2002 SS, longtube headers, magnaflow catback
So pretty much the exact same thing has happened to me 3 years in a row after I have brought my car out of winter storage. I take it out for its first burn and I take it easy and it runs great for like the first half hour. Then it starts to have a rough idle and if I take it out on the highway it spits and spudders and the engine light will start to flash. Code is saying misfire on cylinder 6, last year when this happened it was a multiple cylinder misfire but it produced the same results. I replaced my front o2 sensors and it worked great for the rest of the summer so im pretty darn sure that is the issue again. So my question is what brand of sensor do I need to use for this to stop happening and what happens to them over the winter when they are just sitting there. Its starting to really annoy me.

 

The problem you described and the fix you did do not match up. If the O2 sensor was bad it would cause a fuel issue across all cylinders. Long before you would get a miss you would get a O2 sensor out of range code. The computer knows the range the O2 sensor should operate. I have yet to see, hear or even read about a car that had an O2 sensor cause a miss. In most cases it is the opposite the miss causes the O2 sensor to go bad.

I could go out to my car and cut the O2 sensor and I would not get a miss until I fuel fouled my plugs in 3-4 thousand miles. At that point the only way to fix it would be to replace the plugs and the O2 sensor.

 

sounds like a weak plug or plug wire, maybe coil. weak spark would require optimum fuel mix to work without throwing a code. replacing 02 may have given you the right mix. also could be coincidence and moisture is in your cam/crank sensor, coil, wire harness, etc, and is burned off when engine is warmed and cooled a few times.

 

I agree, but it could be a wire getting bumped. If the O2 sensor is the cause the miss would be a lean miss and looking at the plug would show them white. Lean requires more power from the coil. For it to be so bad that it effected idle then driivning would be really bad. More likely would be the Bad O2 sensor is a result of the issue not the cause.

I had a customer one time that was sure he was going thru distributer caps. He put on 3 in 6 months. Everytime he replaced them the car would start running better. He had a bad lead going to the coil. You could wiggle it and it made the motor run better.

 

Last year you had multiple misfires, now you are getting a single cylinder misfire. Except for misfire these are entirely different problems. Multiple random misfires means that at random times random cylinders misfire. This is usually due to something that affects all cylinders, usually an ignition component associated with all cylinders or a lean fuel condition affecting all cylinders. What you now getting is a single cylinder misfire, which is usually due to an ignition or fuel problem with components dedicated to the misfiring cylinder. Spark plug fouled, improperly gapped, wrong plug for the engine, ignition wire, ignition coil, coil control lead, bad fuel injector, mechanical problem causing excessively low compression on that cylinder. As Gorn said, a bad O2 sensor would not affect just a single cylinder.

 

it might help to know what processes and products are being used wehn preparing it for storage.

Any additives, is the car stored with a full fuel tank?

Where is it stored?

 

Okay guys I think it was a false alarm. I took a second look and the plug wire seemed to be loose, snapped it on and it seems to be alright. Might have to get a new set of wires, and it sucks to get into there but at least its not cylinder 8. So thanks for the reply everyone. And Gorn what you said does make sense but as soon as I changed the sensors last year the multiple misfire stopped, the dealer told me the sensors would cause that to happen but who really knows. At that time I was getting the random misfire code and the front o2 sensor code. Maybe I have an issue somewhere else causing this but I will see what happens because this issue was different.
And I store my car inside, not heated. Always fill the tank and add some stabilizer.

 

having a lose spark like that is hard on the everything, coil, plug wire and spark plug. yep plug wires need replaced every few years. i have a 10 year rule. if they are still around after that long its time to replace. usually at about 5 years they start failing.

 

Remember, if you ever drop an O2 sensor during the process of installation, it is considered damaged and you should replace it. I would look into Denso O2s.

How old/how many miles on your plugs and wires?

Also spray MAF cleaner on your MAF wire area, if you have an oiled air filter, some oil can sometimes transfer to the MAF wire leading to imprecise readings -dust/dirt can also cause this. You want these clean at all times regardless.

 

Ya I think I will replace all plugs and wires this year. I have no idea if they are originals or not. Bought the car with 58000kms and now have 68000kms so I should just do it. And I do have a K&N filter so cleaning my MAF is a good idea to.