I have a 94 twin turbo rx7 that has up until recently come up with a boost problem. A quick note first i have rebuilt turbos that only have 5k on them. Ok here it goes, well you see when i am in first gear and i accelerate i dont get 10 pounds of boost, in second i notice that my boost on the primary sometimes comes on below 4000 and sometimes struggles to come up from vac to any boost. Now when i hit 4000 rpm what ever boost i have falls right back to zero when i accelerate, i dont get 10 pounds when i hit 4000 and up, now in order to get it i have to really mash the pedal and then i will get the 10 pounds to redline. One other point i would like to say is that this boost problem i experience seems like an on off switch, sometimes i get 10 in second or third but only if i wait a bit then go into the gas, first gear i never get 10 pounds. So what could be the problem i need to know where to exactly look and what hoses or solenoids to attack.

 

bump

 

sounds like you may have a leaky check valve between the vacuum chamber and the rat's nest.

check here for full details and bookmark that site:

http://home.istar.ca/~dvandit/TurboT...shooting.shtml

 

bump

 

damn, your bumping this without even trying out all the troubleshooting techniques listed on that webpage? That check valve after the vacuum chamber is a good place to start.

 

Go to this thread https://www.rx7club.com/forum/showth...threadid=98645
And this site http://home.istar.ca/~dvandit/rx7stuff.shtml
If you're not willing to research and troubleshoot your problems, then don't ask questions. No one can fix your problem for you over the internet. Your problem may not be hard to fix, but you will have to systematically eliminate the different factors that it could be.
Your best shot is to first do the "hose job," or have someone do it for you. If that doesn't fix your problems, you will already have eliminated a lot of possibilities, and your problem will be more easily found.

 

Thanks guys for your help this bit of information i think will help me troubleshoot my problems, good their is pictures so i know where to look!!!! again thanks guys

 

I have diagnosed the problem now my question is once i take out the check valve is there anything that can tell me visually that yes indeed the check valve is leaking?

 

yes, blow into both ends, air should only flow in the direction of the arrow. It it flows both ways or doesn't flow at all, replace it.

 

THANKS BRO!!!!!!

 

sorry one more thing here which check valve should i be looking at? which one is it in this picture? i know its the one thats between the rats nest of tubes and the vacuum chamber but here in the pic i see two, which one is it?[IMG]C:\My Documents\Rat_sNest2.jpg[/IMG]

 

There should only be one line going to the pressure chamber with a valve on it, the line closest to the front of the car.

Matt

 

I put my Mity-Vac on it, pump it up to either +-10psi, and leave it for 10 minutes. This helps me find the slow leaks too.