gathermewool
Site Donor 2023
Car: 2014 Subaru Forester XT
Miles:~34k miles
What: Tapping knocking sound upon initiation of boost, engine falls flat on its face (no power.) Then, nothing...
Fuel: 1/4 tank (110 miles left indicated)
Oil: just above full mark (no consumption in the past 7,300 miles of this OCI
CEL: None
Boost: Not noted at the time (boosted fine afterward)
RPM: seemed unusually low when the incident occurred.
I've had my ECM updated in the past for a hard/long-start issue (it would crank for 5+ second before starting and sometimes even crank until it timed out.) The reflash fixed this issue.
I've more recently had my ECM updated for the low-speed knock that I never experienced (I actually received a letter from Subaru for this one.) Well, that is until today...
We drove the car 15 minutes to check out some replacement exterior doors without any issue, at 35-50 MPH the entire way (oil temperature reached 180F+. When we left, there was a little bit of traffic, but not much. To ensure I didn't slow anyone down I got onto the road and gave it maybe 30-50% throttle (this engine typically revs to 2.5k RPM+ with little to no boost and then ramps down to lower RPM and higher boost)
Not this time: As soon as I accelerated I heard the loud :TAP-TAP-TAP-TAP-TAP: and felt the engine fall flat on its face. I let off the gas and looked down simultaneously, and noted that the engine speed was below 2k RPM, unusually low for 30+% throttle. I didn't note boost level.
This vehicle has multiple drive modes, with I (intelligent) being the tamest (lowest throttle response and boost level) and S (sport) mode being a little more responsive. I typically drive in S-mode, only because it starts out a couple of hundred RPM higher at all times than I-mode, so it's more responsive to tip-in. When I switched from I mode to S-mode, everything was normal. I switched back about halfway home and everything was again normal.
The turbo in this engine is twin-scroll, so it boosts very quickly and easily - I didn't intentionally boost on the way home, but it did so all by itself, without falling on its face like previously mentioned.
I've already left a message with the dealer to setup an appointment, but what do you guys think? Flame suit is already on for not pulling over immediately and checking the oil.
Miles:~34k miles
What: Tapping knocking sound upon initiation of boost, engine falls flat on its face (no power.) Then, nothing...
Fuel: 1/4 tank (110 miles left indicated)
Oil: just above full mark (no consumption in the past 7,300 miles of this OCI
CEL: None
Boost: Not noted at the time (boosted fine afterward)
RPM: seemed unusually low when the incident occurred.
I've had my ECM updated in the past for a hard/long-start issue (it would crank for 5+ second before starting and sometimes even crank until it timed out.) The reflash fixed this issue.
I've more recently had my ECM updated for the low-speed knock that I never experienced (I actually received a letter from Subaru for this one.) Well, that is until today...
We drove the car 15 minutes to check out some replacement exterior doors without any issue, at 35-50 MPH the entire way (oil temperature reached 180F+. When we left, there was a little bit of traffic, but not much. To ensure I didn't slow anyone down I got onto the road and gave it maybe 30-50% throttle (this engine typically revs to 2.5k RPM+ with little to no boost and then ramps down to lower RPM and higher boost)
Not this time: As soon as I accelerated I heard the loud :TAP-TAP-TAP-TAP-TAP: and felt the engine fall flat on its face. I let off the gas and looked down simultaneously, and noted that the engine speed was below 2k RPM, unusually low for 30+% throttle. I didn't note boost level.
This vehicle has multiple drive modes, with I (intelligent) being the tamest (lowest throttle response and boost level) and S (sport) mode being a little more responsive. I typically drive in S-mode, only because it starts out a couple of hundred RPM higher at all times than I-mode, so it's more responsive to tip-in. When I switched from I mode to S-mode, everything was normal. I switched back about halfway home and everything was again normal.
The turbo in this engine is twin-scroll, so it boosts very quickly and easily - I didn't intentionally boost on the way home, but it did so all by itself, without falling on its face like previously mentioned.
I've already left a message with the dealer to setup an appointment, but what do you guys think? Flame suit is already on for not pulling over immediately and checking the oil.