low boost help

[bigbirdSCed]

sup guys,

so ive been monitering my boost gauge lately(more then usual) because its new and glows red . but ive noticed it will only read about 2 psi. it reads 2 at WOT and in ANY gear or rpm. it wont go any higher. the car also feels a little down on power(walked a near stock 90's maxima auto ).

now, i think i know the problem but i wanted to confirm my suspicions with yall. i have had several bad cat codes(catylists below threshold) just the single codes and they come on after long drives, spirited or not.

i was thinking that the decrease in performance was the cat(OEM and origional) goin bad but i didnt think it would have anything to do with the boost. after a quick search i saw a couple comments about how a blocked cat was causing lower boost numbers. is this an accurate connection to make? if so this seals the deal and the cat goes asafp. if not id liek advice on other things to check.

the gauge is ok...brand new and has no kinks(that i could find). it finctions perfectly up to 2 psi. i have checked the vaccume lines for leaks but didnt find any. any advice woudl be great.

Bird

[akora12]

What are the codes you're throwing? Not sure about a blocked cat problem, but I do know the "cat below threshold" CEL can be false at times due to running rich. I threw a couple a few years ago and have never had them pop back up again. I assume your cat is a bit older than mine, though.

[JavaJoe_2]

Wouldn't the boost be higher because the cat prevents exhaust from exiting?

[Dawgz]

Wouldn't the boost be higher because the cat prevents exhaust from exiting?

I remember when my precats were cloged (when i was on a cali spec system)...my boost gauge was reading real low (this was when i was on 4psi).

[bigbirdSCed]

i think you were one of the ones who i saw mention that. im pretty sure its running rich. the car currently has no tune, just a 190lph pump...so the codes may be just that. but shes still down on power. hopefully the code pops back up soon and i can write it down. but im near 100% sure thats the code it was.

[Akfahad]

^^personally, I would just swap out the cat anyways with a high flow one regardless. you already know its bad and its only going to help you, so why not just swap it out (sounds like it might fix your problem too).

[trd4life]

swap out the cat for sure.

[Eye8Pussies]

swap out the cat regardless


but in general, a stuffed cat will should actually not affect boost, and will make boost build FASTER, as it creates more load on the motor.


But regardless....a good way to check if your cat is clogged....at idle, when you rev the motor, does your supercharger whine? because if there is no load, it shouldn't. if it does whine, then it means that your cat is clogged and the back pressure of it is creating load when there shouldn't be.

learned that trick from tony

[bigbirdSCed]

definatly replacing the cat. and king thats a great little trick. it does do that. i always thought it was funny how the SC on this car would have more whine when reved then the gen 4 did(high flow cat installed).

so then what do yall suggest i check to track down my low boost problems? i want to check out the actuator but im not sure what im looking for.

[RON]

sup guys,

so ive been monitering my boost gauge lately(more then usual) because its new and glows red . but ive noticed it will only read about 2 psi. it reads 2 at WOT and in ANY gear or rpm. it wont go any higher. the car also feels a little down on power(walked a near stock 90's maxima auto ).

now, i think i know the problem but i wanted to confirm my suspicions with yall. i have had several bad cat codes(catylists below threshold) just the single codes and they come on after long drives, spirited or not.

i was thinking that the decrease in performance was the cat(OEM and origional) goin bad but i didnt think it would have anything to do with the boost. after a quick search i saw a couple comments about how a blocked cat was causing lower boost numbers. is this an accurate connection to make? if so this seals the deal and the cat goes asafp. if not id liek advice on other things to check.

the gauge is ok...brand new and has no kinks(that i could find). it finctions perfectly up to 2 psi. i have checked the vaccume lines for leaks but didnt find any. any advice woudl be great.

Bird

Might want to check the vacuum hose that actuates the bypass and the operation itself. The control unit remains closed under vacuum.. when not under load (most of the time). Under load the vacuum is released and the valve/plate SHUTS, allowing boost. Also, if it doesn't close completely your losing boost HUGE.


Link:

http://www.magnusonproducts.com/bypass.htm



Why use a bypass valve?
The best-kept secret in forced induction is the little-known bypass valve. This small valve, when properly installed between the supercharger and the air throttle body, allows the supercharger to become extremely efficient in terms of economy and parasitic power loss. Our MP90 supercharger uses less than 1/3 of 1 HP while cruising at 60 MPH. A vacuum actuator control unit that is normally closed operates the bypass. When boost is required (i.e., under acceleration) the vacuum is decreased and the bypass valve instantly closes, causing pressure to increase into the cylinders. This equalized vacuum condition virtually eliminates the normal parasitic power loss of a forced induction system

[GreeKAvaLoN]

i'm not sure about this or not, but i did a lot of research on the one way valve cause i'm trying to figure out why and how badly it was needed and a lot of people said it can cause boost leaks. maybe urs is doing that? is the valve stuck? maybe the boost gauge is broken and wont pass 2?