CTSC only giving me 3 PSI

[junior40er]

I just instead my aem boost gauge and took my car for a soon last night and it was only giving 3 psi. This is really dissapointing and hoping to fix soon. Car drives great and no funny idles.

What I did last night:
1) loosened the belt a little, no change.
2)tightened the belt and no change.

Possibilities:
1) boost leak? If so what are common leak locations on the ctsc?
2) bypass valve? Wouldn't I get funny if that wasn't working?
3) altitude here 2900 feet? Can that impact my boost that much?
4) bad AEM boost sensor
5) I did cut and soldered my sensor to extend. Maybe bad solder causing some voltage drop and thus lower reading?

 

[funkynsx]

How does it feel when you drive it?
Are you feeling a drop in power?
If your running 3psi you would definently feel a power loss.
If not, it sounds like your sensors are reading incorrectly.

 

[E-Nough Logic]

What EMS are you on? You can check what the ECU is reading and see if its different.

 

[Aaron94T]

My guess is you need to tighten the belt more. I was getting 3-4 psi due to belt slippage. Did you notice less boost when you loosed it? Is it a gator belt?

 

[goldNSX]

How many miles on the unit? The last one who had low pressure found out that it was the unit itself.

 

[junior40er]

How does it feel when you drive it?
Are you feeling a drop in power?
If your running 3psi you would definently feel a power loss.
If not, it sounds like your sensors are reading incorrectly.

I have had it on for few months already but just put in boost gauge and AFR wideband gauge/sensor. It feels same as it always has but maybe it was like this the whole time?

What EMS are you on? You can check what the ECU is reading and see if its different.

No EMS.

How many miles on the unit? The last one who had low pressure found out that it was the unit itself.

4,500 miles from previous owner, about 800 miles with me.

 

[junior40er]

My guess is you need to tighten the belt more. I was getting 3-4 psi due to belt slippage. Did you notice less boost when you loosed it? Is it a gator belt?

Seems if I tighten it more it will be tighter than recomended. I have the gator belt which is supposed to have good grip without too much tension.

When I loosened it last night it was about 2-3 PSI. I went the other way and tightened it instead and its about the same but more solid 3 psi instead of 2-3.

 

[goldNSX]

Did you install it yourself?

 

[ScienceofSpeed]

Confirm with a mechanical gauge. If it shows the same pressure, the two most likely causes would be the belt slipping (you should see dust building up around the pulleys) or the bypass valve stuck open / leaking.

-- Chris

 

[junior40er]

Did you install it yourself?

Yes I did. I quadruppled checked every step and made sure I wouldnt have to do it twice.

are you running rich then? Is your AFR in the 10-11s?

No really. I cant remember exactly but I think it was in the 11's or 12's on WOT. 14.8-15 on idle.

Confirm with a mechanical gauge. If it shows the same pressure, the two most likely causes would be the belt slipping (you should see dust building up around the pulleys) or the bypass valve stuck open / leaking.

-- Chris

If I hook up a mechanical gauge then I guess it has to go on a dyno since I cant monitor it while driving? I hope its not bypass valve because I would then have to remove blower which sucks. wouldnt it idle weird if that was the case? I dont see dust on my belt and gator belt shows no wear on contact side.

 

[ScienceofSpeed]

If I hook up a mechanical gauge then I guess it has to go on a dyno since I cant monitor it while driving? I hope its not bypass valve because I would then have to remove blower which sucks. wouldnt it idle weird if that was the case? I dont see dust on my belt and gator belt shows no wear on contact side.

You would simply use a long hose to place it in the cabin as you drive (and have someone watch the gauge).

 

[SuperSonic]

When did you test it? You like in the high desert at 95 degree weather. When me and les drove big bear it was massive hot one time. Only boosted 2-3. Then got down to beach and hit solid 5. In the same day, 2-3 then 5 based on weather.

 

[junior40er]

You would simply use a long hose to place it in the cabin as you drive (and have someone watch the gauge).

Not a bad idea at all. I will look into finding a adapter to tap into my supercharger and a mechanical gauge.

