VolkSL

iTrader: (1)

I've searched this quite a bit and I think I'm on the right track but wanted some clarity from you guys who have been through this before. I'm still learning all the painful beauty of the sequential system as I came from about 13 years of building honda's which are much simpler.

Setup:
1994 FD - stock except downpipe, midpipe, and racing beat exhaust. Has boost gage.
Removed 1" hose between ABV and intake for diagnosis reasons
Replaced all vacuum hoses and check valves per Dale Clark's guide

Here's my problem:
Boost spools to solid 10-12psi up to 4500rpm, then does the little dip trying to pre-spool the second turbo, then just drops down to 2-3psi and stays there. On-off'ing the throttle does nothing, still stays at 2-3psi so I know it's not a check valve.

Now, when it's doing this, no air releases from the ABV when I let off the throttle. Also kinda funky, rarely, just rarely, the second turbo spools up and i get 10-12psi above 4500 after it does it's little dip at the transition point.

My next plan is to re-connect the 1" hose between ABV and intake and remove 1" hose from CRV and intake and listen to see what happens. I will update you after.

My question is, since you guys have been through this, is there some common thing that needs to be replaced to fix this? I just don't want to have to spend alot of time/money figuring this out if there is a most certain/common thing that fails that I should just try first.

I sincerely appreciate all your help as I love this car and would love to make her run the way she's supposed to.

Thanks

needspartsnow

iTrader: (10)

Under the car by the right front tire there should be a hole in your plastic belly pan . Look up in there and see if one of the metal rods that comes from the actuators is fully attached to the bottom of the turbos. There's an e clip that holds the rod on to the turbos, sometimes it breaks or falls off.

Mahjik

iTrader: (1)

Check the Secondary Turbocharger section:

Troubleshooting

djseven

iTrader: (56)

Get the primary turbo staying at or below 10psi with a boost controller before fixing the secondary boost. If you are creeping to 12lbs on the primary you are going to spike to 13-15psi when you get the secondary control issue sorted out. Which will very shortly lead you to getting a rebuild. Remove the boost restrictor pills from the two lines going from the primary turbo compressor housing to the wastege control and turbo pre-control actuators. This will limit boost to 8-9psi and keep you from making a $3-5k mistake.

VolkSL

iTrader: (1)

Thanks guys. I'm very familiar with the secondary turbo section of Troubleshooting as I've used it for my initial investigation of the primary turbo. Good info on there and alot of stuff to check.

I was just hoping to narrow it before buying a mityvac and testing everything if there is something more common based on my symptoms (2-3psi over 4500rpm, no whoosh sound from ABV when i let off gas over 4500rpm). I'm gonna do what Needspartsnow says and check the actuator arms and make sure it's still connected. I'll do that and remove the CRV hose and see if it stops dumping air over 4500rpm and update you all. I'm just hoping it's something simple and not the charge relief solenoid as those things are $$$.

And totally feel you about the high boost. I've read some guys boost up to 10-11psi from the factory so didn't think it was a huge deal, however, I am in the market for a PFC and am not pushing the car until I've got it tuned. But for now, I'd like to get the car functioning properly before doing so.

Thanks again guys!

pd_day

iTrader: (6)

I had this problem when I first brought my FD.

Turns out the hose to the boost chamber in front of the alternator is disconnected.

After reconnecting and zip tie, everything is gravy

VolkSL

iTrader: (1)

WOW so I went to remove the 1" hose on the CRV to go test it out but then the pressure chamber was staring at me and I was like...Alright, I'm gonna take this thing off to see what's going on underneath. Believe it or not, I removed the pressure chamber and underneath it, behold a vacuum line that popped off my check valve. Replaced the hose with new silicone hose, zip ties, put back together, and wow...boost is back. You were right on pd_day.

Love this car. Definitely need a PFC or similar as my boost does spike to 13psi before dropping back down. I'll get on it.