97 e420 Missfires no power gas smell - PeachParts Mercedes-Benz Forum

mmcfearin · #1 01-07-2013, 11:05 AM

This has been a long problem I have been working on, it started around 160K I had a long road trip to Ohio and back to VA for X-Mass last year. The car did wonderful until 20 miles from home. The car started misfiring and I got an error on the dash of electrical problem. I pulled over checked all the fluids restarted and all was well. Got home with no problems. A week later I was headed down the road but when I got to a hill it felt like I was losing power fast and then got the electrical warning as well as rear brake sensor, (I know I do need a break job on rear). At home the car idled fine but had the smell of raw gas from exhaust.
Had my indy look at it as I normally do my own work but I didn't have an OBD scanner at the time. It showed bad O2 sensor and multiple misfires. I went ahead as I was at 160K now and had all plugs replaced, boots, all 4 O2 sensors (with Bosh) and fluids changed. Did not replace ignition coils. After this car ran beautiful again for about 6k.
At around 6k later got electrical problem warning and sometimes felt misfire. I bought a scanner and checked and reported Right front O2 sensor and misfire on 2,3,8. The gas smell was back as well. This was the start of my long repairs.
First I replaced Boots on 2,3,8 --- no change
Replaced all plugs - (indy had used platinum, I replaced with non platinum)
Also replaced ignition coils on 2,3,8
Car is even worst now reporting multiple misfires, O2 sensor, Misfires on 2,3,8,5 and when I try to drive it the car has no power, idles well but once I start driving and get to 25MPH everything goes to hell and the misfires start and I can’t go any faster even at high rpm. It actually now feels like the trany is in the safe/get home mode.
Any ideas? What do I test next, I have not replaced the O2 sensor just because I can't see one sensor doing all this. Some one suggested a fuel pressure or supply issue but I don't know how to test this or what to replace next.