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Diverter valve

originally posted by Me in the OP
I don't care for the choo choo sound

It's just less plumbing for me. This is my only car and I need it functioning as I have school and work every day of the week. Forgive me for trying to cut corners. I'm just working with what I got.
 
No the valve won't work as a blow off, it is open when the car is idling. at least mine is
 
Take a look around at the way the recirculating valve is done on a 240 turbo Group A car. They use a high pressure version of that valve. The Saab valve is ok but it is only rubber inside. So it won't stand up to high boost and isn't worth messing with. If you want to stay with a production car part. Use the Porsche 911 turbo valve. It looks like the Saab valve but has a metal insert to help it work with higher boost. They are not expensive. Something for a 1993 911 turbo would work. I forget the part but it is easy to find.

I eventually upgraded to the Saab Forge valve. It too is a sealed valve and replaces the above ones without any changes.
 
I set it all up and drove it today. I think it's restricted because the holes are too small and the air isn't really bypassing quickly enough. It still flutters slightly.
 
Alright so everything is put together, including the recirc valve, but it still dies on let-off.

I've got IAC connected which makes a good effort to try to save it, but usually fails as it isn't quick enough.

I don't understand why it still dies even after I have the valve set up. I included a picture of my setup, trash talk my garden hose all you want but at 2$ a foot, I can't complain.

I was thinking that maybe the recirculated air is entering too close to the maf? would this matter...? anyway

https://ibb.co/f6tDZ7
 
My recirculated air comes in 3 inches from the maf with no issues. I had the same-ish issue when I +t my car, it turns out the way i routed the pcv system, it was creating a slight vacuum leak making my car die on let off. How is yours set up?
 
My pcv is a separate system and doesn't use vacuum currently (been switching between using vacuum and not to see effects). Maybe tomorrow morning I'll boost leak test it and see if there's any leaks.
 
I have evo, silvia, subaru, skyline, and GTR BPVs on the shelf here, and have run the GTR up to 18psi (Holset) with zero issues, and without modifying it in the first place. The collection has slowly formed over time so I can put a "leaks at" number on each one with the help of my compressor and some time in the shed. GTR ones have 38mm outlets! More than ample for my Holset HE351CW, or pretty much any turbo, actually. How much (psi) are you going to thrash the Holset/rods/pistons? Or are you worried about outright flow? If the latter, think of it as a serious leak to ensure no serious pressure spike can occur.
 
Does the car idle normally?

To establish a baseline, I'd disconnect the wastegate actuator and wire the wastegate OPEN (no boost) and see if the engine operates normally on/off throttle. I suspect that there is a vacuum leak somewhere that shows up under high vacuum conditions (off throttle decel).

Also, your recirc valve plumbing has a lot more hose than is really needed. Typically they only connect between the turbo inlet and turbo outlet vs coldside piping.

IMG_0666.JPG


VS

 
The question is, do you kill the pressure spike at the throttle as it occurs, or at the compressor as it impacts the blades, I'd prefer both. Plumbing isn't too heavy. Good advice re the other diagnostics, though :-)
 
I've moved the maf over to the cold side which seems to improve it. BUT

I'm trying to get a bov so I don't have to fuss with this diverter valve any more.

I've been looking at the HKS ssqv (space ship model) because it's a pull type and I remember reading in a different thread that it shouldn't leak at idle causing issues (is this true?)

If it does leak at idle, which seems to happen with a lot of bovs, should I have it before the maf or after ? My thoughts are that if it's after the maf, it'll be a huge vacuum leak and cause lean issues, but before the maf, it should theoretically run the same

Ive been reading up and been finding some wishy washy information on this so humor me.
 
I don't care for the choo choo sound and don't want to mess around with stalling.

I'm trying to get a bov...
:???:

Have you tried a method of taking the turbo boost out of the equation and verifying that your car doesn't have the stalling issue regardless of what kind of bov/recirc valve you use? Is your engine stock otherwise (injectors/chip/cam timing, etc)?
 


You mounted your recirc valve backwards. Flip it and it should work just fine, just kinda worried about that silicone holding under boost...
 
Since I've moved the maf, I've done away with the recirc for now. It'll just be a bandaid until I can get a bov so I don't feel like putting it back in.

just kinda worried about that silicone holding under boost...

You're very wise to think that, it blew open on the way back from college and I had to run her home with an afr of around 9:lol:
 
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