Monday, December 28th, 2009 AT 7:37 AM
I drive for a corporate car service company (luxury sedan transportation). About 2 weeks ago I was waiting in front of a pick up waiting for my passenger and my cars idle shot from 500 rpms to 750 rpms and it was shaking as if one of the cylinders wasn't firing. The check engine light also went on. I took it to one mechanic he told me that the cylinder 5 ignition coil was no good. I had watched the codes on his diagnostic computer and I noticed 2 codes. One was for the misfire in the number 5 cylinder, and the other was for "system running too lean bank 2". I changed the ignition coil and went on my way. The idle still wasn't normal and I still felt the shaking a bit. I went on my way and a few hours later the light came back on and the shaking came back. I went to another mechanic he said it was the number 5 cylinder ignition.I explained I just changed that. He then told me that the spark plug was probably bad and caused the second (new) ignition coil to go bad again. I watched him as well when he pulled up the codes on his diagnostic computer and he only got the code for the misfire in the number 5 cylinder, no code for running lean. Now I changed all 8 spark plugs and the number 5 coil again. And I went on my way. 1 day later. Same problem and I got the check engine light again. So now here I am 2 ignition coils later with brand new plugs and I still have the same shaking. I went to a 3rd mechanic. He plugged in his handy dandy computer to the obd port and pulled up the code on the computer saying that the system is running lean bank 2, and the misfire in cylinder 5. He insisted on changing the plug and the ignition coil and taking it from there. I tried it one last time with the same results. Now.I have a suspicion that it might be the number 5 cylinder injector thats bad, is that a possibility? The car normaly idled before this whole thing started at 500 rpms FLAT! Now when the car is running its smoothest its just above 500 rpms. The cars idle is relatively smooth when I run the car for a while. The problem starts when I idle for about 15-20 mins then the shaking starts. Its as if after some time idling it just starts misfiring. The idle never goes the original 500 rpms, but it doesn't always shake either. It idles sometimes just above 500 when its smooth, and just below 750 when its misfiring. I also don't have the same power when I'm on the highway, feels like I'm running on 7 cylinders rather than 8 and I know this because at around 2000 rpms on the highway this car had effortless pick-up, and now I don't feel that power even well above 2000 rpms. PLEASE HELP. Its driving me insane. What are the problems I'm looking at?