Help me diagnose my boost problem...
 

About two years ago I noticed an issue with my car... it's a '93, mostly stock... I have a G-Force ECU (running 1 bar), stock twins, dp, mp and racing beat exhaust. Here's the problem:

When I accelerate at full throttle or close to full throttle, the primary turbo spools up fine according to my boost gauge and I get 1 bar of boost (14.7 psi). At 4.5k rpm, when the car transitions from the primary to the secondary turbo, the boost drops to .5 bars (as I believe it should), but the problem arises when the secondary turbo kicks in. At this point, the car should boost back to full boost, which is 1 bar, but it doesn't. Instead, it gets up to somewhere between .5 and 1 bar of boost, and then the needle just sort of bounces between .6 and .8 and I cannot get up to a full 1 bar.

Also, around the time this started happening, I noticed a strange sound when at idle speed when the throttle is increased slightly... the sound is kind of like an intermittent rattle and it seems to be coming from somewhere near the front underside of the car. Sorry, I don't have more specific information about this problem. I tried to get a recording but it didn't come through very clear.

Here's a video of me boosting...

http://www.youtube.com/watch?v=DWzL8Gv0_dg

I boosted twice during this video. The first time begins at the beginning of the video and you can see (briefly) the boost issue at about 0:04. The second time the acceleration begins at about 0:24 and you can see the boost problem at about 0:28.

Let me know what you guys think... I realize I'm not going to get a definitive diagnosis with this but I'm just looking for some suggestions on where to start.

Kevin

The boost first shouldn't be dropping to .5 bar on the transition. That's a 7psi drop, it should only be dropping about 2psi. That would lead me to believe there's a malfunction with your turbo pre-control which is not letting the 2nd turbo spool as it should.

As for the second turbo not boosting up to 1 bar, the first and easiest thing to check is that your CRV is not leaking.

Here's a guide for mostly everything you need to troubleshoot it: http://www.autosportracetech.com/RX-...leshooting.htm

Sorry for ressurecting an old thread but the problem still persists and I'm trying to finally solve the issue. Is the above statement correct even with an upgraded ECU? I have a G-Force ECU and as best I can remember, it always went from .5 to 1, and then at 4,500 rpms, briefly back to down to .5 before going back up to 1.

Thanks,

Kevin

Check your boost solenoids and the vacuum box above the solenoids. When I was installing my boost controllers, I accidently disconnected a hose from that box. The hoses aren't tight, so I wouldn't be surprised if they loosened themselves. The car would boost fine until the 2nd turbo came on. Then the boost would just bounce between 3 and 5psi, and the car would misfire. Kind of sounds like your boost problem.