Darksun

Its been consistantly 44 degrees out here on long island at night and I' just knowticed that my boost guage has been going up to just about the 15 psi line on the stock pulley. it almost touches it but no cigar, so of course i was like WTF!?!? and was like this is cool. So drove over to my friends house to let him see what I was talking about but then i started to notice the more i would make the car hit that boost the computer started to catch on and would bleed the boost off back to the 12.5 line near redline. The boost bleed off is more noticeable in third pulls but its keeps trying to hit the 15 mark on the stock pully. Than of course bam check engine light. Used my friends scanner and was throwing the code PO171. I did the welfare airbox mod so i figureg its a lean condition code. Im' guessing the only way to keep all that extra boost is to do that bypass mod but i did it once and wasn't to sure if the car was liking it or not. Gotta love that nice cold air at night, its like a free horsepower mod.

So, I was going to throw on this 3.0 pully but than i was thinking im almost hitting 15 on the stock pully and getting bleed off so throwing on a smaller pulley would probly net me no gains. Am I correct in this thinking? I would have to hold off on putting the pulley on anyway cause im' having some technical difficulties with the car right now i have to get taken care of at the dealer first.

Chevypowered

The smaller pully will increase you low end lorque and you need it if you want the stage kits. I just ordered my 3" pully. I got it because i'm only getting 6.5 LBS of boost. but you max boost will coem sooner if you have the 3"

selfinfliction

i'd take it to get checked out personally. if you're hitting 15psi with the oem pulley, something might be fubar'd

Eddie

if its cold out side cars will have the tendency to boost more. it is normal w/ boosted car's dont worry.

codyss

Quote: I did the welfare airbox mod


That is the funniest thing I have read all day. Never heard anyone put it like that before.

Darksun

Ha ha wanna here the funny thing my supercharger is making this werid werring nosie all in a sudden. I guess i should have mentioned that. What ever it is it doens't sound to great. Its kinda like what a after market Tb sounds like when its trying to seal after you let your foot off the gas pedal. not sure if that explains it good.

selfinfliction

it is normal for boosted cars to make a little bit more boost, but 16% increase because of a few degrees is huge amount considering the small volume our setups have, and the fact we're mechanically driven, and not a turbo.. turbos make alot more power in the cold weather

Woodio

I hope something didn't get in the intake when you were doing the mod and break the impellers.

Darksun

Alright guys help me figure this one out. First i was out side with my friend trying to figure out what motor mount had gone bad and saw that the front motor mount was shaking so bad you could move it with your hand. So thats one problem figured out, getting that fixed shouldn't be so bad. But than when im reving the car in neutral the car was hitting boost?!?. So i was like well its not suposed to do that. So i hold down the gas pedal and bounce it off the rev limiter and sure enough the car hits 15 psi in neutral every time. now I know that with the boost bypass mod you can hit boost in neutral but the thing is I don't have that mod on my car. My bypass still works just not too well Like its duming out or sumthing. if i stomp the gas in neatural it goes to 15 psi but if i flutter it first once than try the bypass catches it and it won't go outta vaccum. So if i punch the gas in second gear at 30 mph i hit 12.5 at 5000 rpms than it goes up to just touching the 15 psi line than i shift to third and the boost shoots up to 10.5 psi and than goes to 12.5 keeps going holds right before 15 psi line than at 6000 rpms bleeds off to 12.5 and holds 12.5 from 6000 till 6400 fuel cut. The only cool thing about that i can think even though the stock car can't do it is you can launch in boost already. Since my mount is already broken im in no mood to test out that theory to even see if it works out good but even if i tried with a working car im sure the wheel hop would smack me around thus cancelling out the effects of trying to launch in boost.

Now on to the fun part DTC codes. I first had the PO171 code that would turn it self off but than i noticed that the light had been on for two days stright so i just checked it and i have 4.
PO171
PPO103 <--This one is a MAF input high code i belive need some one to confirm that for me and also please explain it
and Two PO420 codes. <-- low cat effeicent i think please explain also.
Don't know how thats possible to throw the same code back to back twice but whatever.

So.........Any help or input would be greatly apreciated.

Cobalt_Supercharged

If I remember right the PO171 is a lean condition. You should get boost anytime you press the throttle whether or not you are in neutral.

carbombss

if u have p0420 more then likely uyour cat is goin bad bc gm cant make converters to save their lives

UtOhCop

You'll never hit 15 psi with the stock pulley. Not even if it was 30 below zero

Darksun

yes you are so right thanks for the input. Now just reach behind your modem over there and pull the power cable please and take your self off the internet.

UtOhCop

I will as soon as my lady friend calls.

Darksun

But yeah on a serious note i guess i can't call it 15 psi exsactly. The right side of the needle touches the left side of the 15 psi line. If its not 15 it is damn sure close to it.

Are you sure i was almost positive in neautral or when not in gear if you hit the throttle the car will not see boost. it was even said in a thread that it is one of the safety features to protect the motor. Can anyone confim this statment?

TANNMANN

My 06 cobalt ss/sc hits 15 psi of boost all the time with a stock pully. It never goes over 15 psi but when im hard in the throttle it will hit 15 psi no prob. What r u all seeing with a stock pully

Drewfu$

Sounds to me like your cat may be clogged. That can cause boost stacking, and you will see more boost than you should.

Been running leaded gas? That'll clog it quick like.

I'd start by fixing that cat problem, then see if that solves your others.

Darksun

I really don't get this freaking car all. All I did was take the bottom off the air box and zip tie the filter into the stock box and the pcm is throwing an f-ing fit.

VaMP

Is he using an aftermarket gauge?

mken

I know I don't trust my tach since I hit the fuel cut-off at 6000 most of the time, and I wouldn't be surprised that the boost gauge was off too.

Darksun

I was going to complain a little bit and be like "than what the hell shoud people trust." I've heard all types of things on the net like you can't trust this and you can't go by that." But When i fall back for a sec and think a little bit the boost guage shows whatever my pcm is seeing and my pcm is throwing 4 codes at the moment so who knows maybe the guage isn't reading right since im throwing 4 codes. One being a Maf code. Can't rule out anything at this point.

VaMP

Yeah the OEM gauge can't boost past 12.5PSI - this has been proven.

silverSS

^^^Ive seen 15psi on the stock gauge

VaMP

next time take a picture..... and don't photoshop it!

Darksun

I was going to actuall make a vid of it but my car may be gone for a while im limping it to the dealer tomm they'll probably give my baby a lobotomy or something while in there custody. I don't like dealers too much.