EGR Tech Question

Whosoever

Whosoever

Lurker
Sep 15, 2007
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Southern California
Ok so here in Cali we have to deal with smog checks on a 2 year basis or so... I have taken my car to get smogged and it shows high NOx. What does that mean? He said it could be EGR or my cat. I do recall my car throwing a EGR code a while back but my question is when and EGR goes "bad" what is actually wrong with it? And on a scale from 1 - 10, how hard is it to change/replace/fix this bad dog while the engine is still in the car? Thanks yall!!
 
CyFi6

CyFi6

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Oct 11, 2007
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The EGR can have several things wrong from misrouted vacuum lines, faulty electronics, sticking valve etc. It can also be clogged with carbon build up internally.

An easy way to check if its clogged/a valve problem is to apply full vacuum directly to the egr valve with the engine idling, if the engine starts running really rough and wants to die out, then the valve is actuating and the passages are not clogged.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EC&P=16

That link will show you how to test the entire EGR system. First thing I would check is the vacuum line routing.
 
Whosoever

Whosoever

Lurker
Sep 15, 2007
56
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Southern California
Ok I tried the vacuum test and it does in fact run rough so Im guessing my EGR is functioning ok? So my next step is to get the car really hot so the cat can do its thing and then try to smog it. Any other suggestions?
 
CyFi6

CyFi6

Aliens.
Oct 11, 2007
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That just tells you that the valve itself is working and the passages are clear, you still need to make sure the lines are routed properly and your VSV and vacuum modulator are working properly. If they aren't, the valve will not open when it is supposed to if at all.
 
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