i think the scb actuator is bad (NOW WITH PICS)

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icnuthin
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i think the scb actuator is bad (NOW WITH PICS)

Post by icnuthin »

so after installing s/c, then fixing all the leaks, then replacing a distributor(which went bad) the car is running good. except the vacuum being at 12in... before i put it on the scb actuator was hard to move. but now it stays full open at idle then when i close it by hand my vacuum goes up to 16-18in. with the car off it closes.. it feels too easy to move with the car running..
im tuned by nistune and every thing looks right. (fuel and timing map)

now for the test run. i floored it and i went straight to 0psi and the s/c is whining.
no boost at all :(

should i purchase a new actuator?
Last edited by icnuthin on Sat Nov 27, 2010 2:11 pm, edited 1 time in total.
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Re: i think the scb actuator is bad

Post by klattr1 »

icnuthin wrote:so after installing s/c, then fixing all the leaks, then replacing a distributor(which went bad) the car is running good. except the vacuum being at 12in... before i put it on the scb actuator was hard to move. but now it stays full open at idle then when i close it by hand my vacuum goes up to 16-18in. with the car off it closes.. it feels too easy to move with the car running..
Yeah that vacuum is low...i create somewhere around 18-20 inHg vacuum at 800 rpm idle speed. Your vacuum shouldn't bee that low unless you had some sick cams in your setup. What source are connecting the hose on the bypass valve/actuator to? somewhere between the throttle body and the supercharger inlet? Find a copy of the Xterra FSM to see how the actuator should open/close at different vacuum levels.
icnuthin wrote:now for the test run. i floored it and i went straight to 0psi and the s/c is whining.
it's supposed to whine :D
j/k, even if the actuator/bypass valve was open all the time, you should still see some boost (2-4 psi depending on setup)

Let's see a picture of what the running setup looks like so far.

EDIT, I just noticed your other thread...please don't make new threads when the issue is the same as another thread...in the future, just update the old ones and people can give feedback in it.
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Post by icnuthin »

yea sorry about the other post but im freaking out,

but i do notice that the valve does close when throttled.
it is so easy to move at idle. its also set to 900rpm

at first i had a hose out of the adapt. plate T to the fpr and the scb valve. and then i just took it off and left the valve open air and closed the vacuum line but i left the small one that goes to the s.c on...

im prob gonna take it off again and go over the plate to sc gasket but first another boost leak test for the 8th time.
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Post by 240cp »

What nipple on the actuator do you have the vac line hooked to? When i was messin with superchargers my supercharger didnt come with any of the vac lines and i mistakenly hooked the vacuum line to the wrong nipple and i would get boost at idle and none at throttle. My prob was i was using the the overboost part of the bypass actuator instead of the resirc part. Hope that was clear. Anyways, check the actuator and make sure your using the lower nipple instead of the upper and take your vacuum from the supercharger intake to the lower nipple on the actuator.
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Post by icnuthin »

240cp wrote:What nipple on the actuator do you have the vac line hooked to? When i was messin with superchargers my supercharger didnt come with any of the vac lines and i mistakenly hooked the vacuum line to the wrong nipple and i would get boost at idle and none at throttle. My prob was i was using the the overboost part of the bypass actuator instead of the resirc part. Hope that was clear. Anyways, check the actuator and make sure your using the lower nipple instead of the upper and take your vacuum from the supercharger intake to the lower nipple on the actuator.
well when i got it there was one on it that was from the supercharger to the actuator..very short line, then i hooked up the vacuum to the other that was open then tried it without the vacuum but leaving the small line on. still nothing on both. i think the sc is bad.
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Post by 240cp »

You should not be able to move the actuator when the car is idling. 18-20 in hg is alot. The way you have it hooked up, small line to supercharger is correct. Do not hook up the other nipple unless you have a boost solenoid set at 10 psi like nissan did it. If your still not seeing boost replace the actuator. I think i have one ill send if you pay shipping.
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Post by icnuthin »

240cp wrote:You should not be able to move the actuator when the car is idling. 18-20 in hg is alot. The way you have it hooked up, small line to supercharger is correct. Do not hook up the other nipple unless you have a boost solenoid set at 10 psi like nissan did it. If your still not seeing boost replace the actuator. I think i have one ill send if you pay shipping.
sure ill pay. ill do that before i buy a whole new s/c.
im gonna take pics up close so yall can see my progress. and i still have stuff to do like fuel lines wrapping.

im still trying to see what i wanna do for cooling. im leaning towards WMI. but also cryo2 bulb intake cooler and fuel cooler but i dont know how long co2 will last or how much it uses
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Post by adamky »

Yeah, post up some pics. This whole things sounds very strange. I don't understand why your vacuum is so low, and why it would increase if you close the bypass valve...? It just doesn't make any sense. Are you sure you don't have any vacuum leaks? Did you connect the correct port on the supercharger to your brake booster vacuum line? And you're only running the short vacuum line on the bottom of the bypass actuator, correct? The other port is not hooked to anything?
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Post by icnuthin »

adamky wrote:Yeah, post up some pics. This whole things sounds very strange. I don't understand why your vacuum is so low, and why it would increase if you close the bypass valve...? It just doesn't make any sense. Are you sure you don't have any vacuum leaks? Did you connect the correct port on the supercharger to your brake booster vacuum line? And you're only running the short vacuum line on the bottom of the bypass actuator, correct? The other port is not hooked to anything?
correct, not hooked to anything.
ill get pics tonight my internet was down last night.
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Post by adamky »

