First off I have a 2000 Z-28 M6. My problem all started out of the blue. I had been raining on my car all day, i started it up and took off from work. About a mile from work my car started running rough, real rough. To the point where i could only go about 25 mph. My SES light started flashing on and off rapidly. Lucky my grandparents house was near by and I have an extra car there. I took it there until I could work on it. The next day I barrowed a Code Reader from work and got 2 codes, the first was that on the left bank, the upstream o2 sensor had high voltage, the second was the downstream sensor had low voltage. I cleared them and started the car back up. The car was still idling rough. Then the SES light came on and i got another code, this one was totally different from before. It was random cylinder misfire. After work, me and a coworker went to work on it somemore. I bought a spark tester from work and i had a code reader with me. We went and the first thing we did was clear the code. THen we started the car up. Still running rough. We checked all the wires with the tester and they all had spark. Another code came up, cylinder 1 misfire. We cleared that and went to drive it. The car ran well until a couple of blocks away and it started running rough again. We kept the car running and pulled over, my coworker went and checked the spark while i checked the code. THe code again was random multiply cylinder misfire. Then i cleared the code and sat there for a couple of minutes. I put the car into first gear and took off, she ran fine. I took the car back to my grandparents house for the night. The next day i drove the car to work, at first the car ran rough, then i sat at a stop light and then she ran fine. At work i took out #1 and #3 plugs (easiest to get to) and they looked fine, except that 3 had a chip in it. So I drove the car for about a week without changing the plugs, (had to fine time). The car would run fine then right when i start it up, it would run rough. I changed the plugs, I put 41-985 iridium delcos in, but what i took out wasnt. THey were 41-952, which delco doesnt make nemore. They changed it to a 41-932. So i thought that was the problem in the begining. So after I spent 2 hours changing my plugs, i took my car out for a drive. She ran better then she did when i first got her. I thought that i solved my problem, negative. I let her sit for a couple of hours and unitl i had to go back into town. I let her warm up for about 3 minutes, during that time, the car started misfireing again, this time worse then before, and again the SES light was flashing on and off like the first time. I turned the car off, then right back on, and she was fine. The next day i drove it to school, it ran fine. THen after school, i went to the mall, when i went to leave the mall, the car felt like it was missing half the cylinders. I could hardly accelerate. It got so bad, that when i pressed the gas, the car almost died on me. Luckily my grandparents house wasnt far. SO i turned off the car, then back on, and she was fine. I have ran out of ideas on what it could be. Some people said it could be the coils, plugs, injectors, or maybe the fuel pump. The plugs are out of the question, and maybe the coils. If any of you have ne ideas on what it could be, please let me know. Cause i have no idea.

 

Does the O2 codes still show up? You could always test the wires with a OHMs meter to see if their still workin

 

the o2 codes havent came up since it first happened. Thats why i dont think that they are the problem, but they still could be

 

I had a similar thing happen to me recently. Flashing ses light, car began to misfire really bad and run like hell, then a solid ses light. Pulled the codes, had a bad o2 and a randomn misfire. Replaced the front 02s (rears are deleted), the codes cleared, and I was back in business. Hope this helps you some.

 

i have to try that out, i just had another code pop up 2night, but havent had a chance to check it, 2marrow between classes i will. Thanks for the info