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Supercharged/TurbochargedThe increase in air/fuel pressure above atmospheric pressure in the intake system caused by the action of a supercharger or turbocharger attached to an engine.
I have been running into an issue with my SC setup on my Maxima after replacing my Blitz BOV (leaking unit) with a Maxflow Race unit. Basically, the issue I have been encountering is the RPMs dropping very low upon letting off on the accelerator coming to a stop (5-speed). The RPMs would sometimes drop so low that the car would stall. Initially, I had though maybe the IACV was bad and swapped in a known used working unit with no change. I found that if I tightened the BPV adjustment (increasing spring pressure), the problem would lessen and then eventually go away entirely after a point. However in doing so, the valve would not be fully open at cruising vacuum.
The phenomenon is similar to venting to atmosphere on a pull-thru MAF setup, however I am running a blow-thru MAF system and the BOV is placed over 6" away from the MAF. I've been trying to do a search of people having similar issues but I cannot find anything. I was wondering if you had any insight on what the issue may be (with a possible solution) or have encountered this problem. I also just shot an email to Vortech to see if they had any idea. Any help would be much appreciated.
The Maxflow unit is a bypass valve that I consulted with Vortech in using before making the purchase. According to them, it should work fine with the SC since I am running a blow-through MAF setup. That unit is also being utilized on the SC upgrade for the FRS/BRZ SC setups and I have not heard of any issues that they have.
IMO, the Vortech bypass valve is the best choice for our cars. My question is, did you buy it new or used? I have this exact valve on several of my Maximas w/o issue.
Which side of the MAF is the valve on? Closer to TB or closer to supercharger?
This is so weird that you're having issues with the Vortech unit.
PCV fitting on the VC towards the front of the car is plumbed into the pipe between air filter and supercharger. I will have to check where the BOV vacuum source is tapped into, but it should be correct as there were no problems with the BOV operation with the Blitz unit.
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On your BOV unit, how tight do you have the screw moved down? My unit is using the stiffer spring that comes with all the newer models, and I am about 2-3 turns in past the point of initial contact where screw starts getting resistance. I still get a bit of dipping RPM when letting off the throttle completely.
Temporarily changed over to a Greddy RS valve to resolve the issue. Still haven't been able to figure out why the Vortech unit is stalling the car. I am going to mod up another pipe from the SC to MAF and try moving the BPV mounting position closer to the SC to see if that will solve the issue.
On a side note, the Greddy RS valve is extremely quiet (even VTA). Had to remove the shorter spring in order to get it to start opening at 10" of vacuum (fully open at 17"). Using the shorter spring only, it would open a bit early at around 5-7".
Temporarily changed over to a Greddy RS valve to resolve the issue. Still haven't been able to figure out why the Vortech unit is stalling the car. I am going to mod up another pipe from the SC to MAF and try moving the BPV mounting position closer to the SC to see if that will solve the issue.
On a side note, the Greddy RS valve is extremely quiet (even VTA). Had to remove the shorter spring in order to get it to start opening at 10" of vacuum (fully open at 17"). Using the shorter spring only, it would open a bit early at around 5-7".
Make sure the BOV is fully open at idle and has a good vacuum source. Im sure you know the SC is always spinning so when off throttle that air needs to go somewhere. So make sure it opens fully.
Im using the Vortech Maxflow and even upon adjusting it in the past so that it opened a little less, it did not affect my idle ( auto ) or cause my car to stall.
In addition, 12" away from the MAF should be efficient enough as most of us here have the BOV located in the same position. Moving it, I highly doubt will change the issue you're having.
What engine management unit are you using?
oh btw the way your FVC is piped is how I want to install mine. This way its all metered air going back into the engine. I think it makes for a more efficient tune.
Last edited by maxprivate; 09-07-2015 at 06:50 AM.
Hello all fellow S/C drivers. I finally have pieced together and installed a vortech supercharger kit but not the stillen setup. Its kinda of a Frankenstein setup. I am having an issue with the car even starting. My buddy who has installed most of it think it to be a vacuum leak someplace. The car starts up and either stalls immediately or surges up to 4000 rpm runs like a bag of **** for about 2 seconds then stalls. I have the walbro 255 installed, the GFB is currently set to 100% VTA because we have not set up the return line to recir the air. I am sure I am missing something to add here.
05-25-2015, 03:37 PM
