Based on my codes and more obviously by the sound of the engine I am having random misfires. It started after I did a “spirited” start on the highway. It bogged down really bad before the misfires occurred. My first guess was that I need to clean the valves but I did a Seafoam treatment and should’ve at least temporarily fixed the issue. One thing I did before the incident was that I poured hot water on top of my valve cover to clean off some oil and I poured Seafoam into a tank with less than a quarter tank of gas. Any ideas?

 

May try replacing the spark plugs. Then if that doesn’t work. The coils may have moisture or need replacing.

 

The spark plugs are only 500 miles old so your theory with the coils may be the problem

 

1) It really helps if you provide basic info - what year, what model (so we know what engine) and how many miles.

2) you're getting misfires - is that based on just how it is running, or do you have a CEL and have you pulled the codes? Get a code reader (or go to an auto parts store that will read the codes for you) and let us know.

3) assuming you are getting misfire codes specific to one or two cylinders, swap the coils, clear the codes, and see if the misfire codes come back and follow the coils. Then you'll know which coil is the problem.

 

08 r56 turbo with 148,000 miles. Codes appearing are all codes between p0300-p0304. So,all cylinders are effected. Even though the plugs are new I removed them all. They still look new. I bought new coils and they will arrive by Monday. The coils are still the oem that came from the factory when built. Coils were swapped and codes were cleared. Still the same issue. I’m also going to replace the valve cover gasket just because.

 

Misfire is also a sign of weak/about to go HPFP. was it ever replaced?

 

I would find someone who can put a quality scan tool on it, you could have any number of issues that cause misfires across the board; HPFP issues, thermostat electronic fault, timing issue, VANOS solenoid clogged/failed, carbon buildup, vacuum leak, etc. Need more information to go off of.

 

Doubtful that all coils simultaneously went bad. Before you throw more parts at it -
sounds like you're overdue for carbon buildup cleaning, seafoam in the gas won't do jack for that. Could also be the HPFP, check the fuel rail pressure via OBD. What nkfry said.

 

I received my new coils in the mail today and my car is now running perfectly. I’m very Thankful that it only costed $100. The HPFP was in my head but it was going to be my last resort. I also replaced the engine knock sensor because I’ve been having some issues with it for a while. Both were very easy and quick fixes.