Does your brake booster vacuum line go to the port at the back of the supercharger, on the side closest to the block?
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Post by icnuthin »

adamky wrote:Does your brake booster vacuum line go to the port at the back of the supercharger, on the side closest to the block?
yes it does.. im gonna post pics tonight when i get home.
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Post by icnuthin »

my engine bay
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my iiac aac lines
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belt routing
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my vac lines simplified
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i assure you that the bottom line is on and the big break line is on the sc
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the only line coming out to the adapter plate is going to the fpr. the other line on the t is closed
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Post by adamky »

The T in the brake booster vacuum line... what is that for? Is that where you are getting the boost signal from, because that's what it looks like. If so, there's your problem, or at least, part of your problem. That line will never see boost. You need to T into the line going from the supercharger plate to the FPR. That line will see boost and vacuum, so this is where you need to get your boost signal from. The brake booster line shouldn't have any T's in it at all. It should go from the back of the supercharger, directly to the brake booster.

I can't see where everything goes, but that's what it looks like to me. Everything else, like your AAC/IACV setup looks fine.
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Post by icnuthin »

adamky wrote:The T in the brake booster vacuum line... what is that for? Is that where you are getting the boost signal from, because that's what it looks like. If so, there's your problem, or at least, part of your problem. That line will never see boost. You need to T into the line going from the supercharger plate to the FPR. That line will see boost and vacuum, so this is where you need to get your boost signal from. The brake booster line shouldn't have any T's in it at all. It should go from the back of the supercharger, directly to the brake booster.

I can't see where everything goes, but that's what it looks like to me. Everything else, like your AAC/IACV setup looks fine.
the t is to my boost gauge. the one coming out of my sc is going to the fpr and i had it on the nipple of the scbv at first then i took it off and got same results.
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Post by adamky »

I don't think you understand what I'm saying. You're not seeing boost right now because you have the boost gauge hooked up wrong. Neither the brake booster line, nor the small line going to the scbv actuator will ever see boost. The ONLY line that will see boost is the line that goes from the top of the supercharger adapter plate to the fuel pressure regulator. If you're not reading your boost signal from here, your gauge will never show boost.

You may have other issues going on. It's hard to tell from just pics and a description. But from those pics, I can tell you with 100% certainty that you have the boost gauge hooked up wrong.
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Post by icnuthin »

thanks i understand. i was sold a bad supercharger. if i wiggle the pully back and forth the runners are hitting each other. there are marks and lines from them smashing together. my friend who is a nissan tech/manager came over and looked at it.
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Post by turbonola »

adamky wrote:I don't think you understand what I'm saying. You're not seeing boost right now because you have the boost gauge hooked up wrong. Neither the brake booster line, nor the small line going to the scbv actuator will ever see boost. The ONLY line that will see boost is the line that goes from the top of the supercharger adapter plate to the fuel pressure regulator. If you're not reading your boost signal from here, your gauge will never show boost.

You may have other issues going on. It's hard to tell from just pics and a description. But from those pics, I can tell you with 100% certainty that you have the boost gauge hooked up wrong.
ok, is that just for s/c setups because if thats the fact i told him to do it that way because thats where i have my boost gauge hooked up. if you are saying the brake booster never see's boost you are right. it never sees boost because of the checkvalve in line. other than that he should be seeing boost from what i'm seeing. do you mean that he shouldnt even use the port that he's using? i dont understand? help me understand s/c's more.
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Post by adamky »

Yes, it is different for a turbo setup. In a turbo setup, your brake booster line will see boost because the entire intake manifold gets pressurized. I know many turbo folks use a vacuum block on the brake booster line and it works great for a boost gauge. But with a supercharger setup, the only part that sees boost is the upper intake runners, and the internal volume within the upper part of the supercharger itself (under the supercharger plate). All of the ports on the lower part of the supercharger, such as the one that goes to the scbv and brake booster, will never see boost because they are located on the intake side of the supercharger.

Right now, it looks like everything is connected correctly, except the T in the brake boost line needs to be removed, and the boost gauge signal needs to be T'd into the fpr line.

Sucks that the supercharger is bad. I figured there may have been other issues going on.
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Post by icnuthin »

yea it is what it is and im just gonna deal with it...i have another s.c with a bad snout bearing. everything else on it is good so im gonna fix that one.
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Post by timbo »

I sent you a text about the S/C unit. try and get me those numbers off it so i can get them to the guy i got the M62 from. I had none of these issues, all my issues were with the fuel pressure and injectors leaking. Also try send some pics of the rotors, I'd like to be able to show the guy the pics.
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Post by icnuthin »

sure ill try to get them in the casing but i might have to take them out to get a good pic
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Post by esahuque »

icnuthin wrote:sure ill try to get them in the casing but i might have to take them out to get a good pic
take a video of all the play in s/c
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Post by klattr1 »

hmm, it's hard to tell what's going on with your setup with all the million hoses running in and out...but from what I can tell, here are some suggestions:

Connect a hose directly from the supercharger actuator/bypass valve to the little bung/nipple on your intake pipe (between the throttle body and the supercharger inlet). This will keep the bypass valve open at idle and low load, but then as soon as you stab the throttle, it will close the butterfly and allow you to make max boost given with your setup. On my setup, this nets 18-19 inHg at idle and ~10 psi at wide open throttle.

