So long story short I took the car to GM to resolve a cyl1 warmup misfire, they dropped in a new head under warranty and all seemed well. That was last week, FF to today and the car is seeing 9+ deg of knock, spiking 18lbs and holding 15lbs of boost. It feels like I'm brakeboosting, it kinda tugs but won't fully go. I'm all stock drivetrain wise.

Really don't want to take it back to the dealership as I was stuck in a rental for almost 2 weeks last time. Hoping it's just a hose loose somewhere.

 

My Grand Prix GTP did the exact same thing, turned out to be clogged/melted catalytic converter

-Jamie M.

 

That was a thought. Hoping not because i thunk that warranty expired at 75,000.

Thus was on the last 1/8th of a tank too. Did it the whole way home. Filled her up and parked her last night. Drove like a champ and only saw 5deg on throttle. WTF?

 

I was having this problem too. Term advised me its either stuck WG or leaking BPV.

I found out it was a boost leak on my lower CP at my TMAP sensor. Getting the new sensor today and I'll let you know the outcome. first thought is to check for boost leak as my WG looked good, and i have the forge BPV

 

A boost leak would cause high boost at the manifold? Running an analog boost gauge.

 

EPA requires that they are by MFR for 6 years from what a friend of mine told me last year when they go theirs replaced. Might be worth asking about as they should be on the shelf or a couple of days from the part warehouse.

 

Forgot to mention, car drive fine and pulled hard today. Sometimes i really hate this car