'94 850 Turbo-Feels Low on Power

Post by **rspi** » 08 Feb 2016, 05:56

If your boost is consistent, and past the 1/2 way point in the white, you may have a more serious issue. I would double check timing and do a compression test.

IG-88A · Post by **IG-88A** » 08 Feb 2016, 07:42

rspi wrote:I would double check timing and do a compression test.

Thanks, Robert. I did a compression test maybe six months back, or so. These results were warm, WOT, with a borrowed gauge. 130, 130, 136, 132, 130. They seemed lower than they should be. I thought I'd remembered readings in the 150s being the desired range. But I could be wrong. But since my numbers were within 5-10 psi of each other, I was advised that these numbers were fine, and the low reading was probably the gauge itself. Let me know if this is okay, or if it seems suspect.

I also have a timing belt kit on the way from FCP. The all Volvo branded one. So timing will be addressed sometime within the next three weeks, if everything pans out.

I also swapped out the BCS/TCV, and checked my vac lines yesterday. I didn't notice any drastic change on the way in to work this morning. It still seemed to run fine. Just not as quick and peppy as it was during those two or three days last week.

I'm wondering now if I may have been experiencing overboost during the brief time that I thought I was getting optimum performance, and what I'm getting now and before is the way its supposed to feel. I have no friends with P80s, and I've never driven another one except my NA 850, so I have nothing to compare it to. There are no Volvo specialists around my area either, which is proving to be a real pain sometimes.

Post by **benpineapple** » 08 Feb 2016, 08:40

It definitely sounds like a computer or electronic related issue. When I first got my V70, it was mildly neglected in some areas. Especially the turbo. I would intermittently experience the functional turbo, seeming regardless of environmental or conditional factors (mind of its own).

I bought a new TCV, and about 20 feet worth of vacuum line. Pulled the turbo, cleaned it out as good as I could, replaced it, with new gaskets. Any and all vacuum lines going in or out got replaced. A lot of them visibly looked fine, but upon removing them, hard-to-see cracks were visible. After all this, the car felt brand new. The real testament to the tune up was when my wife was driving a week later (didn't tell her about what all work I had done), and she says "hey, why is the car way faster this week?"

Post by **abscate** » 08 Feb 2016, 09:00

...because you are hotter, darling....

IG-88A · Post by **IG-88A** » 08 Feb 2016, 09:15

Thanks for the advice, benpineapple.

I'll install a rebuilt turbo once I purchase the new exhaust. maybe I should just buy a new BCS/TCV as well. It could be that the spare I had on hand was faulty. I probably should just buy all new vacuum line, and replace every last bit of it at the same time. I know that even some of the new elbows I bought around a year and a half ago have already started to develop surface cracks in them.

Post by **abscate** » 08 Feb 2016, 09:24

Turbos oon these cars rarely go bad, and when they do, the rebuild kit is 1/4 the cost of a new one. There is a great DIY write up above, too.

IG-88A · Post by **IG-88A** » 08 Feb 2016, 10:06

Thanks, abscate. I already picked up a spare 15g at a junkyard last year, and had it rebuilt professionally. I didn't want to risk not getting it balanced right myself. My turbo seemed okay last I checked it. But I figured I might as well swap it out with the fresh one when the exhaust is replaced, just for peace of mind.

Post by **rspi** » 08 Feb 2016, 20:25

If your car is boosting like the video suggest, you do NOT have any vacuum or turbo tubing issues. It is very common for the intake tubing to get splits in it that open up while you are in boost, especially at the throttle body tube where the IAC inlet connects.

There is a chance that the car is loosing power due to engine wear. However, that does not explain the changes in performance.

If you disconnect your wastegate actuator arm, and tie the wastegate closed, the car will boost hard and will overboost if the turbo is in good shape. So you try that, be real careful. The thing about testing that is, if the car does NOT boost strong, you have an issue in the tubing somewhere.