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93 sc400 supercharged, please help with pcv system!
I have a 93 sc400, it is supercharged. It idles really high and the way the last owner piped in pcv makes me curious. They piped in an overflow tank with one side pcv and the other vacuum with a breather filter. Every time I start it smoke comes pouring out pcv tube. Rings bad? I unplug the maf sensor and everything goes away but it has no *****. Any help would be great. 1uz!!!!
Running with the maf unplugged is a bad idea while the superchargers on there. Unplugging the ecu (if its a stock unit) reverts to speed density where it bases timing and injection off of tps and ect, it assumes air pressure and temperature. It was designed to run NA on the speed density but if your forcing air through it the timing will be off and the car won't know, bad things could happen.
The smoke coming out of the pcv is normal, in that the gas is caustic and that is why it must be removed from the crankcase. If it goes away completely when warm then I don't know. But either way having the pcv vent to atmosphere is not great, you want to pull it out of the crankcase using vacuum. If I'm picturing it correctly, one side has a catchcan and the other just has a little filter?
So today I routed the passenger side plastic elbow from valve cover to throttle body as stock. I then piped in vacuum from some weird pipe that my stock sc doesn’t have with a t, one goes to pcv, one vents and the other goes to intake. The problem I’m having is I have a 3/4 I have is I have a 3/4 inch hose sucking treamendous amounts of air. If I put it anywhere other than open it stalls.
So today I routed the passenger side plastic elbow from valve cover to throttle body as stock. I then piped in vacuum from some weird pipe that my stock sc doesn’t have with a t, one goes to pcv, one vents and the other goes to intake. The problem I’m having is I have a 3/4 I have is I have a 3/4 inch hose sucking treamendous amounts of air. If I put it anywhere other than open it stalls.
i have the pcv valve routed to back of supercharger and an open hose coming off a t to both. Drivers side is routed as factory. I just bought this car. It idled really high and ran like crap, I’ve got it running good but it stalls a lot.
Tube from pcv, intake port on supercharger, to the hose that has to be sucking unrestricted air.
Passenger side, tried redoing it to factory
If I plug that rubber tube coming from pcv and port on supercharger it stalls immediately. I can’t even put a filter on that hose, tried hooking it up to cold air intake, stalls immediately. The car had both pcv and vent on passenger side vc going into a vented catch can. It smoked and ran like *****.
The iacv hose circled goes to the 3/4 bung on the intake circled.
I'd take the 5/16 pcv hose on the driverside valve cover and route it to the smaller bung on intake tube.
I think your stall issue is the motor injesting unregulated air from iacv, on a normal car it pulls that air after the Maf so the ecu expects to only injest air it's already metered. Also are those bungs on the intake tube open to atmosphere? If they are it's the same issue of investing unregulated air.
Either way the iacv should plug into that 3/4 bung on the intake, and it will function the way it would've stock.
I will try it today. I’m a mechanic, I also thought about unmetered air. If I plug both holes in intake it makes no changes. Do I plug off intake port on the supercharger?
I will try it today. I’m a mechanic, I also thought about unmetered air. If I plug both holes in intake it makes no changes. Do I plug off intake port on the supercharger?
Intake port on supercharger, as in the iacv? You can, just plug it and adjust the idle screw. It's what I'm currently doing with my turbo setup. But I don't see the point when you can loop it to where it belongs.
Your passenger side with the valve cover connected to the bottom of the throttle body is how it would be stock.
I imagine plugging those ports on the intake before the throttle body didn't make a difference because the motor was still injesting a bunch of air at the iacv. And I noticed these cars will idle with the iacv not hooked to the intake system but once you give it gas the motor dies, so the Maf might not be in use at idle and it runs speed density until the rpm picks past 1000 or something weird. Which would mean that the unmetered air is only a problem after idle.
Yea, I have a na 92 sc400 that I’ve been parting out, I was trying to get the pcv similar to stock but the supercharger has a port that sucks massive amounts of vacuum. I will try to just plug it off. The way this car was set up has me so confused, they had brake booster vacuum applied to vented catch can and both pcv and vent on passenger side. It smoked like crazy.
05-22-18, 08:08 PM
93 sc400 supercharged, please help with pcv system!
