03 cobra boost loss issue

[03KB]

I just purchased a sonic blue 03 cobra last week, it seems to have an issue of not making the boost it is pullied for... It has a 3.5in upper and a 8.5 crank pulley "4lb lower"? on a 2.4 kenne bell. I am hard pressed to see more then 12lbs of boost wot in fourth or third gear. The car does not stumble or miss and shows about 15lbs of vacuum cruising at 55 with the mechanical gauge I am using. It has 60lb injectors, cpr fuel rails, and a bap...Any help would be appreciated.
thanks
alex

 

[Avispa]

Is your boost dump system disconnected or bypassed? If the stock boost dump is still working, that would account for some of the boost loss at WOT.

 

[Anabolic]

also, how do you know you're not getting belt slip? I would suggest getting a new 8 ribbed belt.
here's an awesome size guide
Belt Guide


edit: also what does the gauge read while at idle with no gas being given? are you sure the fittings arn't leaking? i (wouldnt you know) gained 4psi by tightening a fitting & using some shrink wrap on another fitting (it's almost the same feeling as putting the 2$ 50hp sticker on your car off ebay that promises 50hp)

 

[03KB]

Well I spent some time on the car today, I was fairly certain I didn't have belt slip to begin with, but I went ahead and installed a new stock tensioner and new 8 rib belt. Took the car for a hard 3rd gear pull and still not seeing over 12 on the gauge. I looked at all the vacuum lines I could get to and nothing was damaged or loose. The issue I have is one not knowing exactly what I'm looking at. The car is new to me and it has some egr stuff deleted and some vacuum lines capped off. It seems the only way to thoroughly check over everything back there would be to pull the kenne bell off and go from there...my next step will be to trace the vacuum line to the boost gauge and make sure everything is good to go there and hopefully get an extra set of eyes on it before I pull it apart. Side note, had the car to the track last sat with the current boost situation and went 12.2x 4 times with 118-120mph which seemed like low mph... Any other direction would be appreciated. Thanks

 

[03KB]

I will check vacuum at idle tomorrow and get back to you, and I'm having a hard time distinguishing the current boost dump system, it doesn't look like any of the diagrams I have seen so for on my research, I will try and get some good pictures going and see if you guys can point me in the right direction. Thanks again

 

[03KB]

Just checking back in, I just had Jason Roth at competition sound and speed verify the correct routing of my vacuum lines... He suggested I zip tie all the connections to the different vacuum lines which I just finished up and still have the same issue, there is one line to the boost bypass valve the is nearly kinked or at least a restriction that he pointed out. Going to try and re route it to eliminate that... Still scratching my head on this thing.

 

[Dead Mach 1]

also, how do you know you're not getting belt slip? I would suggest getting a new 8 ribbed belt.
here's an awesome size guide
Belt Guide


edit: also what does the gauge read while at idle with no gas being given? are you sure the fittings arn't leaking? i (wouldnt you know) gained 4psi by tightening a fitting & using some shrink wrap on another fitting (it's almost the same feeling as putting the 2$ 50hp sticker on your car off ebay that promises 50hp)

Thanks for posting up the belt guide was looking all over for that :beer:

 

[03KB]

All of my reading and process of elimination has led me to believe that the boost bypass valve is to blame, does anyone have any insight on a test to perform/adjustments to be made? Also if it can be replaced with the supercharger still intact? Any help would be greatly appreciated.

 

[dereknel015]

figure out the problem?