Help! Primary is building to 10 lbs. Secondary is only building to 6. TCA is fine, new Pre-control Actuator, new lower intake gasket, new primary injectors, good vacuum lines. Fuel computer is NOT connected. Stock settings. Just had turbos off and looked decent, but do have 112k miles on originals (59k on engine). Please help, this is killing me!

 

Have you checked the turbos for cracks?
My twins with 90k had huge cracks and I couldn't get proper boost until I replaced them.

 

Well, the turbo's were off to install the LIM gasket (1/03) and my mechanic said they looked good, but maybe they were the next weakest link to go. My mech. had the car for over a month, but couldn't spend much time on it. Don't wanna rebuild if it's not necessary, but I will if I know thats the problem. BTW, my mech has a FD w/380rwhp, so although he's not a specialty tuner, he is much better than any dealer around here.

 

Sounds like the 2 harness connected to the wastegate/precontrol solenoid that is attached to the Upper intake manifold is switched around. One of the connector should have a whitish dot on it and so does the solenoid.

 

Check anything to do with the wastegate: actuator, solenoid, hoses. That'd be my first guess. T into the wastegate actuator and see what pressure you get there after transition, then test the actuator while the car is sitting and see if the pressure required to move it is close to what you're seeing with the T-test.

 

Check the wastegate first as LAracer says, but I had a similar problem recently with my secondary only that turned out to be a clogged main cat:

My main cat died a few weeks ago. The only symptom I had was that all of a sudden I went from 11-9-11 to 9-5-7; no matter what I couldn't get more than 7psi on the secondary. I was on the track at the time and in a span of about 10 minutes the boost kept falling until it stayed at 7psi max.

I pulled the cat and dumped handfulls of brick and wire mesh out of it. Installed another stock cat and the car was perfect again.

No smoke, coughing, sputtering or anything, just less boost.

Imagine a clogged cat like a clog in a drain. As long as there is not too much water coming through there are no problems, but once more tries to pass than the clog can let by, things back up. Since there is less exhaust volume in the primary turbo (less engine rpm) its boost is not affected as much as the secondary turbo (high engine rpm). My results support this as my primary was only 2 psi low with a clogged cat but my secondary was 4 psi low.

 

Thakns for all the help guys. Wires leading to the wastegate/precontrol seemes right. No white dot at all (too many miles), but seemed worn into position. Anywho... checked CCV (Charge control valve) and page F88 of '93 shop manual says apply 7.89 in Hg Vacuum to port "A" and verify air flows from "B" to "C", well valve opened up at 4.5-5 in Hg. Seems to me that excess boost is venting off... opinions???? Please tell me I solved it!

 

You can T into the hose on the CCV and see what pressures it's seeing before and after transition. I did this and saw 10"Hg vacuum before transition and 7.5psi pressure after. In this case, whether the CCV opened at 7.9 or 4.5"Hg is irrelevent. Unfortunately, I did not write down the pressure it took to open the CCV with the vacuum pump.

For more information about vacuum/pressure tests I did on my car, go here

 

Not trying to sound like an idiot, but here goes... you "t" into it and run a line into the car connected to an additional vacuum guage right?? Or I could just hook it into my existing one correct? BTW, DamonB I now am running a straight exhaust. Thanks again fellas.

 

Yeah, sorry, I should have explained better. I went to autozone and bought a bunch of T connections that fit the vacuum hoses. I usually T into the hose of interest and connect my boost gauge to the T. Then do a 3rd gear run and see what pressure you get at what rpm. Compare that pressure to the pressure it takes to open or close a particular valve with the vacuum pump. Be careful though because the turbo control actuator has two hoses, so it's more difficult to diagnose.

 

Ok, installed a new wastegate and no difference. $100 down the drain. Anyone need a slightly used CRV? Guess I'll try the "t" test today. Any other ideas?

 

FWIW, my problem was a vacuum chamber completely filled with OIL! Replaced the chambers (both pressure and vacuum) with a new chambers, and the second turbo comes online properly now.

I also replaced the PCV valve with a new one to prevent the vacuum chamber from filling up again. A bad PCV will pressurize the oil pan (when under boost pressure), causing an oil mess @ the filler neck, and forcing more oil through the primary turbo, thus oiling the entire intake tract. With a bad PCV valve, the oil will work its way through the vacuum lines, and will ultimately fill up the new vacuum chamber again.

Here's the site I used to help me figure what was going on with my secondary turbo problem...

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

Good luck!

 

WHEW! Problem fixed. While trying to fix the 0lbs. boost problem and replacing the Turbo Precontrol unit my mechanic fried a wire near the ABS unit near the passenger side firewall. Never said what wire and I can't tell. I have a feeling that doing this caused a short in my ECU somewhere. I changed out my ECU and re-installed my PFS pmc and BOOM....10+ lbs. boost! Now I think it was either a short or the extra fuel and boost "unstuck" whatever was stuck. My next guess would have beenthe Turbo Conrtol Unit, but again that would have been only a guess. Either way it's fixed and thanks again to all for their advice. Bonus.... so far no 3k hesitation.