i have had prob. with boost above 4500 ever since i purchased my 93. the other day i took off the intake to see if i could find any vaccume lines the were wrong, off, or cracked, ect. i found no prob. the previous owner had the motor rebuilt and had new sil. vaccume lines placed on the car. i could get boost above 4500 every now and again, but it was not reliable. after i putt everything back together( after finding the check valve that goes to the vaccume tank on the top of the motor was backwards) i took the car for a test run. the car ran great. had power through the whole rpm range. then the next day boom, back to her old tricks again. The weird thing is, if the car goes over 4500, and the boost does not come in then when i grab the next gear, even if i am below 4500 it does not build boost. i can here the turbos spulling up, but there is no boost. any sug.??

 

Has to be a boost leak somewhere. Are you sure there are no more hoses on backwards?

 

not sure. will double check this weekend. if problem cannot be addressed then i will prob. go to a single settup. i would like to keep the sequential settup for now though.

 

What you describe with "when i grab the next gear, even if i am below 4500 it does not build boost." sounds like it is the Turbo Control Door being opened & never being shut.

Look at the two hoses that run from the metal tubes on the front of the motor to the Turbo Control Valve. This is the valve that bolts to the ACV manifold & is only visible after you remove the PC & WG solenoid valves (& pull the UIM).

Make sure the two hoses to the TCV are not crossing. If they are crossed then you will get boost the first time you run through both turbos, but then the TC door won't shut...

This seems to be a common mistake people make since crossing the the hoses makes for a larger radius in the hoses & relives the chance of pinching.

Also the CRV hose could be split venting the rear turbos boost.

Good luck.
Eric.

 

eric i thank yoou for your advice. i will check it out this weekend. i was hoping to get this fixed so i could run my stock turbos for a bit longer. i came really close to just putting a single convertion on my car. i was fed up with the unreliability of the sequential system.

 

Make sure the check valve on the pressure tank is installed in the right direction and is working proplerly.

 

when i took off the intake the check valve that leads to the vaccume chamber, on the top of the intake, was the only thing that i did find wrong. if it is not working properly could it have this kind of "overall loss of power" effect from the turbos? another question i have is: What is the blue two prong female conector that sits on top of the motor that is under the vaccume chamber used for? i have searched for a place to connect it. i have found none.

 

I found the problem described below on my car after the dealer worked on it just before I bought it. It ran fine and had good accel but later installing a boost gauge indicated the problem.
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From autosportracetech.com:

Wastegate and Turbo Pre-Control Solenoids: If you are getting a solid 6 psi from 4,500 RPM up, Check the electrical connections to these two solenoids, as they can get mixed up while working on the engine. From the front of the car, the right hand solenoid and the electrical connector of the engine electrical harness have a painted white dot, these two go together. Note that over time these painted white dots tend to dissapear.
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Are you referring to the plastic pressure tank in front of the intake not the vac tank? I broke the check valve going to the pressure tank. While waiting for the new one I temporarily connected the two hoses going to the tank together. Basically all this does is remove the big bulge (pressure tank) in the line. It doesn't seem to run any different this way.

 

Kind of off subject, but if you are looking at going single maybe you should consider looking at BNR upgraded twins first. Just run them non-seq. From what has been reported so far they produce killer power and spool extremely fast as well. The cost is also lower than that of most good sized single setups. Hope that helps. Laterz.

Zach

 

i like the quick responce of the sequential system. that is why i was trying to use it for a while longer. what have you heard about the BNR twins.? The only downfall that i have with getting a singe is i would lose much of my low end power. i drive the car almost everyday(city traffic) and the low end helps out somewhat.

 

I know this doesn't fix you current issue. But if convert to Non-sequential, like I did, you can elimininate ALL of your boost issues!

Check out the How-to here: www.dontbearikki.com
The conversion is easy, about 1-2 hours, and is reversable.

 

i changed the wpc & the turbo precontrol sil. back to the way that they should be. then i took the car out to try the results. see came in strong all the way up. at 4500 she comes in unusually strong, however there is no sign of a spike from my boost gage. i dont know if the problem is fixed however, it worked properly all day. i am going to keep my fingers crossed. i thank everone for their advice. this forum is very usefull.