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Discussion Starter · #1 ·
I installed the Agency Supercharger kit. I've had a problem producing the 5-7 lbs of boost they claim it will make. I get about 2-3 lbs at wide open throttle. Agency has sent me out 3 boost control solenoids and a couple of stiffer waste gate springs. Nothing fixed the problem. Long story short, I've been trying to test the boost solenoids to make sure there's nothing wrong with them.

This is what I've tried so far, based on info I found online:

So I disconnected the vacuum lines that go to the bypass valve and throttle bodies, but I left the lines connected to the solenoid so I could blow into them. I put the key to ACC, with no throttle applied, I can blow thru the bypass valve line and it will come out of the throttle body line, and vice versa. When I apply slight pressure to the gas pedal I hear the solenoid click and I can no longer blow thru the throttle body line and when I blow thru the bypass valve line it comes out the vent line. All of this is correct. However, when I apply full pressure to the gas pedal simulating wide open throttle nothing changes, I can still only blow thru the bypass line and it will come out of the vent line. At WOT it should open back up and I should be able to blow thru the bypass or the throttle body lines or vice versa. How does the solenoid know to open back up at WOT? When I press the gas pedal to the floor the solenoid doesn't make another clicking noise like it does with just slight pressure. Am I testing this correctly? I'm thinking that the solenoid is dumping boost to vent/atmosphere instead of closing and allowing the boost to go into the motor? Any help at all would be appreciated. I'm getting very frustrated with this kit. I definitely should have spent a little more and went with the Turbo!
 

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Funny you should ask this question now, as I’m in the middle of building up another S/C based kit for my dads rig, and just threw a new boost solenoid on it and had this exact issue.

I just did a little quick research on the forum regarding throttle cable adjustment, and found this:

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So yes, it very likely could be cable adjustment. I’m going out to work on my fathers rig tonight, so I’ll try and remember to test this theory.

Here’s his rig: It’s been a fun little build.

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Discussion Starter · #5 ·
Thanks for the help! I ended up doing the zip tie mod that SXS Blog did to their YXZ to take the slack out of the gas pedal. I was hoping it would tighten up the slack on the cable and open up the butterflies a little more. I tested the solenoid again afterwards and it was operating correctly at WOT. I used a thicker zip tie at first and the throttle response was immediate but at WOT the power dropped off bad like it was getting too much air (I should've kept an eye on the AFRs). I put a thinner zip tie in and the solenoid still operates correctly and the power doesn't drop off as bad at WOT. But it's still not running great and the throttle response isn't as good. After what you've told me I'm thinking about putting the thicker one back in and try adjusting the cable to try and fine tune it because the idle does tend to hang around 2500 rpms when I let off the gas.

But getting the solenoid to work correctly didn't solve the low boost problem unfortunately. Agency is sending me an even stiffer spring but I don't have high hopes of it working. I was looking into buying a smoke tester to check for leaks. I made a homemade smoke tester but it didn't work great.

Do you ever have problems with the throttle bodies coming loose? I see Weller sells upper and lower brackets for them.

Who makes the SC kit you're installing on your dad's machine? Packard? Looks 🤘. My cheap ass kit didn't come with an intercooler. Those charge tubes are twice the diameter of the tubes on mine lol. How much boost are you pushing?
 

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Do you do have your vacuum line hooked to the correct location? For S/C applications, I have always connected into the vacuum line that runs to the rear-most cylinder throttle body. It sounds likely you have already made sure that yours is correct, but just running through the possible issues. Also, if you aren't seeing boost at idle, then it is hooked to the right place!

Both the Packard and Agency units use the same cheap little AMR500 charger. I don't know what pulley size Agency uses with their kit, but the normal #1 wheel that comes on the Packard unit is approximately 2.81" in diameter. This pulley spins the charger at 95% of its max shaft speed at redline, so there isn't much room to grow there. We've machined down a Vortech pulley for the kit we are putting together for my dad. It measures 3.125" in diameter, which is exactly the same size as the #3 wheel that Packard previously sold, but is no longer available. This pulley will spin the unit at 106% of it's max shaft speed at redline, and I expect to only see around 6.5-7.5psi out of it. For reference, I generally saw 4-4.5 psi from my car when it had a Packard S/C on it and running the #1 (stock) wheel.

