Recovering Lost Power

[WhatAmIDoing]

I’ve had this work before:

Shift into one of the lower gears at the bottom of the shift selector plate, get it up to 4K rpms more or less continuously for several minutes on a stretch of state highway. Repeat that multiple times in the same outing.

If what I’ve read is true there is a TSB out there that is basically a more extreme version of this where you just drive at high rpm for like 10-20 minutes straight. Idea is to clean intake valves for better sealing.

I can’t personally bring myself to keep the rpms up ten minutes straight so that’s my watered down version.

Did that today. Will see if things change. Compression test seemed to indicated that valves aren't stuck.

Just had a thought, maybe fuel pressure isn't high enough to support high load?

[June]

I’ve had this work before:

Shift into one of the lower gears at the bottom of the shift selector plate, get it up to 4K rpms more or less continuously for several minutes on a stretch of state highway. Repeat that multiple times in the same outing.

If what I’ve read is true there is a TSB out there that is basically a more extreme version of this where you just drive at high rpm for like 10-20 minutes straight. Idea is to clean intake valves for better sealing.

I can’t personally bring myself to keep the rpms up ten minutes straight so that’s my watered down version.

Did that today. Will see if things change. Compression test seemed to indicated that valves aren't stuck.

Just had a thought, maybe fuel pressure isn't high enough to support high load?

Lack of fuel would cause pinging? June

[WhatAmIDoing]

I’ve had this work before:

Shift into one of the lower gears at the bottom of the shift selector plate, get it up to 4K rpms more or less continuously for several minutes on a stretch of state highway. Repeat that multiple times in the same outing.

If what I’ve read is true there is a TSB out there that is basically a more extreme version of this where you just drive at high rpm for like 10-20 minutes straight. Idea is to clean intake valves for better sealing.

I can’t personally bring myself to keep the rpms up ten minutes straight so that’s my watered down version.

Did that today. Will see if things change. Compression test seemed to indicated that valves aren't stuck.

Just had a thought, maybe fuel pressure isn't high enough to support high load?

Lack of fuel would cause pinging? June

Then maybe not that. I just don't get it. It's a beast the rest of the time, but once she hits an uphill grade it's like I'm hauling a 25 tonne trailer.

[SuperHerman]

Were it me and I had a lack of power and an over boost situation I would focus on the turbo, its plumbing and boost solenoid like FLXC90 suggests.

Just went through this on my XC90 - it was a compromised hose. What codes are you getting?

[June]

Perhaps the TCV is failing? June

[WhatAmIDoing]

I'll inspect and try to smoke all the vacuum lines and hoses again tomorrow. Wish I had a known good TCV to test, but find it weird that it would boost fine on a flat but not uphill. I have codes for the evap system and for an unplugged downstream O2 sensor.

I just feel like even without the help of a turbo, it should hold more speed uphill than this. I would think an S70 NA could maintain 55mph on a 1 mile 6% grade, meanwhile I can barely do 45 before I hit the summit, and i was doing 80 at full throttle when I started the incline.

[mecheng]

Squirt some WD-40 in your TCV, it could be getting lazy, but if you can change it. Check all your vacuum lines, they tend to degrade with time. Make sure you are using 89 octane minimum, you could be getting detonation and the car is adjusting the timing on the grades. Lastly, complete the tune up with air filter, fuel filter, and cap and rotor. If all else fails, adjust your waste gate actuator, but only a fine tune adjustment.

[jtp]

Have you done a leakdown test since this issue started?

I've read ring wear problems can show up when driving uphill before they show up elsewhere.

I believe this is because there is more positive crank pressure to begin with on an uphill climb relative to flat pavement, so when you punch the gas while going uphill it's harder for worn rings to seal than when you punch it on a flat stretch.

[WhatAmIDoing]

Have you done a leakdown test since this issue started?

I've read ring wear problems can show up when driving uphill before they show up elsewhere.

I believe this is because there is more positive crank pressure to begin with on an uphill climb relative to flat pavement, so when you punch the gas while going uphill it's harder for worn rings to seal than when you punch it on a flat stretch.

Did a leak down test, 1,3,4,5 passed with flying colors. I couldn't get a good seal on #2 due to the plug coming out cross threaded.

Squirt some WD-40 in your TCV, it could be getting lazy, but if you can change it. Check all your vacuum lines, they tend to degrade with time. Make sure you are using 89 octane minimum, you could be getting detonation and the car is adjusting the timing on the grades. Lastly, complete the tune up with air filter, fuel filter, and cap and rotor. If all else fails, adjust your waste gate actuator, but only a fine tune adjustment.

WD-40 into the TCV, is that safe? Or would silicon be better? TCV lines are in good shape. Running 93 octane. Air filter is brand new. Fuel filter and cap & rotor are only a year old. Inspecting the wastegate today.