Boost issues! -_-
 

I don't know if I'm searching in the wrong places or what but I can't seem to find anything like the problem I am having. :MissileSm I'm hoping so many Rx-7 owners out there that there will be at least one person who knows what my problem is.
Here's the thing. I recently installed a new 3" down-pipe and mid-pipe from Top Speed. The car was running great for a couple days. I have the Apexi-PFC and have been safely running it on 15psi. But just last week when trying to boost it the boost will go to max but (in the higher RPM especially) then bleed to 2 psi. I thought there was a boost leak but tested all fittings and the intercooler using soapy water and only found a small leak which I fixed. But it still acts the same way. The car besides that seems to be running fine as long as I don't try to gun it in the upper RPM range. Wierd thing also is that I can shift or take it out of gear to let it draw a vaccum and then press the gas again and the boost will have return to normal(Unless I gun it again.) I keep looking for something out of the ordinary. Only thing like that is the air pump seems too be making more noise than usual(No cat anymore) and the knock seems to be getting very high(113 max)
I think now that I have written a small novel that someone will be able to help me. Thnx

Check your rat nest and all vacum pipes. I had a similar issue 3 weeks ago, and had most of my vacum pipes replaced problem solved. However you don't mention how is your boost controller is setup? Are you still using ECU pre-spool and control or you kept the ECU out of it?

I run off the PFC alone. I use it to control boost also.

Is it possible you are collapsing a turbo inlet tube and choking off the inlet? What kind of intake setup do you have?

Dave

You're lucky you're not boosting high, 15 psi on an untuned PFC with the stock fuel system is engine suicide.... your other symptom is a leak associated with the vacuum chamber subsystem.

If you're losing pressure when you hit 4500 rpm and you're running sequential, I know you're problem.

You blew a pressure hose in the rat's nest. It happened to me 5 times on the dyno last weekend. It gives me full boost on the primary but when the secondary comes on, all my boost vents out the charge relief valve ( I think that's the right one, the one that vents the secondary boost during pre-spool) and you barely get any boost. If that sounds like your problem, check your hoses.

Check all your hoses and zip-tie all of your hoses (period!!) . If it hasn't blown off yet, it will if it's not zip-tied. Even if it is zip-tied, if it's not really tight, it'll blow off once it heats up and cools a couple of times.

I am using the aluminum intake box from SR-Motorports. SR- MotorSports
Also could you elaborate on "a leak associated with the vacuum chamber subsystem." please.
Also for everyone. Pics would be awesome.

It seemed that a check valve had gone bad. I replaced it and I still have problems. I can now get full boost. (I reset the boost back to stock.) I thought the problem was fixed until I try to shift. After shifting I get the same problem. The boost only goes up to 2psi. If I let it out of gear, put it back into gear and try again its fine <Full Boost> then if I shift again, ptptpt no boost. Any ideas?

Your turbo control actuator is probably not closing. The solenoids stick sometimes.

I would just replace both of the turbo control solenoids with new ones.

Dave

off topic but what mods do you have and what fuel system setup are you running

quick question.....wen i gun it in any gear my boost gauge only reads 1 psi max...motor is stock.....??

http://i151.photobucket.com/albums/s...7/SSPX0166.jpg
http://i151.photobucket.com/albums/s...ture024fh4.jpg
Mods on car.
Greddy-intake elbow,strut tower bar, turbo piping &, SMIC intercooler.
SR MotorSports Cold intake box
aluminum efini Y-pipe
HKS SSQ BOV
Apexi PFC + FC commander
Blitz Nuir Spec Exhaust
Top Speed 3" stainless Down Pipe + Mid Pipe (No cats)
Stage 3 clutch from COMPETITION CLUTCH
Lightweight flywheel from zoom.
Fuel is stock for the most part.

Oh also when I let off the gas after it won't boost (i.e after I shift form boosting it) I hear a funny sound from under the hood. It sounds like when someone lets air escape from a filled ballon sound but a little higher pitch. like ptheeeeeeer! I don't know what that means but I hope it helps.

Yeah you definitely need to keep your boost at 10psi with a near-stock fuel system. Also, I hope your wastegate was ported, because with those mods you can expect to see boost creep.

I think your boost problem is turbo control solenoids. If your boost is anywhere above 10psi this compounds the problem - so reducing the boost may help solve the problem.

The sound is your BOV, lol.

Dave

Still sounds like a leak associated with the vacuum chamber sub-system to me....which is described in the link I gave you.

The sound is not my BOV I'm not that new to the game. I not a retard, the sound is heard after the BOV goes off. Plus its a SSQV so I think that I can tell the difference. Which solenoids though? there are a shit load. Is there a way to test them?

i dont understand how ur engine still works having run 15psi on stock fuel system?

Dumb luck.

Why do we bother to help if you aren't going to try anything we suggest? If you don't want to deal with it, take it to a knowledgable shop.

charge relief...does it sound like a kazoo it might be charge relief or compressor surge

Yeah it does sound like a Kazoo. Lol maybe thats it. Whats wrong with it though? And also I am using your advice. I used the link to back track and check the vaccum sub-system. I found some hoses that blew off and a bad check valve. I fixed those and there is still a problem. THATS why I am still searching and I like to ask others for their advice. I just wish to know what that kazoo sound was because it was not explained in the troubleshooting link. It is a big help though.

I just finished the vacuum line simplification just recently and it worked ok. But I still don't have secondary boost. Any input from anyone would be great. Still keeping an eye on the vacuum sub-system. Things are starting to get easier to do and I feel like I'm soo close which makes it very fustrating. :Kill1:

Oh well Fuck it Im goin Non-sequential