The "misfire" problem is back! I took it to the dealer about 3 months ago and they diagnosed the problem as the right bank MAF sensor. So I replaced it. Iam gonna swap the right side and left side units and see if that fixes the problem. While Iam at it Iam gonna replace all the vaccum lines running on top of the engine. Here are all the error codes Iam getting from the autozone generic OBDII scanner.
P1146
P1148
P110
P300
P309
P312
P307
The same codes as I was getting before. The dealer told me that the vehicle wasnt misfiring but instead the idle was going up and down. When Iam at a stoplight and it happens the car lurches forward a bit. Maybe throttle body? Iam suspecting air (vaccum leak). The problem seems to have started when I changed out the Charcoal activated cabin filter (One that needs to be changed frequently, not the big one) The check engine light comes on even after code is cleared, but car still hawls ass! Iam grateful for any suggestions. -Thanks again!
Vehicle year 1998
mileage 66,000
Merc s600 LWB
Spark Plugs changed out (less than thousand miles)!
air filters replaced (less than thousand miles)!
Definitely check all vacuum lines. My S600 had a couple loose-fitting hoses that would come off from time to time, and it would cause idle problems. I replaced all the hoses I could get to. The MAF (called Air Mass Meter by MB), or the wiring to it, is also a likely suspect. My AMM's wires were shorting out to each other due to the infamous insulation problem. But since you have a 98 model year, that is probably not your problem.
I put my old right bank sensor on the left side and check engine light went away. Iam thiking the dealer told me the wrong side. Will drive for a couple miles and see.
Have a very good look over all the intake plumbing, too. Make sure there are no tears in the rubber elbows between the MAF sensors and the throttle bodies. Someone posted a pic of one he replaced, that had a big tear in it. I would probably be best to completely remove them to inspect them. Not too difficult to do. Mine have significant cracking on the outside surface which worries me a little that some cracks might go all the way through, but I haven't had a good reason, yet, to give them a good looking at.
Keep this in mind too, the MAF on the left side of the engine controls the right bank, and vice versa. This could be confusing to someone not familiar with V12's. And as Brett says, the rubber intake runners do crack with age. I had to replace one of mine because of a large crack.
Thank's for the help guys! I drove the car last night and it ran like it should. Iam gonna do another inspection of the engine to make sure everything is ok. I was very suprised to find out how brittle the vacuum lines over the engine bay have become over time. One pipe broke into five pieces while I was handling it. I ran some easily removable plastic shroud tubing over the lines to minimize the damage from heat. It is really becoming hard to find a competent mechanic to work on this vehicle hence I must teach myself more. My biggest question is why did the code reader at autozone give me all those fault codes while the dealer got the code right away that it was the MAF sensor?
So exactly what was the code that the dealer said was the MAF sensor? I could be wrong, but the dealer mechanic very likely saw the same codes you saw, looked up the codes in their service information, and spouted off to you the first thing the book says to look at. OBD II DTC's (diagnostic trouble codes) often do not tell you exactly what part is faulty. They provide data that should be used to guide the diagnostic process. Many times, fault codes pertaining to one part are caused by failure of another part. But, I see from your codes listed that you have 2 codes (P1146 and P1148) that are Mercedes specific codes (not generic OBD II codes). I don't know what they mean. You'd have to have inside information to find out what these codes mean for Mercedes cars. Maybe someone here knows. OBD II codes whose numeric portion begins with a 1 are manufacturer specific.
s600 Error Codes 
Linear Mode
