My secondary turbo isn't giving me any boost i see the boost gauge just start going down after 4500, also the gauge only reads about 7.5psi, but it also sits at about 2.5 inhg when the car is off so i'm not sure. since i've had the time to work on my i keep finding new things such as this. what could be the cause of this? it was doing fun a few days ago and now i don't even feel it.

 

There is a little clip that holds the pre-control rod on. That little clip might have falled off. Also are you running the factory cat in the midpipe? If so that might be plugged and not allowing you to achieve boost. Also you might want to get a good boost gauge so that you can tell whats really going on. Your primary turbo must make 7psi inorder for the sequential turbos to work.

R.K.

 

where's this clip at? I have a defi d series gauge, which is a fairly good one, just this one seems a bit off. also the problem kind of just snuck up on me. it was fine one day then over two days began to diminish

 

anybody

 

You have to crawl under your car. Its the pre-control rod on the turbos. If your looking at the turbos from the front there are 2 actuators; the top is the wastegate and the bottom is the pre-control. They both have rods that are attached to flapper doors. The top one controls the boost and the second (bottom) pre spools the secondary turbo.

R.K.

 

The more I read your problem the more I think that the main cat is plugged. Is it safe to assume you are still running the factory cat in the mid pipe?

R.K.

 

that would be correct, i would be inclined to agree with that but the fact that it just came within the last two days makes me skeptical. i'm going to try rerouting my boost gauge hose from the map sensor to the UIM see if that may make a differance and i'll check that rod as well. it's kind of near the control arm on the actuator right?

 

just do the "hosejob"... also change the precat... good luck!

 

i'll go check that right now, thanks

 

I'll bet you have a split or loose vacuum hose. Lift the UIM and start inspecting.

Dave

 

i actually found a little s-shaped hose that sits right behind the alt, must've came off when i put the new one in and pulled the vacuum box. it's still raining hard so once it lets up i'll take the car out and we'll see what happens. if it still persists i'll un-T the boost gauge from the map sensor and run it to the UIM nipple, but i doubt that'll do anything since the line should be pressurized regardless. Thanks again

 

The MAP and UIM nipple should provide the same readings, yes.

Dave

 

boost reading was still a bit low, around 8-9, unfortunately my quality defi gauge sits a tad low, but the lower than normal boost can probably be attributed to the cat.

 

If it reads 2.5inHg with the engine off, then I'd say you're about where you should be.

A clogging cat usually has a gradual effect as the RPMs go up.

Dave

 

good, then i won't have to worry about it for a while, thanks dave