ECU controlled BOV via ECMlink
So to start this off I must first give some background information as to what this is, and why it is benificial. This mod requires that you have either a 1g dodge garage modded (Gus mod) BOV, or a BOV that has 2 nipples. This link provides more information on how to preform this mod.
DDG- Talon BOV mod for HIGH BOOST
The purpose of this mod is that by rerouting that hole under the BOV flange to vent it to the atmosphere, you essentially increase the BOV's ability to stay closed under pressure. Reason being is that before, it had pressure pushing from underneath the diaphram trying to push against the internal spring which was trying to hold the valve closed. Seeing as how the pressure is no longer trying to open the it, you now have a BOV that should be good for 30+ psi depending. It also makes the BOV A LOT louder, for those of you that enjoy that sorta thing.
The only downfall to this modification is that it takes slightly longer for the vacuum source to pull against the spring to open the valve. This results in a flutter sound as you shift or get out of the throttle sometimes. I drove my car for about a year this way with no ill effects, however I must say that this is not a good thing for the lifespan of your turbo no matter how you look at it. That pressure staying inside the intercooler piping with want to "push" against the compressor of your turbo, but in the opposite direction, killing your throttle response and eventually your thrust bearings. So if you only race your car, you probably don't need to worry about it. If you DD your car, the longevity of parts is critical.
On 2g's, there is a Fuel Pressure Solenoid (FPS) located on the firewall next to the brake booster. This sensor allows the ecu to temporarily enable a rich start and nothing else. Most people such as my self just unplug the vacuum lines and leave the sensor. Well, ECMlink provides outputs so that you can control the actuation of this vacuum valve according to your user defined settings.
Basically, you intercept the pressure going to the bottom of the BOV so that at high boost, the BOV only sees pressure on the top, forcing it to stay closed. But when you lift off the throttle, pressure is again applied to the bottom to help open the BOV more quickly.
I used the nitrous controls in DSMLink to control the fuel pressure solenoid. Basically, you feed a pre-throttle plate pressure source (“A” port on a 2G TB or the “A1” port on a 1G) into the “input” side of the fuel pressure solenoid. Then feed the switched output to the bottom feed of the 1G BOV. Using the standard nitrous controls in DSMLink you can then have the BOV completely shut with high throttle, but completely stock at all other times. The picture below illustrates which port on the fuel pressure solenoid goes where.
If you're going to run more than, say, 20-21 psi with this mod, and you plan to do more than drag race, then you'll need to pay a little more attention to the throttle activation point. In my case, I wanted to run the car at the road course with spikes to 23psi, holding a pretty constant 21psi after that. The problem is that the 1G BOV will open on its own around 19psi. I couldn't just plug in a really high TPS value into the nitrous controls because there were plenty of times I was modulating the throttle below that point but still building more than 19psi. Just using a high TPS value resulted in the BOV opening at odd times, defeating the purpose of the mod.
To work around that, simply find the TPS point needed to build, say, 18-19psi on your car and set the activation point around that. For my setup, I was hitting 20psi with 45% throttle above 3800 RPM in 3rd gear. So I set nitrous controls to 40% TPS and all worked well. Now, above 40% TPS, I have a BOV that will stay closed no matter how much boost I build but will open like stock below that.
NOTE: I want to point out that this still isn't an ideal control mechanism. Ideally, you'd want to have a differential pressure sensor wired across the throttle body to control the BOV properly. But triggering off TPS at or around the cracking point of the BOV seems to suffice for the most part.
Before I found out about this mod, my plan was this.....
This would allow me to screw in a bolt sealing that vacuum nipple when I wanted the BOV to function like the DGM but I could easily unplug that nipple and throw on the vac line when I wanted to valve to preform like stock. Essentially this mod does just that electronically via throttle position and RPM. As a result I have a VERY cheap BOV that will not crack open due to the pressure. If you already have the 1g BOV, this mod should only take about $15 and an hour or so of your time. These BOV's go for $20-30 typically and are super strong and reliable, so it is still worth it even if you need to purchase the valve.
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