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1999 Chevy Suburban Engine runs rough and dies.

Tiny
NEWNATE
  • MEMBER
  • 1999 CHEVROLET SUBURBAN
  • V8
  • 4WD
  • AUTOMATIC
  • 198,000 MILES
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?
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Tuesday, March 23rd, 2010 AT 8:56 AM

1 Reply

Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
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.
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Tuesday, March 23rd, 2010 AT 7:28 PM

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