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Old 08-11-2015, 01:15 AM
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Location: Saskatoon, SK
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What happens if I temporarily leave the EGR blocked off?

I know it serves a purpose but here in Saskatchewan, Canada emission testing isn't a factor. My Catcon is shot, so I'm thinking of cuttin it out and putting a straight pipe in...

any other way to do it opposed to cutting it out? As for noise, I'm not too concerned but what would be the outcome of drilling a hole right before the Catcon, would that help with pressure release and could it be permanent?
Old 08-11-2015, 09:26 AM
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Really don't think your neighbors or townspeople want you to straight pipe it.

I've heard of people cutting out a cat, breaking up all the crap in there until it's small enough to come out the end, and thereby emptying their cat con and putting it back in. Relieves the backpressure IN THAT PART OF THE SYSTEM, keeps the noise down. Keep in mind that some of those catcon bits may have traveled downstream and could be clogging up either the resonator or muffler. You just don't know until you investigate.

Personally, I've never done this. Don't know how the Saturn engines are designed w regard to back pressure--I would think the engine management algorithms would be set up with some back pressure in mind.

If your catcon is wasted, your rear 02 sensor is going to read low. Aside from the P0420 catalyst efficiency, I THINK there is an effect on the long term fuel trim -- someone else please chime in. I THINK the car runs overall leaner as a result, with the front 02 still controlling the A/F mix, but skewed to the leaner side. You should definitely research this on the web before taking the above for gospel. If I'm actually right, you may want to invest in a rear 02 simulator, which simulates the rear 02 sensor reading and thereby makes the PCM happy and deals w the lean issue.

As for blocking off the EGR, your combustion chamber temps will rise and create the NOx gases (as per a recent post by Keith) which are bad for the environment. It's been done, but I don't remember how the engine responds to the equivalent EGR Valve stuck closed. I know when the valve starts sticking, you get alot of weird stuff going on when you decelerate. RPMS were oscillating across a huge range during decel, the car would stall, be impossible to start for about 3 minutes, then start right up like nothing happened and run fine. Search the forum for some of my older EGR related posts using EGR and decel as keywords. I also don't remember if the normal position of the EGR at idle is closed or open -- i believe closed. Then comes the question---is it receiving a 5V to hold it closed (meaning normally open is the native state) or is it not receiving any control voltage to stay closed (normally closed).

If the answer is normally closed, just unplug the connector and it will stay closed on its own. Again, you'll have to research this.

Sorry, my brain is clearly mud this morning. Been driving only S cars since 1992 and suddenly I can't remember how half the shayt works.

Someone else please assist in cleaning up my swiss cheese of a post and getting Banger the answers he needs.

Sorry for the lame post.

Last edited by derf; 08-11-2015 at 09:31 AM.

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