Help ! 03 Cobra Losing Boost !

[hsssss03]

I was out crusing around tonight, and i was just have a little fun 2nd to 3rd gear punches, when my g/f noticed that the higher that i got into the rpm's the lower my boost gauge went down, now it has never done anything like that before but i really have never paid that much attention to it. (I mean usually when your in boost you are going kinda fast and paying attention to the road... ) so what is going on?? i checked all the vacuum lines running to the blower (half ass didn't have alot of time) and nothing, why would my boost gauge go from almost 9 psi then slowly go down to 6psi ? i have never heard of this on the cobras, could it possibly belt slippage or boost bypass is screwed up? i have no after market pulley installed, and the only mods are exhaust... also the car seems to be running just fine other than my check engine light is on due to a off road x pipe..
someone please help me out ...

 

[SVTkel]

How high RPM's do you hit when it drops to 6 psi? How hot is it there? The boost falls off at high RPM's witht he Eaton but that is excessive.

 

[KingCobra03SVT]

Well you are basically completely stock so I couldnt imagine it being belt slip since all of your pulleys are stock. Maybe it is the boost bypass that isnt working right.

Maybe take it to a local dyno and have them check it out. Im sure they could diagnose the problem and see whats going on.

 

[hsssss03]

yeah i really don't want to take it there, might have to how do i check my boost byass or just bypass the whole thing if that is the case?

 

[KingCobra03SVT]

I did the "boost bypass mod" heres the link on how to.

http://rpmoutlet.com/boost bypassc.htm

This is a how to and shows you where its at and everything. If you are still having problems and cant figure it out then I would take it in somewhere to have it checked out (dyno) as a last resort. Its good that you dont have like a whole lot of mods so it should be easier to find the problem.

 

[hsssss03]

i have the boost bypass mod done.. the right way i have had it done since i bought the car. so i just zip tied my boost bypass closed and it mad no boost at all what the hell is going on here checked all of the vacuum lines and everything..

 

[hsssss03]

goes to 6psi use to be 8.5

How high RPM's do you hit when it drops to 6 psi? How hot is it there? The boost falls off at high RPM's witht he Eaton but that is excessive.

when i smash the gas to the floor the boost gauge just goes to 6 now not 8.5 any more it was just falling off at about 5200rpm, but now it just stays at 6 sometimes and goes down sometimes i don't know whats going on will data logging help me out alot?

 

[hsssss03]

ok i checked the belt and it is about an inch loose how can i tighten it up some?

 

[ViciousJay]

install a smaller belt

 

[hsssss03]

there is no way to tighten up the belt

 

[bigdog93lx]

I would just get a new Belt. They are easy to install and cheap. The tensioner should have all the slack pulled out of the belt unless its completely unloaded, but I think the belt would break before it stretches that far. You might want to check you Check Engine light codes. They might be throwing off more than just the 02 sensor codes.

 

[Rustan]

Just put a smaller pulley on.

 

[hsssss03]

i have it setting in the garage next to the ngk's i am just waiting on the tune from lund i have to order it, do you like your tune from him?

 

[Rustan]

Yes I like it alot, the #'s in my sig are from the 2nd pull on the 93 street tune he sent me unadjusted except for a 2% increase in fuel at WOT. It was pretty spot on. I haven't ever loaded his more agressive "race" tune either, which is probably good for a few ponies.

 

[CobraBob]

You can't "tighten" up a belt. You have to use the correct size that matches your configuration. The tensioner will compensate for size differences, but it can only do so much. Here's a link to my Belt Selection Guide. Find your configuration and hopefully you'll solve your problem. http://stangshiftergaskets.com/BeltSelectionGuide.htm