you guys posted thanks.

How do I test the EGR and the MDP?

 

[rEclipserGST]

MDP = manifold differential pressure

 

[DSMnoobsause]

I have my egr removed and am staying Nutral in this debate. But I will link info I have found about Egr valves and the function.
Engine emissions systems - how they work and why

 

[Mitch41]

Ok just to clear something up the Evo 1 and 2 both come without an egr valve. The Evo 3 come with egr valve from factory, but they are actually disabled!
So how necessary do you think it could be

 

[ishnish]

Thanks rEclipserGST, now do you know how to test the EGR solenoid and MDP?

UPDATE: Guys, my check engine light went away on it's own. Now I really don't know what's up? Is this a good thing? This is so odd..

Don't make fun of me but I just figured out that "exhaust gas recirculation" malfunction means "EGR" malfunction... I feel like an idiot now.

 

[synthetek]

If it doesn't come back in the next few weeks then don't worry about it, probably just had something to do with installing the new ECU, or readiness monitors or something.