Full boost, no power..wth?

djkronik57 · Oct 16, 2009

So this morning on the way to work, about a block from home, I turn up a street and accelerate at a normal pace through first (this is a 25mph zone, slightly up hill, and the car is still warming up) and all of a sudden it feels like I have no power, but my boost gauge is registering 16psi. I'm not even at 30% throttle at this point, so I figure something is wrong and let up on the gas, giving a louder than normal *whoosh* through the recirc valve. Confused, I get back on the gas and it accelerates normally and shift into 2nd, and it behaves normally for a few seconds, then it does it again. I'm not even fully back on the gas and I've got 16psi and no power. Again, I let up on the gas and I get a loud *whoosh*. I coast to the end of the street, make a turn, and everything is back to normal.

What the heck was this? I've never had a situation where the boost came on so fast and hard with absolutely no power. By no power, I mean it felt like I wasn't giving it enough gas or in too high a gear and about to stall. Could this be a TCV issue? Or could a dirty MAF cause it?

imageomega · Oct 16, 2009

maybe a hose popped off the tcv?

dave_n_ruth · Oct 16, 2009

Re: (imageomega)

Yeah, something is wrong. I was riding in Short Circuits car when we heard the big Whoosh! He had no boost gage at the time. Depending on the intensity of the sound you should be able to tell if it is a small or big hose. A small hose will just make a PSSssss sound. We found Short Circuits IC hose backed off so that it had just a crack half way around the hose/pipe and it would provide enough air for normal driving, but was opening at WOT.

S60R1 · Oct 16, 2009

Re: (dave_n_ruth)

Report back when you find out what it is http://********************/smile/emthup.gif

George @ ViVA · Oct 16, 2009

Re: Full boost, no power..wth? (djkronik57)

Quote, originally posted by djkronik57 »

What the heck was this? I've never had a situation where the boost came on so fast and hard with absolutely no power. By no power, I mean it felt like I wasn't giving it enough gas or in too high a gear and about to stall. Could this be a TCV issue? Or could a dirty MAF cause it?

Both could cause this issue. I've experienced it when my MAF was on the fritz. Check your hoses, especially the ones to your TCV. Are you running the stock TCV?

phuz · Oct 16, 2009

Where do you have the boost gauge tied in...before the throttle or after it?

lawyR · Oct 16, 2009

Re: (phuz)

I'll second the TCV. Thats more or less what it felt like when the lines to my TCV were reversed.

djkronik57 · Oct 16, 2009

Re: (lawyR)

I have the boost gauge tied in where all the threads and install guides say to, coming out of the right side of the engine. This hose might have popped off (since it was a b*tch to get it hooked up to the T), but then wouldn't my gauge no longer work as well?

I can check the TCV (which is stock), but I haven't touched it in 2 years. I would expect to have some symptoms of a reversed hose before now. Maybe it's just gone bad again? I've been getting normal boost levels and performance until now.

lawyR · Oct 16, 2009

Re: (djkronik57)

May be that the CV hose has come off, or is worn and leaking. It would give the same result....the turbo giving full boost, but no power as the wastegate is letting it all out.

djkronik57 · Oct 16, 2009

Re: (lawyR)

Quote, originally posted by lawyR »

May be that the CV hose has come off, or is worn and leaking. It would give the same result....the turbo giving full boost, but no power as the wastegate is letting it all out.

Hmm, good point, I'll be sure to check the TCV lines as well. But if the waste gate was letting it all out, wouldn't my boost gauge read 0 boost, since there would be no boost getting to the intake manifold? It was at a full 15-16 psi, and even stranger, in 1st gear.

I'm kind of leaning towards MAF, even though I don't want to have to go through ordering the security torx bits.

George @ ViVA · Oct 16, 2009

Re: (djkronik57)

Quote, originally posted by djkronik57 »

Hmm, good point, I'll be sure to check the TCV lines as well. But if the waste gate was letting it all out, wouldn't my boost gauge read 0 boost, since there would be no boost getting to the intake manifold? It was at a full 15-16 psi, and even stranger, in 1st gear.

I'm kind of leaning towards MAF, even though I don't want to have to go through ordering the security torx bits.

