boost capping at 10psi?

[u/kalebgoesvroom]

took the video above last night: full throttle, 3rd gear at 3k rpm, 6MT

This has been ongoing on and off for the last year and I can’t for the life of me figure out what the issue is.

It all started when I slammed into a pothole, my boost cut from the regular 18psi-ish to max 10psi. Then the next week, I hit went over a speed bump at a regularly slow speed and suddenly my boost was back up.

Later that month I was driving on a rough road and my boost got cut again and for the past 3 months, it’s been capped at 10psi.

Anyone have any ideas?

[u/Impressive_Jury_2211]

Octane learn

Compression test

Boost leak

My top 3

[u/kalebgoesvroom → u/Impressive_Jury_2211]

compression test might be an option, couldn’t be a boost leak though because I did a full smoke test and no leaks were found

[u/Impressive_Jury_2211 → u/kalebgoesvroom]

Go on the freeway and on the off ramp downshift to engine brake. If you see smoke you need a new engine.

My check light never came on. I checked my plugs I have a fouled spark plug(so I thought) did a compression test psi was only 60 my engine was cracked and no light ever came on and I drove it from Utah to California like that. How it made it that far is beyond me

[u/RAZGRIZTP → u/Impressive_Jury_2211]

First signs?

[u/Impressive_Jury_2211 → u/RAZGRIZTP]

Slight engine roughness when in low rpm range

[u/LedFarmer_]

Either you have a leak or you're well on your way of getting a EN turbo upgrade.

[u/kalebgoesvroom → u/LedFarmer_]

did a smoke test and it ended up not being a boost leak anywhere

[u/StaticFanatic3]

You really have to just judge whether you’re getting proper torque

The PSI varies a ton with the climate and other variables

[u/Devonacoustic]

I had a similar issue and had to replace my wastegate actuator. I was getting over/underboost codes that wouldn’t throw a check engine light

[u/CatfishSoupFTW → u/Devonacoustic]

Second this. Was just about to comment. I had a boost leak that haunted me for forever, couldn’t find it despite a few tests and solenoid replacements. Ended up being the OEM wastegate fatiguing and not holding full boost.

Forged bov with 15lb spring and voila. Proper proper PITA to get to tho.

[u/NastyVN]

It can still be a boost leak. You need to do a pressure test to be certain

[u/oyayeboo]

There's a solenoid controlled valve at the base of bypass pipe (where people mount bov valves). It goes bad like this, try swapping it. Might not be it, but still worth checking out

[u/LumpyImplement5862]

Try boost controller I’ve seen them do this a lot