I have one more for you guys. My 97' 850 R Wagon seems to be lagging a bit when the turbocharger engages. This is my first Volvo, and my first turbo charged car but I thought it would push a little harder towards the higher RPMs. In other words, when the turbo kicks in, it kicks pretty hard but then seems to ease off too soon. Is there any test I can do to make sure I have a properly working turbocharger and or fuel delivery system? Does anyone else have any experiences like this one?

Thanks,
Chet

 

If your having turbo lag and fade, then I would consider replacing the CBV, it may be old and worn. IPD just came out with one. I would also check for vac leaks.

 

Connect an aftermarket gauge and see exactly how much boost it is pushing.
The 15G is very common to boost fade.

 

If that is the problem then what is the solution. Do I need a new turbo at some point? what would you recommend? I am ok with replacing with non stock parts if it wont effect the reliability too much.


Thanks,
Chet

 

Lots of people replace parts with non stock parts, that's how you mod a car. Adding an aftermarket boost gauge is pretty common, since the stock boost gauge is pretty useless. If 15Gs are prone to boost fade, that means that yours is fine. Now if it's horrible boost fade, then may need a new turbo, but you won't know that until you know how much your boosting and what it's dropping off to.

 

What is a 'CBV'?

Something I have noticed in many threads is the use of acronyms. I think as a general service to all users of the forum, be it new guys or old that we spell out the acronyms for all those reading. I am embarassed to ask the question but I really cant figure it out. 'control boost valve'?

 

Sorry. Compressor bypass valve. It's the rubber "flange" and spring on the turbo that opens and closes the wastegate, essentially allowing you to create boost, and if it's old, causing boost fade.

 

IPD's HD CBV

 

Actually, post *****, it does not allow do anything to the wastegate. All it does is when you let off the gas, the turbo piping has all this metered air that it needs to recirculate, so it goes back right before the turbo. The the intake manifold now has a vacuum since you let off the gas, and this negative pressure has let open the CBV, alowing the pressurized air in the turbo piping to get recircluated.

 

jesus, sorry, I'll try to make sure not to make anymore mistakes.

Well regardless, it says right in the description delayed boost, if he's having boost lag, then this might be fix.

 

I was just making fun of yourself because you called yourself a post ***** in another thread.

:P

No worries, I don't even know what I thought a CBV was when I was looking it up.

The delayed boost would be because some of the air is seeping though the CBV back in front of the turbo, but after the MAF. This can be caused by a rip, or a weak spring.

Edit:Trying to find the post of the post ***** part...

Double Edit:

FouND IT!

 

Bah hahaha. I forgot about that. Sorry for the response. I'm little snappy because I'm at work right now and my boss didn't show up, and another person decided not to come in without mentioning it to any of us, and it's the busiest day of the week, and it's been non stop since six this morning and I've been up since five, and there's still a lot to do and it's raining out so there aren't even any hot girls walking around campus right now for me to look at and feel better and it's just been a rough morning and I'm on my 9th cup of coffee.


I think he should hook up a boost gauge to see if he really has an issue at the moment or that the car is acting completely normal and he's just not used to it.

edit: And I am a post *****. So what of it?!?!?!?!

 

You may be right, it may just be normal. I will hook up a secondary boost gauge and see what it reads. What kind of numbers should I be looking for at what RPM? And I appreciate your post whoring, it has helped me out here and many times in the past.

Thanks,
Chet

 

You should be hitting around 11-ish PSI, maybe a spike to 12 or 13. I'm not exactly sure what the PSI/RPM's are, but it should like something like that. Maybe a drop off to 10 PSI at higher RPM's, like I said, that's just me guessing that's what it would look like.

 

If you have the the normal urbo model you should hit around 9.6psi, or around 10. It will spike up to 15 or a litte below when it shifts, but this is normal. Make sure wen you test you do t at a safe place that you can go straight and watch your boost guage.

 

But he has an R, so boost should be a little more than 10 PSI.

 

Is it just me or are you guys forgetting he has an R?

I thought the ECU is setup in the R and T5-R to only have the max hp (240hp) only for ~20seconds when you floor the pedal, then it drops back down to what 220ish????

And the 15G does drop out in the higher rpms, just not as bad as my little 13C, which is ~5000rpm.

 

Oh yeah, oops. I believe that the R-ECU goes for 10.5-PSI, for 20 seconds like TIPSP said.

 

But not always my R was only boosting 7 PSI all day when I got it. The Boost rating is only a guess!!!
All cars are different.

 

Thanks guys, this info is helpful. I am so happy with my Volvo and it makes it even better to own it with a group like this to help me.

Chet