Turbo control valve

nut3y

Are the the square and circular turbo control valves interchangeable? Cant find the circular ones anywhere but the square ones seem plentiful. Would an older 850 accept the square one that comes on P1 cars? They seem like pretty simple devices but just want to make sure. Running a m4.4 ecu if that makes any difference.

Ex850R

Use the Pierburg one from Volvo or elsewhere , no , P1 car ones are not at all useable.

nut3y

My bad meant to say P2 platform. So something like this? https://www.fcpeuro.com/products/volvo-boost-pressure-valve-genuine-volvo-30670449

Ex850R

Exactly what model and year and engine is it for.

nut3y

1994 850 T-5 B5234T originally m4.3 but has m4.4. Comes stock with the cylindrical one, but it seems they are different.

hamsandwich

I use this one in 850 also with m4.4

I have tried the standard round one, a Mac 3 port I made up, and this pierburg one.

The pierburg seems the better choice for me anyway, and works well with the M4.4

dmm

I temporarily replaced my 850R’s original round unit with one of those pierbergs in an attempt to isolate an erratic boost issue. A mate fab’d an aluminum bracket to mount it on the side of the air box using existing bolts.

I ended up reinstalling the original round unit. @VPT02 reckons the pierberg and m4.3 mightnt always play nicely at the upper end.

nut3y

Might grab the pierburg box then, also does the CBV spring get weaker with time? Having some pretty bad boost fade problems even with an MBC. Wondering whether or not I should get the IPD kit with the springs or just try to find a diaphragm by itself.

dmm

The Forge units look swish but I opted for one of these Kinugawa kits

https://www.ebay.com.au/itm/263690802234

nut3y

Hmmm, is that spring (assuming it's stock pressure) enough for 14-15ish psi, or doesn't it really matter?

dmm

Its probably unsuitable for pressure levels much above stock

More here

https://ozvolvo.org/discussion/11729/blow-off-valves-and-compressor-bypass-valves-for-the-850-turbo

nut3y

Yeah I might go with IPD and run the blue spring, seems like the best option.

hamsandwich

I use the kinugawa cbv kits, I currently have a blue spring in it, but have a red spring ready to go in when I can find the time. They are cheap and ship very quick.

If your diaphragm is original there is a very good chance it has pin holes in it too.

nut3y

hamsandwich
I use the kinugawa cbv kits, I currently have a blue spring in it, but have a red spring ready to go in when I can find the time. They are cheap and ship very quick.
If your diaphragm is original there is a very good chance it has pin holes in it too.

Yeah original 365,000kms, probably nothing left of it although the wastegate actuator still holds vacuum surprisingly, will most likely need to be calibrated however.

rado

I ran the oem round tcm then the ipd hd one

but was noticing spikes , so went with the Pierburg

Now waiting for this instead

I did find the Pierburg better than the IPD HD item , stopped the spiking

Running Forge actuator and Forge recirculation valve as well and all running very good

nut3y

rado
I ran the oem round tcm then the ipd hd one
https://cdn.ozvolvo.org/uploads/656/BKWNCFJ497RI.png
but was noticing spikes , so went with the Pierburg
https://cdn.ozvolvo.org/uploads/380/1VQNNS4HIAWC.png
Now waiting for this instead
https://cdn.ozvolvo.org/uploads/908/DD887V6IIKMS.png
I did find the Pierburg better than the IPD HD item , stopped the spiking

I currently have a MBC installed but it builds boost too quickly. Looking at the logs the ecu is pulling quite a bit of timing, even with richer fuel maps and retarded timing. Boost goes way up to 15 psi in 1st somehow and then falls to 10psi in second which then dwindles down to 5 by around 4800 rpm or so.

nut3y

Went ahead and bought the kinugawa repair kit, green spring (5-15psi) and a mac solenoid for $120 shipped. Probably should have gone with the pierburg solenoid but $47 for the mac was just too good. Pretty sure that's what IPD uses for their "HD" TCVs anyways. I'll use the MBC in parallel to manage any spikes.

hamsandwich

If you got the Mac without the plug like I did it's just one of these.

If you can log with tunerpro then you can tune boost spikes out and ditch the MBC altogether, after you get rid of the timing pull, if you can be bothered it is quite time consuming, but good fun and great learning curve

nut3y

Yeah I was wondering what connector it used, that'll save me from messing with the wires. Not sure if my neighborhood would approve of any more tuning, I'll just take to where all the old farts have their 5 investment properties. Car doesn't have a cat and it's quite loud under load, never realised that the cat did so much muffling, thought that was the mufflers job.

nut3y

Does the polarity matter for the MAC solenoid? Can't seem to find anything that distinguishes the wires so I'd assume not but want to make sure so I don't fry anything.