When did you test it? You like in the high desert at 95 degree weather. When me and les drove big bear it was massive hot one time. Only boosted 2-3. Then got down to beach and hit solid 5. In the same day, 2-3 then 5 based on weather.

It was at 1am so temp wasnt an issue. I'm almost 3K feet ASL but I doubt it will cause a 2-3PSI loss, would it?

 

[cptnsx]

Not a bad idea at all. I will look into finding a adapter to tap into my supercharger and a mechanical gauge.




It was at 1am so temp wasnt an issue. I'm almost 3K feet ASL but I doubt it will cause a 2-3PSI loss, would it?

Your altitude should cost you around 1.5 psi no matter the temp. Air density is also affected by temp and humidity so that could cost you .5 psi (or give you .5 psi if its really cold and dry). Plus the reading may be off 1 psi (in the margin of error). Giving you a loss of 2 to 3 psi.

Which version of the Comptech do you have. The older ones did not hit 6 psi consistently anyway.

Also if you can log the psi as you do a full throttle pull you should see if you are slipping. Slipping typically occurs in the upper rpm range and you will see that. These belts can stretch and you can't tell except by seeing the boost fall off in the upper rpm range. When that happens you must replace the belt.

 

[Aaron94T]

You would simply use a long hose to place it in the cabin as you drive (and have someone watch the gauge).

+1, I did this when I had my low boost issue. I just ran the hose into the drivers window and held it in my left hand as I drove. Only took 1 second of WOT to verify the boost.

I still vote for loose belt. Do the allen heads on the SCer pulley have grey dust on them?

 

[Blacknot]

If you can twist the belt from the alternator to the crank pulley more than 1/2 way its too loose. You always want to check the belt on the longest section. When my belt was too loose my CTSC was pulling 3-4lbs. If its not the belt it could be the hose clamp right by the bypass valve keeping it from closing fully. If that is the issue then you have to pull off the charger

 

[junior40er]

Don't think its slipping since psi doesn't fall off at high rpm. I just tightened the belt even more and still 3 psi. There was dust on my pulley Allen heads so I was hoping it was slippage but after tightening the belt there was no change.

 

[RYU]

Steps you need to take... and us "guessing" isn't one of them.

1. Rule out a bad gauge. Go find a mechanical boost gauge for $30 from Autozone or something. Plug it directly into the manifold. Don't T-off some existing boost line since, for all you know, that line is leaking too.

2. Slipping belt - Sounds like you ruled this out but grease on any of the pulleys is something to look for. Feel your belt for excessive heat. If it's really hot then you have slippage.

3. Tighten all the fittings that you see that may cause a boost leak. Put thread sealer on any fitting that might be suspect.

4. Retorque all bolts that you have access to from the intake manifold up thru to the blower itself. A leak can come from anywhere after the blower and into the heads.

5. Replace all the vacuum lines that you can reach. I once had a cracked vacuum line that you would never have known was cracked until you actually bent the thing.

6. Zip tie all vacuum hose fittings to ensure a proper seal.

7. If you still have a leak, I'm sorry... you'll have to pull off the blower and check the bypass valve. Perhaps there's something causing it to crack open.

8. Once you've got the thing off.. you might as well redo everything from the beginning while replacing/fixing all possible leak sources. You'll need plenty of gasket maker (don't know what they're called), new vacuum hoses, that white pipe thread stuff, etc...

9. After getting everything back together and you're still down 3psi (You should be at 6lbs solid) then time to go shopping for a new blower.

On a side note:
Getting a datalogger like a Zeitronix unit below will save you some time. I've plotted data points during a 2nd gear pull to make it easier to read. My max boost at sea level is a solid 7lbs but this was at 6000ft in the canyons and I rarely get over 5.5-6lbs up there. So a drop of 1.5psi, as someone said, is accurate (not 3lbs). You can see below that this was a 2nd gear to 3rd gear pull. In 2nd gear at 100% throttle, from 5300 rpm to 6700 rpm, boost increased from 5.1 to a consistent 5.5lbs until I shifted to 3rd gear. Then it stays solid again at 5.5lbs.

Yes, I know my AFR is a bit rich and i'm running a tad hot in my IAT but that's a different story.

