EGR valve

JAMChevy · March 14, 2005

I’m thinking of bypassing the EGR valve on my Silverado and using it only when I go to emission test, I have done it on my first truck which was Ford and the engine ran really smooth,better then with the valve pluged in. Have any one of guys done it and do you think the computer on the Silvy will register the missing EGR valve?

Cool Zr2 · March 14, 2005

Bad idea, it needs the EGR valve, the pcm will throw codes and the motor idles wired.

Ben · March 14, 2005

Federal crime to remove or modify smog controls.

Not state, but federal law, so all states in the union and territories.

You also might cause a lean burning condition and retard advance condition (less power).

EGR (exhaust gas recirculation) puts exhaust gases back into the intake gas charge. Poisons the mixture so it won't burn to hot.

If it burns too hot, more NOx and the computer will think too lean. So might try to increase the amount of fuel, but then the O2's will see and tell too rich. Mixing it up.

The hotter burn will also tell the computer to back off the ignition timing to save the valves.

With today's tightly integrated computer controls, it's best to leave the system intact. Maybe tune it for better performance.

Like the over sized can to trap oil mist from the PCV valve. The smog control is still active and working as planned, just has the gas go through a cylinder that traps the oil mist (tars) and only "air" goes back into the intake system.

redvett · March 14, 2005

I’m thinking of bypassing the EGR valve on my Silverado and using it only when I go to emission test, I have done it on my first truck which was Ford and the engine ran really smooth,better then with the valve pluged in. Have any one of guys done it and do you think the computer on the Silvy will register the missing EGR valve?

<{POST_SNAPBACK}>

What year and model is it . Chances it dosent even have an EGR on it. An GM vehicle with throttle by wire dosent have an EGR valve.

99Silver6.0 · March 15, 2005

I think 02+ trucks didnt have EGR. The 02 PCM I am running has all the EGR crap disabled when I made my tune with Edit. And I took off all off the stuff anyway. Just take all the EGR crap off if you want, and have the EGR codes deleted with a tune. You can get EGR block-off plates from any f-body performance site.

JAMChevy · March 15, 2005

Hmmmmm...alright. I do not want to get in troble with the law,so I guess I'm not doing it. Thanks anyway guys.

redvett, my truck is 2004 Silverado with 4.8L motor. I,m not sure it does have the EGR valve I bought the truck used two months ago and have not had the time to look under the hood yet.

I tell you one thing though I love the Silverado much better then the Ford I had,the only thing I wish is that it sits little more higher then what it is.

Thanks again

99Silver6.0 · March 15, 2005

Hmmmmm...alright. I do not want to get in troble with the law,so I guess I'm not doing it. Thanks anyway guys.

redvett, my truck is 2004 Silverado with 4.8L motor. I,m not sure it does have the EGR valve I bought the truck used two months ago and have not had the time to look under the hood yet.

I tell you one thing though I love the Silverado much better then the Ford I had,the only thing I wish is that it sits little more higher then what it is.

Thanks again

<{POST_SNAPBACK}>

04 trucks dont have EGR.

redvett · March 15, 2005

Hmmmmm...alright. I do not want to get in troble with the law,so I guess I'm not doing it. Thanks anyway guys.

redvett, my truck is 2004 Silverado with 4.8L motor. I,m not sure it does have the EGR valve I bought the truck used two months ago and have not had the time to look under the hood yet.

I tell you one thing though I love the Silverado much better then the Ford I had,the only thing I wish is that it sits little more higher then what it is.

Thanks again

<{POST_SNAPBACK}>

JAMChevy, If you have throttle by wire it has no EGR. The new EGR's are electronic and modulate open and closed. The are very efficent. With out it you will have sparknock and the PCM will retard ign. Glad you like your Silverado enjoy.

dr9672723 · March 15, 2005

I had a '93 Acclaim a while back which I removed and plugged the EGR hose from the valve. A short while later I got the check engine light. I wondered how on earth it knew I disconnected it, and later found out why. There was a vacuum solenoid valve which the computer periodically opened to apply more than the usual amount of vacuum to the EGR valve. After activating this valve, the computer looked for a lean condition immediately, to confirm the valve was working. When it didn't see that, it assumed my EGR valve was not opening.

Not saying anyone's GM EGR system works this way, but just thought that was interesting.

If you do remove your EGR valve, the previous poster is correct in saying you wioll have higher combustion temperatures, which may result in spark knock, hence retarded timing and worse mileage.

The old EGR systems when they first came out in the '70's were crude, and it's no wonder cars ran so much better with them disconnected. They are much better controlled these days.