Boost Operated Blow Off Valve - Boomba Racing

[TEXAS HEAT]

I've been running the BOV for about 4 days now. Got it completed Saturday evening along with the Levels FMIC. But i've run into an anomaly which I am trying to sort out the cause of.

Under light load conditions, while cruising at a relatively constant speed, some times the BOV will remain open continuously. It's loud enough that I can hear it easily with the windows rolled down. It will remain open even as I give it more throttle for a short period of time, which becomes very obvious as there's little response form the engine and the vented air becomes even more audible. I cannot reproduce this occurrence on demand, but the last occurrence (yesterday) I noticed there was no boost or vacuum (bouncing around the 0 mark) while the issue occurred, which coincides with the fact that the valve is open, hence why the pressure gauge is reporting atmosphere instead of vacuum or boost.

Some possible causes:

1. Solenoid valve in the control manifold is sticking

2. BOV plunger is sticking

3. PCM software has a bug, possibly too much hysteresis, causing the valve to open, but the lower trip point to close it set too low, thus we're operating in the dead band of the hysteresis bounds and hence the valve remains open so long as the conditions don't vary significantly from the initial occurrence which caused it to open.

4. PCM software is functioning as intended and this is a design oversight on the part of Boomba. It is possible that the PCM may be holding the valve open by intent in these conditions to bypass the turbo while under very light load for fuel economy purposes, if the turbo isn't spooling enough to produce boost, it serves only as a restriction on an engine operating in the NA region (pressure at the throttle body is a vacuum, not under pressure when the turbo being driven fast enough to generate boost). The bypass tube between the compressor inlet and outlet is large enough to support adequate flow at low loads.

At this point in time I have not had much time to diagnose the cause of the issue, but have only become aware of it. Cause number 4 seems to be the least likely, but I have no proof of the factory PCM software's architecture to rule it out completely. I also have less visibility of the factory DV operation as it's not audible and I'm now aware of any PID's that monitor the BOV state. It may be a blind output, meaning the PCM drives the valve but has no visibility of it's actual state and operates by assumption that the valve is actually in the position commanded. The PCM software would certainly be aware of when it has commanded the valve to be in a particular position, but the valve may not actually be in that position.

The most likely would be causes 1 or 2, which I may be able to resolve by having Boomba replace the components or at the very least assist in diagnosing the issue. I would like to first test the vacuum operation of the valve by using a negative pressure sources to manually drive the plunger. I can use a manual air pump to test the pressure required to force it to return if it does not return under atmospheric (which it should due to the return spring). The valve should remain closed under atmospheric and under boost as the holding strength is still the spring rate (the turbo outlet pressure has a net 0 effect on the BOV plunger as the plunger is held shut by the same pressure, thus the mechanical spring in all instance is the holding closed pressure).

The Solenoid might be a bit more tricky, but I'm sure I can come up with an appropriate supply voltage to operate the mac valve. BTW, anybody know the operating voltage of the MAC solenoid? It would most likely be 5V or 12V, I could test 5V first, if no operation then 12 would be appropriate.

Most likely 12v if this is like a N20 solenoid.

The factory ECU does see this value directly as (1) BPV Mode – Bypass valve mode. (0=Closed, 1=Open).

The only way I can see to determine what capacity the ECU controls this is to datalog under what conditions it is opened and/or closed.

I thought this might be an issue with the Boomba BPV if the ECU is commanding it to open based on a predetermined condition and it is not opening and/or vice versa.

My thoughts are possibly a bad solenoid. You can test it by hooking it up to your battery at 12v and watch the actuation of the solenoid itself to determine if it's working properly. Check all electrical connections, did you disrupt any grounds during install?

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[JStang15]

Under light load conditions, while cruising at a relatively constant speed, some times the BOV will remain open continuously. It's loud enough that I can hear it easily with the windows rolled down. It will remain open even as I give it more throttle for a short period of time, which becomes very obvious as there's little response form the engine and the vented air becomes even more audible. I cannot reproduce this occurrence on demand, but the last occurrence (yesterday) I noticed there was no boost or vacuum (bouncing around the 0 mark) while the issue occurred, which coincides with the fact that the valve is open, hence why the pressure gauge is reporting atmosphere instead of vacuum or boost.

The ECU does this by design. I'm not sure exactly what the reasoning is (possibly fuel economy as you mentioned, possibly as a preventative measure against LSPI to prevent boost from building while cruising at low RPM). It happens with the factory BPV as well, but the sound is not noticeable due to the re-circulation/factory intake design. I think this is one of the reasons many people prefer a traditional blow-off valve not controlled by the ECU. The ECU will sometimes open the valve at times you wouldn't expect.