Elevation also plays a big role in what boost numbers you will see with a S/C. Whereas a turbo will simply spin faster, (only limited by efficiency), to achieve the same boost at elevation, a roots driven S/C unit will see the same drop-off that an NA car will due to less inherent atmospheric pressure. Anyways, if you are at elevation, then that could also be an explanation for the 2-3psi boost #'s.

The Packard units were notorious for having very problematic BOV's. I had one that was brand new and sent straight from them that didn't hold boost. Anyways, I don't know much about the BOV that Agency uses on their kit, but a leak would likely present with the symptoms you have described.

The kit we're putting together on my dad's unit is very much a home-brew setup. It uses the Packard intake, charger mount, and crank bolt, the aforementioned Vortech pulley, an intercooler that used to be on my turbo car from Push Turbo, and the same Agency Power plastic plenum that you have on your car, (I stole the Billet Packard one for my turbo setup).

We'll probably eventually just throw a basic turbo kit on it while re-using the liquid/air intercooler setup, but I fell into this S/C kit for the cost of buying my buddy a new rear diff, so I figured why not have some fun with it first.

Good luck getting your kit squared away. If nothing else works, then it might be worth trying a different BOV.

I get all my cold-side tubing/clamps and BOV parts from Intercooler Pipe Fabrication. If you decide to change anything up, then that is a good spot to source a BOV.
 

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For reference, this is what the basic Packard kit charge tubing looks like normally. And then below is the intercooler I built for mine back in the day when I had the S/C on my car.

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Discussion Starter · #8 ·
115931


This is where they have you T in the vacuum line. It's by the rear most TB. So I should be good there.

We're at about 750' elevation.

I think there's a good chance my problem might be the Bypass Valve like you were saying. If I pinch off the vacuum line coming out of it and take it for a slow ride boost will build to 5 lbs with the stock spring and 7 lbs with the stiffer spring. I wonder if the boost is getting past the packing that's around the piston inside the bypass valve. I don't know if that's a good way to test it or not. Maybe I'll just try another bypass valve. I'll check out that website for parts. Thanks.

Are you going to tune your dad's machine yourself? I wish I had the knowledge about this stuff like you. I love tinkering with things but this one has me frustrated.

Thanks again!
 

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View attachment 115931

This is where they have you T in the vacuum line. It's by the rear most TB. So I should be good there.

We're at about 750' elevation.

I think there's a good chance my problem might be the Bypass Valve like you were saying. If I pinch off the vacuum line coming out of it and take it for a slow ride boost will build to 5 lbs with the stock spring and 7 lbs with the stiffer spring. I wonder if the boost is getting past the packing that's around the piston inside the bypass valve. I don't know if that's a good way to test it or not. Maybe I'll just try another bypass valve. I'll check out that website for parts. Thanks.

Are you going to tune your dad's machine yourself? I wish I had the knowledge about this stuff like you. I love tinkering with things but this one has me frustrated.

Thanks again!
Haha, if you read through my build thread, and the S/C troubleshooting thread, you will see my knowledge is mostly gained from trail and error!

Yes, your vacuum line routing all looks correct. And also yes, if there is not a good seal inside the BOV piston it will subsequently leak boost, no matter how stiff a spring it has. Really, spring stiffness will not play much of a role in the WOT position, as boost pressure will be equalized on both sides of the BOV, so it should stay closed with nominal spring pressure. The spring pressure should really only be the deciding factor in the middle solenoid position, when it does not have equalizing boost pressure on the back side of BOV.

It might be worth engaging Agency Power to see if they might help you with direct BOV replacement. I was originally going to swap my dad's unit over to an aftermarket BOV, and just block-off the mount for the Packard billet BOV, but in doing so, would really be completely guessing about what spring tension to run. We may very well end up having to go this route if we end up ever having BOV leaking issues like the ones you are currently experiencing, but I'd say keep to the original BOV parts if at all possible. (Or sans being able to do that, find out what spring pressure Agency runs with their kit.)

Yes, I build my own tunes running a PCV-pti, and autotune. While its a relatively basic system, it works really well, (running the same setup at 20ish psi on my turbo car), and makes a night-and-day difference in how the machine runs vs. a flash and GEMS tuner. If you ever go this route, I'm happy to help you figure it out. There are also some great Dynojet PCV tutorials on Youtube that help get new users started. Also, if you ever do go this route, you can get away with only the normal PCV, (non pti version). This will only allow tuning by throttle position, vs. tuning by boost. I did not tune by boost when running the S/C on my car, and got it 90% good. I had one little section down low in the map right at solenoid switch-over that was very rich, and was never able to get it quite right, but got it close.

