Z's Z-28

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.

98 camaro

man that sucks.....a couple of people ( including me ) have been having some low rpm idling probs but nothing that harsh. Ive checked my plugs,wires,coils,and o2's....and i still have a prob, although im not throwing any codes, it does feel similar to a random cyl. misfire. I cant figure it out. Good luck with yours and if you find the prob please let us know.....good luck

my01camaroz28

iTrader: (15)

A flashing SES light usually means multiple misfires. I bet there is either a wiring short associated with your fuel/02 sensors or the sensors are bad. I have an 01 Z28 modded and took it up for tuning in December. I drove a head/cam/dual exhaust car for four hours getting crap for gas mileage. The car would run on the highway but would spit, choke, stall the whole way intermittently. WHen I got the car there the driver's side 02 was shot. It tripped out the entire system for air/fuel. My SES light was talking to me the whole way. Hope this helps.

Aegnor

Double check your cats/O2's as well. When a cat gets clogged up it can back the exhaust gasses up in the headers, cylinders, and heads, which will cause a massive power loss, if not outright engine stalling until the gasses can work their way past the blockage. I never had it happen on my Z, but when I had a 94 V6 (3.4L) my cat got clogged up, and I was lucky to be able to limp the car to a shop about half a mile away. The clog was apparently due to the engine not firing on a cylinder or three every now and then, and just dumping unburned fuel into the exhaust, which really gummed up the cat matrix.

ArKay99

iTrader: (1)

I recently had misfiring. It came down to air leaks behind the MAF. You might want to check all the fittings behind the MAF. Check the throttlebody is not loose. I also checked my intake manifold and it was loose. Not flopping around but more than half the bolts were only a little tighter than finger tight.

Something is changing between starts. It might be the O2's, but how hard is it to check your air path for leaks. Lastly, have you done any work to the car recently. I always go back and check myself if I have a problem that develops shortly after a mod or some work. I'm usually to blame.

Z's Z-28

good idea on the maf, i might have to check for air leaks and check to see if a cat is clogged. The only work i have done is change out the spark plugs, except for putting a cat back system on it. Im having a mechanic look at it this thursday. Hopefully he will come up with and answer

Z's Z-28

i took it to a mechanic, he was a personal friend, he put the snap on readers and read that cylinder 1 was misfiring over 9,000 times, he ran some b and g injector cleaner through the fuel rail. So far so good

Viper

iTrader: (6)

Another thought if it comes back. Pull the valve covers and make sure no springs are broken, bent pushrods or loose rocker arms. A broken valve spring will of course usually make nosie, but also cause huge misfires and a flashing SES.