 

[TheLion]

I figured it was most likely a 12V solenoid, however 5V solenoids are also common. It's really hard to say without knowing how the ECU output is designed, I"m guessing it's a simple low side drive using an N-channel MOSFET, which is pretty standard for driving coils. Problem is, if it's a 5V solenoid and I hook it up to a 12V source, poof goes the coil...

I didn't see any markings on the MAC solenoid, otherwise I would just look up the specs, appears to be a run of the milll unit with maybe a custom manifold.

JStang, that was one of my possible causes, that there's nothing wrong with the system and this is normal operation of the PCM / ECU. With the factory valve we would be none the wiser as you mentioned. Is there a PID to monitor the valve? If I could log the PID for any changes and compare it to pressure I could confirm this to be absolutely true.

 

[EnFOURcer]

The ECU does this by design. It happens with the factory BPV as well, but the sound is not noticeable due to the re-circulation/factory intake design. I think this is one of the reasons many people prefer a traditional blow-off valve not controlled by the ECU. The ECU will sometimes open the valve at times you wouldn't expect.

CORRECT!

There are multiple "reasons" for this.

 

[Juben]

TheLion, the valve opening like that is completely normal. Why do you think I was asking questions about running it without the solenoid in a purely mechanic state. Replace it with the factory BPV and keep the hose off. It will do the same exact thing. Many people have upgraded to a mechanical valve just to get rid of that hissing.

That's why I said that I'd let Adam explain it a while back. He can explain what Ford was doing with the programming in making it open like that.

Forget about troubleshooting it. The only way to fix it is to go purely mechanical and turn off the electronic control within your tune. If Livernois' software is as far past other tuning software as they state, then they should have no problem updating your tune to remove the factory control.

Edit: I wrote this from my phone and the latest replies didn't show. Same thing though and the above still applies.

 

[TheLion]

I came to realize this once I was able to reproduce the occurrence on demand. If I regulate throttle based on boost to hold at atmosphere for 10 seconds it will open and remain open as long as I can regulate at atmosphere.

The hissing actually does not bother me now that I understanding what's going on. However my concern is this: contamination of the intake. When the valve is held open, there's a wide open pathway right into the intake tract.

Normally when the valve is venting for surge prevention when letting off the throttle, we have a high volume of air being expelled, which in itself is a barrier better than any filter. However when the valve is held open during very low boost, there's much less volume being expelled. Certainly there's enough to cause audible noise, but my concern is that is it enough to prevent contamination?

Removing this function in the custom PCM tune would certainly be one solution, but for those not tuning their PCM or using the Ford Racing tune, that's not a viable solution and Boomba markets this as compatible with stock cars.

If they have any testing or information on this which could shed some light as to the volume of air being expelled, that would be great. Another solution would be a bell housing over the top of the valve (like a dome). I've seen industrial bleeder valves, which serve a similar function as an automotive BOV, using bell housings over the top to prevent contaminants for entering. A filter would be another method, similar to the breather filter UPR uses on one of their catch can designs (aka same paper media filter as your intake filter). Foam would work too.

 

[TheLion]

TheLion, the valve opening like that is completely normal. Why do you think I was asking questions about running it without the solenoid in a purely mechanic state. Replace it with the factory BPV and keep the hose off. It will do the same exact thing. Many people have upgraded to a mechanical valve just to get rid of that hissing.

That's why I said that I'd let Adam explain it a while back. He can explain what Ford was doing with the programming in making it open like that.

Forget about troubleshooting it. The only way to fix it is to go purely mechanical and turn off the electronic control within your tune. If Livernois' software is as far past other tuning software as they state, then they should have no problem updating your tune to remove the factory control.

Edit: I wrote this from my phone and the latest replies didn't show. Same thing though and the above still applies.

Juben, no I was not aware of exactly what your were referencing as all you stated was "opening at weird times". That could me anything and I did not draw a direct correlation between your description and what I was experiencing, at least not until today.

Regardless, there are still merits to having an ECU controlled valve. There IS a reason Ford is doing this, the most likely I can think of fuel economy and emissions. However this could also be aiding in reducing excessive manifold heat, at low rpm we have a lower exhaust flow, however the turbine also posses a larger restriction as there's not enough volume of flow to really get it rotating at more than maybe a couple hundred to a couple thousand rpms.

This may create a disproportionate back pressure / restriction relative to the engine rpm. Venting alleviates that back pressure as the turbine is no longer compressing air, but just flowing air at the rate of the intake. Any excess pressure other than the draw of the engine operating as NA would be expelled. Even though my boost gauge reads 0, that may not be the pressure at the compressor outlet side due to the IC. While the drop is small, it may still be enough to create a differential.

