Gibby550

Been having a rough idle lately and this morning had a real bad misfire followed by the cel. Had autozone check it at lunch and had 11 codes pop up. P301-308. Changed the plugs last xmas so was hoping it was just a coil. But all 8 cylinders? 06 550 with 98000 miles. Couple of weeks back added fuel system cleaner to help with the rough idle, possible that the injectors need cleaning. Probaly need to get the codes cleared and start fresh, what do you guys think?

pcy

Yes, go ahead and clear the codes and see if they come back.
If they come back, yo uwill need to look at parts that correspond to all cylinders.
Disconnect MAF while engine is running. When you disconnect, if there is no difference in how the engine runs, then you will need to clean/replace MAF.

Gibby550

PCY- Thanks for the insight, I cleaned the MAF when I first had the rough idle. I'll disconnect and see what happens. Should I expect the RPM's to drop when I disconnect?

pcy

If MAF is working properly and if you disconnect MAF while engine is running, you will definitely notice erratic engine performance because the air going in to intake is not being measured and ECU doesn't really know correct amount of air going in to the engine for proper mixture of fuel.

If you see no difference when you disconnect MAF, then I am confident the MAF is malfunctioning.