I will start in the beginning and try to give as much info as possible. I have a 94 850 turbo and I also have a parts car with a bunch of ipd stuff on it. One day I took a look at the ecu and it had a pink sticker on it that says something like 96 turbo so I checked the numbers and they matched so I tried it at the time I had no boost gauge and my seat of the pants dyno said it is tuned and it also seemed like the stock boost gauge was going higher and even chirped the tires shifting into second. All was well for over six months then the car started to make aflutter at full throttle and then progressively got worse. So I then bought a cbv. Boost controller boost gauge silicone turbo vacuum line all from ipd. Put it all on and the flutter was all but non existent but from time to time would still do it. Now today its doing it at full throttle again. In first it starts around 9.5 psi and I have no idea why can't find any other problems. No checkengine or nothing. I'm confused . Since I got the gauge the car always boosts around 9.5 but spikes 15 for a split second when it shifts. If anyone knows anything about this please help. I'm not sure if I'm giving enough info to diagnose my problem.

 

Kind of hard to diagnose from the description but it could be a bad Bypass valve (CBV). It also could be a hole or tear in one of the intercooler hoses. It also could be a bad turbo. Pull the intake hose off and check for shaft play in the turbo, spin the compressor and make sure it spins cleanly. Please have the engine off when you do this!!

 

the compressor bypass valve is a new HD ipd unit. I will pull it and check the plunger for any damage is there any thing else that can go wrong with the cbv?

 

also is there any way to test for boost leeks?

 

How is the exhaust? It the catty fine?

 

Exhaust seems to be fine,no check engine light. car only has 108000 and its a 94. drove the car again last night and it ran flawless. 9.5 psi at wot then around 4500 rpms hits like 12-12.5 i think it may be an r ecu. I guess il see what today brings ugh!

 

Check that vacuum hoses on the Turbo Control Valve (attached to the airbox). Clean the TCV.

Make sure also that the vacuum hoses on the Bypass Valve are good. You said Bypass Valve is new -- is it set/adjusted correctly?

 

I have all new silicone vacuum lines. It has a new ipd turbo controler. It has a new Ipd CBV and i do not know if you can adjust any of these things other than putting the biggest suplied spring in the CBV I put the smaller one in it I think it was blue. And the turbo controler has a little red button on it but have no idea what its for.

 

CBV (called Servo in Volvo-speak) has a certain setting for the Wastegate arm/rod. I was losing boost some time ago and did that adjustment, which seemed to take care of my. Since you have an IPD Controller, your should find out the specific PSI values, if any different from stock. Here is stock though:

This is per Volvo's documentation:

Basic Adjustment Of Pressure Regulator Push Rod
1) Remove locking circlip from end of push rod. Connect
Pressure Gauge (999-5230) and Pressure Tester (999-5496) to pressure
regulator. See Fig. 1. Increase pressure to 1.7-1.9 psi (.12-.13
kg/cm�� ). Press wastegate lever against turbine housing, closing
wastegate valve.
2) Adjust push rod length so push rod fits exactly over
wastegate valve lever. Install locking circlip, and tighten push rod
lock nut. Remove pressure gauge and tester.

I used a Mityvac.

 

You should check the surface of your compressor housing where the CBV valve seats. It can wear out and end up with a groove in it that can leak.

 

Thanks that does seem to be the most logical because its not an all the time thing. What do i do if there is a grove in it can it be machined out or sealed some other way or is the turbo toast.

 

It has to be machined down. This was the case on my housing and I used a bench top belt sander and very carefully took about a mm off it. I thought I took pictures but cannot find them.
I dont know if this is the reason but you should at least check the surface to see if its grooved.