Now if you are doing some initial tuning and want to keep the boost level low, connect a hose directly from the bypass valve/actuator to the 90 deg. nipple that's on the top of the supercharger plate (with it being tee'd with the fuel pressure reg. signal)...on my setup, this nets 18-19 inHg at idle and 3-4 psi in wide open throttle due to the butterfly being open all the time.

Resulting boost level/psi with this setup is all based on pulley size, belt configuration, if supercharger housing is ported, size of intake pipe, etc.
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Post by icnuthin »

klattr1 wrote:hmm, it's hard to tell what's going on with your setup with all the million hoses running in and out...but from what I can tell, here are some suggestions:

Connect a hose directly from the supercharger actuator/bypass valve to the little bung/nipple on your intake pipe (between the throttle body and the supercharger inlet). This will keep the bypass valve open at idle and low load, but then as soon as you stab the throttle, it will close the butterfly and allow you to make max boost given with your setup. On my setup, this nets 18-19 inHg at idle and ~10 psi at wide open throttle.

Now if you are doing some initial tuning and want to keep the boost level low, connect a hose directly from the bypass valve/actuator to the 90 deg. nipple that's on the top of the supercharger plate (with it being tee'd with the fuel pressure reg. signal)...on my setup, this nets 18-19 inHg at idle and 3-4 psi in wide open throttle due to the butterfly being open all the time.

Resulting boost level/psi with this setup is all based on pulley size, belt configuration, if supercharger housing is ported, size of intake pipe, etc.
ok now im getting somewhere on knowledge thanks to you and adamky.
1. my boost gauge is hooked up wrong. i need to t off of the plate
2. where i had my vac line for the bv was coming from that plate so i was only seeing 3-4 psi and that would explain the im not feeling boost feeling.
makes so much sense. but the only thing im still having an issue is the idle not being at 18-19 inhg.
so im gonna try the other s/c i have
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Post by icnuthin »

quick update. i fixed my car back to NA for a bit to get my s/c fixed or get another.
i was 1 tooth off on both cams.. which screwed up my vacuum and then wouldnt start...
its all fixed now. and runs better than it ever did
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Post by esahuque »

icnuthin wrote:quick update. i fixed my car back to NA for a bit to get my s/c fixed or get another.
i was 1 tooth off on both cams.. which screwed up my vacuum and then wouldnt start...
its all fixed now. and runs better than it ever did
Good Job!
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Re:

Post by bmaz121 »

icnuthin wrote:
klattr1 wrote:hmm, it's hard to tell what's going on with your setup with all the million hoses running in and out...but from what I can tell, here are some suggestions:

Connect a hose directly from the supercharger actuator/bypass valve to the little bung/nipple on your intake pipe (between the throttle body and the supercharger inlet). This will keep the bypass valve open at idle and low load, but then as soon as you stab the throttle, it will close the butterfly and allow you to make max boost given with your setup. On my setup, this nets 18-19 inHg at idle and ~10 psi at wide open throttle.

Now if you are doing some initial tuning and want to keep the boost level low, connect a hose directly from the bypass valve/actuator to the 90 deg. nipple that's on the top of the supercharger plate (with it being tee'd with the fuel pressure reg. signal)...on my setup, this nets 18-19 inHg at idle and 3-4 psi in wide open throttle due to the butterfly being open all the time.

Resulting boost level/psi with this setup is all based on pulley size, belt configuration, if supercharger housing is ported, size of intake pipe, etc.
ok now im getting somewhere on knowledge thanks to you and adamky.
1. my boost gauge is hooked up wrong. i need to t off of the plate
2. where i had my vac line for the bv was coming from that plate so i was only seeing 3-4 psi and that would explain the im not feeling boost feeling.
makes so much sense. but the only thing im still having an issue is the idle not being at 18-19 inhg.
so I'm gonna try the other s/c i have
Happy SC days!
Well I hope you guys are still around. I don't know why everything I look up lately is 4 or 5 years old. What's with that? Anyway, if you have a min. I have a M62 4th gen 2001 Frontier supercharger factory installed. I put a vacuum pump to the lower actuator nipple and pumping to 10 it slowly leaks vacuum. If I open the the actuator by hand it leaks a lot. so is it bad? The upper one does not leak. on this one I can't tell when the valve is closed. Is that when the actuator is down or up? The small vacuum line (lower) runs to the SCB solenoid. The upper one is short and runs to the top back of the SC 5" or so. So I don't know if the top one closes the SCB or opens it?
If the leaking is bad then where can I get one?
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