Hi, long time no post...and it's a boost question at that. Sorry!

Please help. My 2nd turbo does not like to kick in if you gas it hard over 3500 rpm. If you let the rpm's drop below this and floor it, it comes on strong with no problems whatsoever. What would cause this and how to fix?
I've search the forums but there are soooo many boost threads.
Once again, sorry to add another boost question to the list!

 

Sounds like you popped off a vacuum hose. I've had pretty much the same problem before.

 

Do you remember what hose it was? There's more hoses than there are garden hoses at home depot!

 

You might want to take a look at the check valves near the upper intake manifold. From my experience I have found that some of the check valves only work when you blow through them really hard when they start to go bad. When you check them you should be able to blow through them easily. If you feel like you are trying to blow up one of those really small ballons at a birthday party then chances are the check valve is bad.

Of course I'm just taking a guess that this may be part of your problem, but it is worth a shot.

- Cody

 

You have a vacuum leak. Replace your vacuum chamber check valve. Check your vacuum line hoses leading from the vacuum chamber to the rat's nest. Check the vacuum hose leading from the rat's nest to the vacuum hose leading to the turbo control actuator. Check your charge relief valve and air bypass valve to make sure they are working properly. Check your turbo control solenoid (this also has problems with 2nd turbo coming online). Check to see if your vacuum chamber is holding a vacuum (use a mityvac and see if the chamber holds 20 inches Hg). Check to see if your charge control actuator and turbo control actuator are working properly (key on/key off sequences after the car has idled for awhile should actuate the charge control and turbo control actuators).

For more detailed info read this ENTIRE link:

http://www.autosportracetech.com/RX-7/rx7stuff.htm

 

Wow.. this really helps.. I have this exact same problem.. My secondary turbo comes and goes.. And I think only comes on when Its pushed from start..

thanks guys!

 

If the problem is worse in 1st/2nd gear, and reliable in the rest of the gears, look @ your turbo control solenoid and actuator...

 

Thanks so much for all the advice. It's really appreciated. Now, will someone check the hoses for me? :-) Just kidding!

 

BINGO!

 

It's definitely in all gears. If it's not in the hoses, maybe it's my horn fluid!

 

Right after you check the horn fluid you will want to check out all your check valves....the Green & Black...and the White & Green ones...I had this same porb and it was becasue my check valve was split...check the one right below the Pressure Chamber first. That seems to be a the popular cause. the pressure chamber is the black tank located right infront of your upper intake manifold and and is bolted down on the UIM and also to the bracket which holds the plastic cross-over pipe (aluminum if you have the efini y-pipe) Good luck, I understand how frustrating this one is...

 

The pressure chamber check valve affects primary boost response. The pressure chamber is filled with pressure from the primary turbo.

The secondary boost problem stems from a vacuum leak which is affecting the proper function of the charge control and turbo control actuators. These actuators allow the secondary turbo's boost pressure to be added to the primary turbo's boost.

If the all the gears are affected (secondary boost problem in all gears), then you might be able to cross off the turbo control solenoid as being a problem (which is good, it's $70)...

 

i think im having the same problem... but my second turbo is kinda going in and out when it should be spooling... it kinda hick-ups... not sure if this is the same or not...
-Keith