1999 Chevy Suburban Engine runs rough and dies.

1999 CHEVROLET SUBURBAN
198,000 MILES • V8 • 4WD • AUTOMATIC
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NEWNATE
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My 99 suburban just started running rough all of a sudden. I did look at the codes and am getting a random multiple missfires. I did remove the egr valve and engine seems to run much better. When i plug the egr ports the engine stalls. I am thinking the engine was able to get more o2 with the egr valve removed through the port. I don't think the egr valve is bad but not 100% sure. Any ideas???
Also just ran engine with egr valve removed and received a o2 sensor failure bank 1 sensor 1. Is this because of no egr or is this actual problem?
Mar 23, 2010 at 8:56 AM
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FACTORYJACK
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The 02 sensor code was probably a result of the excess oxygen in the exhaust stream. It is quite possible, with the misfires, and the fact that it run good with the EGR disconnected that you have a restricted exhaust. Are the multiple misfires consistent with one bank or the other(even/odd cyls.), remove that sensor(pre cat) from the exhaust pipe and see if misfires diminish. Most common is a catalyst that breaks apart inside and starts clogging. This can occur at higher rpms, as bigger pieces are displaced with the velocity of air. It can also come on after a shutdown, when the particles settle in the bottom, and then progress with exhaust flow.
Mar 23, 2010 at 7:28 PM