2ndary boost problem (yes have searched)
 

My car is a 92 (same as the US 93) FD. The only mods are a HKS BOV, extra cold air inlets on the stock K&N filter equiped air box, apexi avcr boost controller, and a Blitz cat-back system.

I bought the FD stock apart from the HKS bov. I attached a boost gauge to find it is only running 6.5psi, drops a little 4000rpm, and then back to 6.5psi. Also if I floor the car from cruise at any rpm above ~4000rpm I will only get 1-2psi.

I decided to put on an avcr boost controller to eradicate any possible problems with the factory Wastegate and Turbo Pre-Control Solenoids. At the same time I installed a cat-back system. On 42% duty cycle I will make a best of 8.5psi (sometimes), the boost should be higher from what I have heard from others on this forum running the avcr. The problem with lack of boost when flooring it from 4000rpm still remains. This particular problem points to maybe the pressure of vacuum chambers leaking, however I have checked both of these and they keep there pressures. Maybe the TCA? Any checks i can do for the TCA? I have also checked for any splits in the rubber intake hoses.

As for the low boost problem, maybe exhaust restriction (still have standard DP, precat, and main cat), but i would expect this to only effect the boost in the higher rev range.

Cheers,
B

I also have a JDM 1992 FD. I am running the stock BOV's, Stock downpipe, HKS intakes, 3 inch pipes all the way back, and a chipped ECU. Your boost should be way higher. I usually run between 12-14 psi under boost. Maybe the twins are just bad?

the twins were recently replaced with 98 turbos, the previous turbos apparently acted the same way (though they needed new seals). i agree i should be running more boost then this

Have you replaced the rats nest hoses and/or check valves recently? One my car (just did it), every check valve in the system was leaking. Also check the pressure tank for leaks.

Sonny

i had a look under there last night and it's one hell of a nest... i mean mess... :p:

i disconnected the vacuum hoses from the pre-control and wastegate solenoid and blocked them off. rechecked pressure and vacuum chamber. and checked most of the check valves i could see. i was hoping to pin down a few problem areas before i decided to replace all the vacuum hoses. i wanted to check the turbo control solenoid and vacuum fittings, but could find it. i assume i will need to take the UIM off before hand.

Do you know anybody you can swap good parts with? It sucks trying to trouble shoot because you can't really do it when the car is running. I would try swapping out solenoids and stuff before I replaced everything. See if anything makes a difference. Just an Idea. I think any way you do this it is going to be a huge pain in the ass. RX-7 Vacuum lines are a rat nest.

i may have tracked it down to the turbo control actuator vacuum solenoid (though i'm still convinced this may be one of many probs) i hooked up a boost gauge inline and found it didn't put out any vacuum after 4500rpm. the pressure solenoid seems to work fine

it would be very helpfull if i could swap parts with instead of me replacing suspect items with new

Well...Good luck with it. Shoot me an email if you need any 1992 parts or if you have any other problems. You are the only other person with a 92 FD that I have ever run in to. Maybe we can help each other out.

Hey Ohnigiri, I also have a 92 Japspec RX7. I'm stationed here in England. I hope I can get some helpful info from you.

I have a '93 FD and am experiencing almost the exact same problem. Please let me know if you have any luck.

will do

i increased the duty cycle setting on the avcr to 55% to get 0.7kg/cm^2 (9.9psi). i only reach 10psi by about 5000rpm. some FD owners reach 10psi by 2500rpm. :confused:

i was under the car last night and notice the TCA had exhaust soot around and where the arm come out :confused: :confused: :confused:

i fixed one problem, where the rx wouldn't boost when applying full throttle at anything above 4000rpm. the Air Bypass Valve vacuum fitting was connected directly to the manifold, not its designated solenoid

I was out last night studying for the speed exam and was only boosting a .6 with the pedal to the floor through the top of second gear. I normally hit 1.2 bar right. Thanks to the light of 3 cell phones I was able to find the vacuum line that had popped off somewhere in the nest. Go figure. It was making a really weird "whoo-whoo" noise when I would decelerate. Once I reconnected it the car ran great again. I have since decided to change all of my vacuum lines and zip tie them all. What else are you gonna do on your days off?

ORX,

You should check that you have the restrictor pills present between the compressor nipples and the solenoids. If you do not have these it will be very hard to regulate the boost with just a small solenoid.

If tey are 99RZ (not 98) turbos, then the restrictors are already on the compressor outlet nipples themselves.

ok, i have read elsewhere you need to remove the restrictor pills when you install the AVCR. i have considered putting them back in and seeing what happens.

hey guys, i am having the same issue on my '92 FD. I'm only boosting .14 bar at open throttle until i hit ~4000 rpm; then i get nothing, only a really bad hesitation. i hooked up my avc-r to try to correct the problem, but i still have the same problem. any ideas? also, when you hook up the avc-r, you disconnect both the wastegate and pre-control soleniods, and block them off, right?

i finally fixed my problem. the problem got so bad i had only 2psi. had a DP installed and found the main cat had fallen apart. a big chunk of cat would get stuck in the outlet of the cat and this would explain the hissing noise i would hear. now the rx performs like it should. a DP is must on these cars!

i've been told you should hook the avcr upto only the wastegate actuator, not the pre-control actuator.