If the wastegate never opened, you'd be achieving higher than normal boost. This can be done by disconnecting the wastegate vacuum line (not recommended), or if the TCV internals began to stick and didn't open the wastegate. I'd start with replacing the TCV.

Luckily, you don't need the security torx bit to replace the MAF. You only need that if you want to separate the MAF sensor from the housing. Replacement Volvo MAFs include both, so there's no need to take the MAF apart.

Also, if your MAF is going bad, you may get some CEL codes. When mine died, it died with no advance notice and left me stranded right outside of a Volvo dealer in CT (what luck!)

hoagrod · Oct 16, 2009

Where's Kate B when you need her?

djkronik57 · Oct 16, 2009

Re: (George @ ViVA)

Quote, originally posted by George @ ViVA »

Luckily, you don't need the security torx bit to replace the MAF. You only need that if you want to separate the MAF sensor from the housing. Replacement Volvo MAFs include both, so there's no need to take the MAF apart.

What about to clean the MAF? I'd like to try that first before spending the money replacing it. I guess a new TCV isn't a bad idea as well.

Quote »

Where's Kate B when you need her?

Don't jinx me! She only comes out for hardcore $$$$ issues.

S60R1 · Oct 16, 2009

Re: (djkronik57)

Quote, originally posted by djkronik57 »

I'm kind of leaning towards MAF, even though I don't want to have to go through ordering the security torx bits.

I have a set. And plenty of left over MAF cleaner too, from when I did mine couple of weeks ago.

hoagrod · Oct 16, 2009

It's not a jinx, it's a blessing! She heals all wounds!! 850arrsay where you at?

djkronik57 · Oct 16, 2009

Re: (S60R1)

Quote, originally posted by S60R1 »

I have a set. And plenty of left over MAF cleaner too, from when I did mine couple of weeks ago.

Awesome! Are you going to Swedish car day on Sunday? Was going to skip because of the rain, but I can tough it out.

S60R1 · Oct 16, 2009

Re: (djkronik57)

Quote, originally posted by djkronik57 »

Awesome! Are you going to Swedish car day on Sunday? Was going to skip because of the rain, but I can tough it out.

If I finish my clutch + slave by then, yeah.

But you're welcome to stop by the house anytime this weekend, I'll be there working on the car. I can clean your MAF out in minutes. I'll IM you.

On a separate note, I'm very interested in what you find out. I've been having similar issues for the last 15k miles. My TCVs are burning up every ~5k miles, so I suspect something else is the root cause

so far I've replaced the boost pressure sensor to no avail. PCV system and TCV hoses are next.

Modified by S60R1 at 1:38 PM 10-16-2009

djkronik57 · Oct 16, 2009

Re: (S60R1)

Well since the TCV gets fouled by blow by oil, and I seem to remember you noting excessive oil in your OTE pipe (might be remembering someone else's post though) I'd guess PCV system.

S60R1 · Oct 16, 2009

Re: (djkronik57)

Quote, originally posted by djkronik57 »

Well since the TCV gets fouled by blow by oil, and I seem to remember you noting excessive oil in your OTE pipe (might be remembering someone else's post though) I'd guess PCV system.

Must've been someone else, but I haven't looked in the OTE pipe in many, many miles. I did notice oil residue on the FMIC pipe, when I did the boost pressure sensor, and my car has been losing more oil than usual, so I'm still leaning towards PCV system as well. And after 5 years, 105k miles, new hoses can't hurt either

But this is all best guess. If you find out what the problem is for sure, let me/us know http://********************/smile/emthup.gif

Turbo Country · Oct 17, 2009

Re: Full boost, no power..wth? (djkronik57)

My guess is that your wastegate keeps going out of control, and the ECU notices this, and then takes emergency measures (selectively not firing the ignition?) to cut/kill power in its valiant effort to mitigate the severe overboost condition. But anything like that ought to set a diagnostic err code, right?

Full boost, no power..wth?

djkronik57

imageomega

dave_n_ruth

S60R1

George @ ViVA

phuz

lawyR

djkronik57

lawyR

djkronik57

George @ ViVA

hoagrod

djkronik57

S60R1

hoagrod

djkronik57

S60R1

djkronik57

S60R1

Turbo Country

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