If the turbo is simply moving air at the same rate as the engine is consuming air, with the excess being vented via the valve during these low load, constant pressure conditions, the turbo would produce less back pressure on the exhaust. Again, my only concern is contamination of the intake. While the valve opening is certainly not large and there is exhausting air, I'm wondering if the volume is enough to provide an adequate shield in these rare, but possible conditions. The majority of my driving by far does not allow for the throttle to be regulated such that boost /vacuum is 0, this typically only occurs on the highway cruising in 6th while going up a moderate hill. Otherwise on flat ground we have a constant vacuum of about 22 inHg or we are making boost > 1 psi.

 

[TheLion]

Had an idea for a good filter media. I am only concerned about water vapor and large particles that might have the velocity and mass to enter the air barrier during extended low pressure venting, so we don't need a paper media type filter (although it wouldn't hurt to have one if anyone knows of one that would fit).

http://www.ebay.com/itm/Pre-Filter-...ash=item5b0f725b17:g:uhAAAOSwAvJW91tZ&vxp=mtr

Outerwear pre-filter media is a very fine mesh, it will stop anything that is sand sized particulates as well as repels water. Combine that with the low positive pressure and the fact that the coolant tank pumpkin sits right in front of the BOV, it would really take an act of God to cause contamination.

Honestly the low hissing doesn't bother me, so that's not the concern, I can't even heart it when the windows are rolled up, especially on the highway, so I'm only coming back to the contamination possibility. It's cheap and commonly available, works well on K&N type filters for screening out water and larger particles and even some larger dust particles.

Small dust particles can be repelled by positive air pressure, in fact it is a standard requirement for safety of electrical enclosures in hazardous areas, to use a low positive pressure of at least 0.2in H20 minimum to prevent ingress of explosive gasses and dust.

However I think the filter screen is more merited in this instance of automotive application due to the fact that particulates are not free floating in the air, but traveling at velocity so some added protection is in order.

 

[rl16v6]

Installed my Boost Operated Blow Off Valve today. I took it out for a drive and it feels like it revs more freely and generally feels smoother.

Installation was easy and straightforward, no codes, so far so good! Thanks Boomba for a great product.

Tough to see after installation, but here's a couple of pics!

 

[TheLion]

Installed my Boost Operated Blow Off Valve today. I took it out for a drive and it feels like it revs more freely and generally feels smoother.

Installation was easy and straightforward, no codes, so far so good! Thanks Boomba for a great product.

Tough to see after installation, but here's a couple of pics!

I noticed a similar feeling, but I would say for me I felt like it would build boost earlier on, I think it's a great investment for the price. Again my only concern is contamination during the low boost / no boost continuous venting, which has nothing to do with Boomba, but is a normal PCM function. However their valve is not filtered so it's a bit of a concern. I have an outerwears cover on order and well see if that holds up to the hot air vented (it's rated for up to 450F).

 

[rl16v6]

I noticed a similar feeling, but I would say for me I felt like it would build boost earlier on, I think it's a great investment for the price. Again my only concern is contamination during the low boost / no boost continuous venting, which has nothing to do with Boomba, but is a normal PCM function. However their valve is not filtered so it's a bit of a concern. I have an outerwears cover on order and well see if that holds up to the hot air vented (it's rated for up to 450F).

I appreciate your concern about the lack of a filter. I'm interested to see how you cover the BOV with the outerwears and your impressions.

 

[Woodshop77]

You could easily bag it like they do on the air filters of off road vehicles. Concern of course would be heat. (Or wrap it with heat resistant foam)
I'm running the Boomba BOV and I hear the hiss but I talked to my mechanic earlier and found that it was ECU related, so I haven't been too concerned I am so far having better success with this product than the mechanical BOV I had on the car. I experienced a drop in MPG when I went to the mechanical BOV and it has returned in small part to the new unit. I will jump to Boomba's Recirc BOV if they choose to make one. The vehicle NHV seemed to pick up with the install of this unit , VTA and such, and I'm too old to deal with it sounding like a F&F car.

 

[Juben]

That hissing is super annoying at times. I've been running mine recirculated and it's perfect to me. I can still hear all the great turbo spooling noises, but I don't get people looking at me like I'm driving a Honda when the BPV goes off, lol.

 

[Woodshop77]

Juben I hear ya, If I wanted a Honda covered in a Mustang Suit, I would have just gone out and bought a Honda. I like my mustang and everything it stands for! But I will go to a Boomba recirc unit asap if it happens! LOL

 

[TheLion]

I think it depends on where you live and their perception. There's a bunch of baby boomer's generation that liken my 2016 to the SVO of the 80's, so they know the past of the turbo stang. I haven't had anyone say it sounds like a honda, but honestly it's what you as the car owner care about (if you care about other people's opinions then maybe that would matter, otherwise you might care less).

I actually like the hissing, for me it's just part of owning a turbo charged vehicle. I suppose I woldn't be opposed to upgrading the valve in the future if I ever get sick of it, but with the windows up I can barely hear it.

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