tderrick

Hey tderrick, I have a 99 es300 and had the exact same situation. Hear me out on this. I also had misfires on almost all cylinders, check engine light was on, almost every mechanic I went to told me I need a tune up or coils or plugs changed or catalyst converter changed etc etc. I was so frustrated because I could not find from anybody what the exact problem was. But to my surprise, the problem was the oxygen sensors. I replaced all three of my oxygen sensors and the car was good and still is good. But you will not need to change all three sensors. It probably is one of them. You will need to go to a mechanic and tell him to perform the diagnostic to find out which sensor needs to be changed. I found out that I needed to replace my oxygen sensors by an electronically modulated diagnostic which checks the car performance in frequency and waves. This was performed by a highly professional technician. I would suggest to get this done and you should be good. Also by the way, before my problem was resolved, my car ate gas like it was free. Unfortunately, this morning I authorized the work to be done, limited to new plugs and coils. Hopefully, this tune-up will do the trick. But after reading your comment about eating gas, I am not so sure now that the plugs and coils needed to be replaced. If when I pick up the car this afternoon, I find that the car still runs crummy, who should I go to for the electronically modulated diagnostic, since I dont believe this mechanic can do this type of diagnostic. He uses the basic ODB plug in port type kit for testing. You should go to any certified mechanic shop. But remember to tell them that you are having misfires and that your plugs and coils are fine(you had them changed). Tell them does the problem have to do anything with the oxygen sensors. Mention to them that someone else had this problem too and the problem was the oxygen sensors. I also had a tough time finding a mechanic that could diagnose this problem, and luckily there was only one which found the problem and fixed it in like 15-20mins. About the test, the mechanic did the test while the car was running and while the car was idle. He was checking frequency waves, and other measures which I am not exactly sure of. He had the wires connected to the battery and the under the steering wheel you check the OBD codes from. If you are located in NY, which I doubt, I can give you the address. But I am 99.9% sure it is your oxygen sensors. If anything, just let me know and I'll see how I can further help you. Well, this past Friday I picked up the car and after three days, its running better than it has in years. The only work that was done was the tune-up (6 new double platinum plugs). I guess that the oxygen sensors were'n't it at all. Thanks for your time and thoughts. PS> Im in Southern California where oxygen is at a premium!

Hey tderrick, I have a 99 es300 and had the exact same situation. Hear me out on this. I also had misfires on almost all cylinders, check engine light was on, almost every mechanic I went to told me I need a tune up or coils or plugs changed or catalyst converter changed etc etc. I was so frustrated because I could not find from anybody what the exact problem was. But to my surprise, the problem was the oxygen sensors. I replaced all three of my oxygen sensors and the car was good and still is good. But you will not need to change all three sensors. It probably is one of them. You will need to go to a mechanic and tell him to perform the diagnostic to find out which sensor needs to be changed. I found out that I needed to replace my oxygen sensors by an electronically modulated diagnostic which checks the car performance in frequency and waves. This was performed by a highly professional technician. I would suggest to get this done and you should be good. Also by the way, before my problem was resolved, my car ate gas like it was free. Unfortunately, this morning I authorized the work to be done, limited to new plugs and coils. Hopefully, this tune-up will do the trick. But after reading your comment about eating gas, I am not so sure now that the plugs and coils needed to be replaced. If when I pick up the car this afternoon, I find that the car still runs crummy, who should I go to for the electronically modulated diagnostic, since I dont believe this mechanic can do this type of diagnostic. He uses the basic ODB plug in port type kit for testing.

you are correct, no wires, just a coil. the plugs are platinum. so, perhaps I was misled to believe they would last longer. also, found the old repair invoice and coils were not replaced at the 1250000. Maybe the simple tune-up including new coils will do the trick. I hope so. Others on this thread have not been so lucky at times.

Check engine light on, diagnostic indicates 4 separate misfire codes on cylinders 2, 3, 4, and 6. Car has 180000 miles on it. Had 6 new plugs and coils/wires installed at 125000. Assumed that plugs would last up to 100000, but mechanic is suggesting a tuneup replace and remove all 6 including coils/wires. Will this guarantee that the car will run smoothly again?