Alternatively, we are tuning my dad's car by both throttle position, AND pressure. This will be my first time creating a S/C tune in this method, but essentially, a boost map will be overlaid that will account for boost variation across throttle positions. (This is the primary way you have to tune turbo cars, as boost pressure is widely varied based on load. Not as much with a S/C car, but my theory is that I can get it perfect or almost perfect by tuning this way).

Finally, if you do go the PCV and autotune route, I highly recommend setting up autotune on a switch that allows you to manually turn it on and off as desired. Then only have it "on" when tuning, and only when applying at least some throttle.


I know that is all a lot, but with some trail and error and some research you will get there!
 

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The S/C tuned correctly can actually rip pretty well! Here is my car back when I had the Packard unit on it. 4ish PSI on stock 16 rods. I did have it intercooled, and built my own open intake, but that was all more for noise and cool factor than actual function.

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Discussion Starter · #11 ·
Wow! I didn't think you could pull up the front end with 4.5 lbs of boost 😳 I know it's easier with paddles but that's still impressive!

Thanks for the help again. I REALLY appreciate it! I'll let you know if I get it running right. 🤞
 

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When I had the Packard S/c on mine at 6800 ft I would only see 2-3psi at wide open throttle and at around 1100ft it was 3-4psi switching to turbo and ditching the sc was the greatest thing I did I have since went with a bigger turbo kit and stand-alone ecu
 

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I installed the Agency Supercharger kit. I've had a problem producing the 5-7 lbs of boost they claim it will make. I get about 2-3 lbs at wide open throttle. Agency has sent me out 3 boost control solenoids and a couple of stiffer waste gate springs. Nothing fixed the problem. Long story short, I've been trying to test the boost solenoids to make sure there's nothing wrong with them.
This is what I've tried so far, based on info I found online:
So I disconnected the vacuum lines that go to the bypass valve and throttle bodies, but I left the lines connected to the solenoid so I could blow into them. I put the key to ACC, with no throttle applied, I can blow thru the bypass valve line and it will come out of the throttle body line, and vice versa. When I apply slight pressure to the gas pedal I hear the solenoid click and I can no longer blow thru the throttle body line and when I blow thru the bypass valve line it comes out the vent line. All of this is correct. However, when I apply full pressure to the gas pedal simulating wide open throttle nothing changes, I can still only blow thru the bypass line and it will come out of the vent line. At WOT it should open back up and I should be able to blow thru the bypass or the throttle body lines or vice versa. How does the solenoid know to open back up at WOT? When I press the gas pedal to the floor the solenoid doesn't make another clicking noise like it does with just slight pressure. Am I testing this correctly? I'm thinking that the solenoid is dumping boost to vent/atmosphere instead of closing and allowing the boost to go into the motor? Any help at all would be appreciated. I'm getting very frustrated with this kit. I definitely should have spent a little more and went with the Turbo!
 

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Curious if anyone would be willing to share your AgencyPower (or other supercharger) ECU maps?

They don't seem to have anyone there anymore that can discuss it, and I don't think they actually loaded the proper map into my ECU.

I have experienced all of the issues listed above, and aside from proper tuning, I think things are functioning correctly. I am at 4700' and have about 4.5-5.5 lbs. boost consistently while cruising. At WOT, the boost falls off as it should. But I am a bit lean while cruising except in the lower RPMs. I think it didn't get flashed, so I now have an FTECU and would like to compare. (I also have the Alba aggressive CAMS and full exhaust)

Thanks in advance - beers on me!
 

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Who did you get the kit from? Vivid Racing offered to send me the Supercharger Map with the purchase, but I never committed to purchase for a couple reasons.

I was right about in your footsteps. When I spoke to Vivid Racing last year about the Agency Supercharger, they offered to send me the map as it uses FTecu. I already have a FTecu bike side kit and could do it myself. As a back up, I also purchased a Bazzaz Z-Fi and Z-AFM in the meantime for ported head and GYTR cam to accomdate the Graves map. It was my intent to add the supercharger, flash the Supercharger/FTecu map and hopefully get it fine tuned with the Bazzaz. That was my initial planned progression with the build.
 
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