Still overboosting
 

I'm still overboosting. Yesterday I was messing around and tried to pull vacuum with a hand pump on the bypass valve and it would NOT pull any vacuum. Someone mentioned that I likely have a wastegate issue so I pushed and pulled on that arm. I could hear air moving around the BCS but wasn't sure. Started to change the turbo vacuum lines but ran out of time.

Tossed everything back together, drove the car and had absolutely NO (0) boost. So, today I changed all of the vacuum lines, 3 on the turbo and the 3 to the BCS. While poking around I move the wastegate again and it felt very loose. Pulled the heat shield and the wastegate arm was loose, the pin rusted away and I guess I unhooked it yesterday. The thing about it is the hole is now clogged and I can't pin it. So I hooked it back up but had to put some hose on the arm to hold it in place.

After I put everything back together, the overboosting issue is worse. The cruise will make it boost past the white area on the boost gauge. So tomorrow I'm going to try to pull a wastegate from an S70 GLT and hopefully swap it over to mine.

Went to the junk yard with the vacuum pump today and the bypass valve and waste gate both pulled vacuum. So I took both of them off the 13T that was on the S70 GLT. I'll put them on my car tomorrow. Actually, I'll check my waste gate to see if it pulls vacuum. If so, I'll leave it and only replace the bypass valve.

When I got in the car this morning it was over boosting. This afternoon it is NOT. SMH

is it possible that the bcs is bad? Im not sure if that could cause an over boost issue but it might be worth looking into

Since I had no vacuum on the blow off (bypass valve) I pulled it and installed the used one I picked up from the jy. My old one did have a hole in it so, I'm guessing that has been my issue.

Now that I have that out of the way, it seems that I am under boosting. Not sure if I have a bad vacuum line going to my boost gauge or not but it seems to be showing me getting about 6 psi of boost. I guess there is a chance that my waste gate is out of adjustment. I'm going to use my ScanGauge to check my HP output. If it is lower than 210 hp I'm going to adjust or replace my waste gate.

After replacing the bypass diaphragm, it appears that I am no longer over boosting. However, according to my stock boost gauge, I'm only boosting 25% into the white which would be about 3 or 4 lbs. So I replaced the waste gate today with a used one. Still the same issue. My ScanGauge reports that I am producing 176 HP.

So, now I'm not boosting enough. My next plan of action is to replace the MAF and see if things change. If not, I will swap out my BCS with one from another car. Volvo (the dealer) no longer sells the BCS. I am also planning to purchase and install a turbo boost gauge to properly monitor boost.

I will keep this thread updated.

Today I start the car and bam! I got power. After several spirited runs off the line and otherwise, it looked like the car was over boosting a little, maybe to 12 lbs. So when I slowly push the pedal to the floor the boost peaks at about 14 lbs and backs off to about 12 lbs. This is going on pretty steady. If I punch it and suddenly go WOT, it will spike above the white range so I was a careful not to damage anything. As soon as it hit the edge of the white range I let off.

It is so frustrating that his issue is intermittent and I absolute did nothing to get the changed results. Urrrgggg!

I'm going to get a boost gauge and NEW BCS soon.

That is weird; you getting any codes at all?

You can replace the BCS with a TCV; the plumbing will be different but performance should be slightly better. You're always at the JY; pull one off of a '98 S70 turbo. I have the ard tcv on mine and it works well.

Here's the doc on hooking up tcv:
http://www.google.com/url?sa=t&rct=j...70138588,d.cGE

No codes, or at least no CEL. I have not checked the diagnostic port under the hood for codes. It seem as if the BCS is sticking and very slow to respond and regulate the boost. I heard that the TCV work, just wasn't real sure. I'll grab and try one tomorrow (make that today).

The dealers no longer carry BCS so one will have to go to an after market place or get the HD one that iPd sells.

It seems to boost pretty steady at 12 (guessing) but I can't just stomp on it, I have to gradually put it to the floor or it will jump to high before it comes back to a safe range.

Couldn't download the doc, my computer and programs are to old. Do I keep the colors the same? Do you know of a PDF for that doc?

If someone can open that doc and PDF it for me I would appreciate it. Free PDF converter at CutePDF - Convert to PDF for free, Free PDF Utilities, Save PDF Forms, Edit PDF easily.

Today I got a BCS and a TCV. The TCV had the blue and red dot on it so I know how it connects. I'm hitting the highway in the morning and I'll connect the BCS before I do (900 miles). Then, the next morning I'll connect the TCV to compare the two.

I'll video the boosting and post it here. This is what is happening now.

I am curious about if the new TCV and BCS will fix it for you. I am running 12.5 lbs on a manual boost controller and if I floor it, the gauge goes all the way to right. I have completely bypassed the TCV on my car(plugged in still so no codes though).

Ok, I believe I have finally found my boost issue, or at least I know how to get it to boost properly.

Someone (PO) installed an after market cat on the car. The rear o2 sensor is setting a P0422 code every so often. I think, when this code goes pending or something like that, the ECU dials back the boost to protect the cat. So, I can preform a force clear with my scan tool and it will allow me to boost nicely.

I guess I will have to install a better cat to stabilize this situation.

Honestly I would probably change that O2 sensor first before the cat.

I did.

Well, give that cat a good smack and see if anything is rattling :P