HELP...Low Boost/Power 6.8 psi max...what could be wrong?

[E46MysticM3]

Hello everyone, I am having very frustrating low boost/power issues. I measured using an app that shows live data via OBD 6.PSI max boost achieved. And it feels it. Whats weird is every few days, the boost will come back to what feels like how the M5 should feel. Then will go away the next day.

Here is what I have already tried:

1) Checked Vacuum lines at mufflers
2) Original Chargepipe was leaking, replaced with new upgraded one and no difference
3) Replaced torn intake boot, no difference
4) Replaced both sides crankcase hoses that were leaking, no difference.
5) Checked vacuum line by the driver side airbox and it is solid.
6) Cleaned MAF with CRC Cleaner

Don't know where else to look. Any help appreciated!!

[M5Rick]

209k miles okay, all stock I presume. Both MAF's CRC spray cleaned? at those miles it may be beneficial to replace them if not done so already and nothing is blocking the stock air box intakes at the bottom or has been sucked up to the air filters.
I'd be removing all that and checking.

[E46MysticM3]

Originally Posted by M5Rick

209k miles okay, all stock I presume. Both MAF's CRC spray cleaned? at those miles it may be beneficial to replace them if not done so already and nothing is blocking the stock air box intakes at the bottom or has been sucked up to the air filters.
I'd be removing all that and checking.

I actually did this too, I totally forgot. Cleaned with CRC MAF Cleaner. And yes, 209k miles lol.

[M5Rick]

Could be spark plugs crying enough at higher revs, a coil that's nearing its end or simply tired turbos that need reconditioning.. I gather the turbo coolant pump is working fine and the little reservoir is topped up.

[E46MysticM3]

Okay…so this is getting strange now. I unplugged the battery for 30 seconds to reset itself. Car just logged nearly 17psi and pulls like a freight train. I wonder if this is software??

[E46MysticM3]

Originally Posted by M5Rick

Could be spark plugs crying enough at higher revs, a coil that's nearing its end or simply tired turbos that need reconditioning.. I gather the turbo coolant pump is working fine and the little reservoir is topped up.

Reservoir level is good, how do i know the turbo coolant pump is good?

[E46MysticM3]

I have the following ghost codes. No lights on dash or idrive.

[M5_Raz]

O2 sensors are easy to change, I’d try those if you don’t want to bring it in to a shop yet.

[E46MysticM3]

Originally Posted by M5_Raz

O2 sensors are easy to change, I’d try those if you don’t want to bring it in to a shop yet.

Can you tell which o2 sensor it is? I know each bank has 2 o2 sensors

[M5_Raz]

I can’t, but like I said they’re easy to change out. All 4 aren’t too bad. Maybe start with the top two?

If you need a guide you should watch YouTube videos on how to install catless downpipes. Removal of o2 sensors is one of the steps.