1997 850 T5 Boost Inconsistent

Jakoby · Post by **Jakoby** » 17 Sep 2013, 21:52

Read up on a few of the blogs after doing an intercooler exchange. Kept the stock system just replaced my very cracked one with a perfect one from a scrap yard. 100 bucks and a 6 month warranty, can't really beat that. Didn't take long to swap it out, I think 4 hours. So i believe I bought the car 8 months ago with the cracked intercooler so not really knowing what to expect, I fired up my black panther, and proceeded to let all the fluids to get into the flow of things. Started driving with a light foot, I then remembered how heavy my foot really was and the car came alive. I had never felt it run the way it did it was quite glorious and relieving I actually had well spent money for once. The next morning half way to work a quick 30 min drive with 3 stop signs out in the country. I stopped at my last stop sign and got on it and the boost was the same as when I had the cracked IC. Thinking thats what happened I checked it out and it was fine. The way home the boost was back and it stuck around for 2 full days. Then again today it faded away. It never happens when I am on the throttle only after I wanna boost it back up. With the cracked IC it was a 1/8 of the way into the white on the stock gauge. With the replacement it was 3/4 - 5/8 depending. Have screwed with the wastegate rod a 2 turns, trying to find my happy place and seeing if it affected my boost issue. have checked all VAC lines and all charge pipes. The rubber ones are old and worn out, very flexible and squishy, time for some silicone i think maybe even the RICP. Anyways thinking it would kinda fallout of the boost if those were the issue, looked into the WG vaccum line. Pulled of off from the BCS and had MAXIMUM pressure as expected. So my real question is, is the BCS bad or do I potentially have another funky issue.
This is my first volvo and I love the thing. I love working on it and figuring it out. It's the most fun car I have had. The wagon really gets me. Went from a 01 S-10 4.3 Vortech to a 91 Civic hatch to this and I am very impressed with it. It still gets 22 mpg with stop and go. And on my recent trip to Oregon on the Hwy I went 75-80 and got 27!!! I understand it was running lean as well, but the mileage didnt change to much.

Any help would be greatly appreciated.
BCS? Or look further?

Post by **matthew1** » 20 Jan 2014, 20:20

It's hard to say when so many of the parts are so old. Fuel delivery items (and most everything) are 18 years old now. Not saying you need to replace the fuel system... just saying this problem is hard to diagnose.

You have started with a good description.

Heat soak: is the heat shield in place? It's a metal shield with 3 bolts mounted above the turbocharger.

Anything that could be affected by heat is suspect.

Bump for an old thread whose author (too kindly) doesn't want to spam us. (Jakoby and everyone: bumping is fine here if you don't get a response.)

Post by **matthew1** » 21 Jan 2014, 13:10

Jakoby, what haven't you done compared to the Stage 0 list?

Jakoby · Post by **Jakoby** » 24 Jan 2014, 23:05

No heat shield hasn't been on it since i bought it.
I have replaced
Sparkplugs
fuel filter
PCV system
MAF
Both o2's
CBV
BCS
all vac lines to bcs
silicone boots
have looked over all other vac lines
some of these I did because I didnt know when they had been replaced.
Others I had tested with a multimeter plus the codes.

I now get a p0422 main catalyst below threshold. clogged cat?

Also how do I bump I'm new to forums.
Thanks

Post by **abscate** » 25 Jan 2014, 04:34

You bump by replying to your thread with the word "bumps"

Post by **erikv11** » 25 Jan 2014, 08:13

p0422 is a tricky code, it can be a lot of things (intake leak, exhaust leak, bad cat, bad rear O2 sensor, others).

You do mean p0422, and not the ever-common p0442, right?

I would get and install a heat shield just to eliminate heat soak as a problem.

Jakoby · Post by **Jakoby** » 25 Jan 2014, 10:00

Thank you abscate. So simple

Yes definitely P0422 erikv11.
Will do headed to scrap yard here soon today. Never heard of heat soak but I know the engineers didn't put a shield there for no reason.
Oh and also replacing subframe today will post pics of that adventure :/

Jakoby · Post by **Jakoby** » 31 Jan 2014, 14:19

Anyone here know what the pressure should be in the exhaust before the CAT?

Jakoby · Post by **Jakoby** » 13 Feb 2014, 17:20

Matthew I love the precode portion of this site that you "made up".
The spacer seems like a good thing to try. Thank you for all the help here and on the face space.

Post by **matthew1** » 14 Feb 2014, 11:08