 

[junior40er]

Thanks man. I will check everything you said. I took a peak on the aluminum pipe under blower and looks like I may have a crooked clamp maybe no sealing the coupler completely to hit 6 psi? I will try to get a pic but its in there.

What vacuum lines can cause its to not hit full boost?

 

[RYU]

Thanks man. I will check everything you said. I took a peak on the aluminum pipe under blower and looks like I may have a crooked clamp maybe no sealing the coupler completely to hit 6 psi? I will try to get a pic but its in there.

A leaking elbow will not be the source of your boost leak. Any air that goes thru that pipe has already been "relieved" from the blower by the bypass valve. That valve is open when it sees vacuum. In other words, when in boost that valve should closed.

What vacuum lines can cause its to not hit full boost?

Whatever lines come out of the intake manifold. There's lots of them...

found a pic online of the underside. there's no access to this unless you uninstall the manifold.

 

[junior40er]

Damn, so there goes that then. Saw your post after I pulled it off hose to loosen up clamp and try and re tighten while on car which sucked cause I had to remove CT strut bar which sucks.

Regan, do you think if I truly had a boost leak the car would run so good (as in no idle issues and the little boost I have being stable)?

I'm hoping its boost gauge (remember, I cut wire and extended it with solder so maybe bad/low feedback signal?).

I will put it back tomorow and try and see if I can get a mechanical gauge and nipple to tap in charger and test. If that still shows 3 PSI I will remove and inspect (after calcoastal drive). If it shows 5-6 PSI then I know its my boost gauge and will resolder connection.

 

[RYU]

I really hate guessing but a leaky boost will not cause your idle to be poor. What may cause your idle to be poor is a vacuum leak. A boost leak doesn't always mean a vacuum leak as well. I suppose a leaky bypass tube will cause your car to idle poorly but that doesn't seem to be your problem either.

With your stock CTSC fueling povisions, your boost-a-pump sees positive boost pressure regardless of you're actual boost level. It simply bumps up your fuel pump voltage regardless if you're at 3lbs or 6lbs. It's why I initially thought you'd be running rich but I guess the RRFPR is compensating appropriately for the varying boost pressure.

Long story short.. I don't have a guess for what's wrong with your setup. I do have a methodology to track it down I suppose.

I suspect you'll be ok driving the car at 3lbs. Just keep an eye on that AFR.

 

[junior40er]

OK, so I looked some more and notice vaccuum line#3 coming from the throttle body is capped off as it should be according to CTSC manual but I noticed the vaccum cap is very cracked. Im replacing this anyways tomorow but can that cause a limited boost issue?

 

[junior40er]

I really hate guessing but a leaky boost will not cause your idle to be poor. What may cause your idle to be poor is a vacuum leak. A boost leak doesn't always mean a vacuum leak as well. I suppose a leaky bypass tube will cause your car to idle poorly but that doesn't seem to be your problem either.

With your stock CTSC fueling povisions, your boost-a-pump sees positive boost pressure regardless of you're actual boost level. It simply bumps up your fuel pump voltage regardless if you're at 3lbs or 6lbs. It's why I initially thought you'd be running rich but I guess the RRFPR is compensating appropriately for the varying boost pressure.

Long story short.. I don't have a guess for what's wrong with your setup. I do have a methodology to track it down I suppose.

I suspect you'll be ok driving the car at 3lbs. Just keep an eye on that AFR.

Same here, I dont like guessing so im just checking all lines and get a mechanical gauge. I ran car today and it was in the mid-high 11's AFR at WOT.

 

[junior40er]

So I picked up a mechanical gauge from autozone, fitting and hose and hooked it up. I did a few runs and it gave me a solid 4 PSI, no more and no less. WTF. I mean, thats better and I dont know if I should believe the 3 PSI on my digital AEM or the 4 PSI on mechanical gauge.

If mechanical gauge is correct then its something I can live with and assume I have another .5-1 PSI when at sea level.

For now I will leave it as it and after the calcoastal drive I will remove CTSC and inspect for any leaks.

PS: idle AFR is high 14's while WOT is high 11's....is that normal?