BoOsTin FD

My Fd was started to give me some slight problems with boost. I think I know what the problem is I just don't know the reason it's doing it and how to fix it.

Basically what happens is it won't go back to sequential system once it goes past 4500rpm. It's becaming ubnoxiously loud just like it's runing non-seq. Then today all of a sudden came back to sequential system and it's not loud anymore.

However, as soon as i redline it, it stays there again. Also, I get no boost till 4500 and only then i get 8-9 psi. That is only if it gets stuck in non-seq mode.

What i want to know is what controlls switching between seq-and non-seq other than TCA.

My mods are full exhaust, intake, PFS PMS, profec b, PFS IC, etc.

Amel

BoOsTin FD

so nobody knows anything about sequential system? I guess all you guys run single turbos

911GT2

The TCA just controls the pre-spool of the secondary turbo. The big thing to look for in your case is the CCV, it's what opens to allow the secondary boost to be added to the primary, and probably your issue if you're seeing no boost pre-4500 rpm.

This little bugger here:


Thats not to say it's the actuator itself thats at fault, something that provides it with vacuum or pressure could be not working correctly, and causing that CCV to not work. Take a look at it and the things that control it.

Check out the rest of the autosportracetech site for diagnosis and repair info.
http://www.autosportracetech.com/RX-...leshooting.htm

BoOsTin FD

problem is that it works sometimes. Then sometimes it just takes forever to get back to sequential. It's like something is keeping it from switching back. I'll have to do some digging.

Thanks for the link.

Amel

DrunkenBowler

If I were you, I would just move the your motor from seq. to non-seq. Get rid of all the vacuum hoses and selonoids. Those things never work anyways.

BoOsTin FD

I need to bump this thread, as I got nowhere. TCA and CCA work both fine.

Every time i redline it, it gets stuck in non-seq. I HATE NON-SEQ. It's loud and it sucks with lag.

I get no boost, not even 1psi till 4200 rpm or something like that. I pressed accel. all the way to the floor and nothing it accelerates slow until it gets to 4200 and then it just kicks in, but i only get 9psi afterwards.

I know I have no leaks as i have check all hoses and couplers and all that crap, and no air hissing is coming from the engine.

Anyone have any other ideas?

Amel

Icemastr

iTrader: (2)

How would non-sequential make the car louder? I remember reading before that once you go past 4500rpms under some circumstances the turbo system says in non sequential until you do something then it goes back to sequential, can't remember the specifics so maybe something is staying stuck. If you have a full exhaust you should be getting 10 psi by around 3700RPM if your valve for the secondary is staying open all the time.

BoOsTin FD

I wish i know why it's louder but I don't. It sucks *** and I hate it. I just know it's getting stuck there for some reason every time it gets to non-seq. It's like it won't go back. Either some kind of acuator or solenoid or some crap is not switching back.

I hate to start diging under that manifold again, only to find out it was something by the turbos or something.

Amel

BoOsTin FD

Bump!

BoOsTin FD

Does anyone know then, Why I can't raise boost at all anymore past 9psi? I got profec B and it no matter if i switch it to hi or low and turn the **** it stays at 9. This is really starting to **** me off.

Amel

rpm_pwr

stuck open CCA isn't going to do a damn thing to your exhaust noise. Whether you like it or not, your problem is your TCA system. Could be the solenoids, could be the gate, could be the actuator. But it HAS to be one of those three.

As for your boost problem - see rule #1 - fix the primary boost first.

austinsFD

Every time i redline it, it gets stuck in non-seq. I HATE NON-SEQ. It's loud and it sucks with lag.
Amel [/B][/QUOTE]

if you launch you won't have much lag

donny

did you ever fix your car because mine is doing the exact same thing. I have checked everything.

BoOsTin FD

No, I didn't. I checked everything that is related to the Seq. system and everything is working fine. It's happening a lot less, but when it does get stuck, it takes a while to get back on.

It's really pissing me off. I also can't wot at all now because it's giving me some kind of either fuel or ignition cut. I'm going to replace the turbos by the end of this month and I hope all these problems go away.

I can see a shitload of oil in the ic piping, and if i put the midpipe it smokes a lot. So we'll see after that.

Amel

FDNewbie

iTrader: (10)

I THINK the way it works is once u go past 4500rpms, the 2nd turbo kicks in, and you're essentially running parallel, and it'll stay running parallel unless the revs drop below 3000rpm i believe. Thus, for example, if you're really tryin to dip, and are sHiFtInG mAdD qUiCk Yo lol, you should stay parallel throughout your run.

It makes sense too because the only time you wanna run sequentially is at lower rpms, to get you up and moving while the 2nd turbo is spooling up. But once you're in motion, you wanna make the most outta both turbos, equally.

jetmech77

Hey I was really consitering going parallel on my turbos..so I wont have to play with the Rats nest... What do you mean by Louder?????

crazyrx7

I think its your precontrol valve that is sticking open. In the sequential mode the primary turbo has to make at least 7 psi in order to start prespoolin the secondary turbo. Once 4500rpm hit the secondary turbo kicks in making the car louder than it would be just running the primary turbo. I know because I have ran my car in both sequential and non-sequential modes and the non-sequential mode is louder. Any way what I think is happening is that your prespool valve is sticking open once it transitions into secondary boost so then when you shift your are in non-sequential mode until it finally slams shut then you're back in sequential mode. The actuator (where the precontrol valve is) is located underneath the wastegate actuator. Make sure that it is on securely and that the C clip is on. Thats my thoughts. Hope that helps you out a bit.

R.K.

DUDE21

Wait, I got a question. It might be a liitle off topic but, If you do a single turbo conversion, does it clean up the engine bay by getting rid of most of the the vacuum hoses, selonoids, and the rest of the stuff associated with the stock twin turbos?

FDNewbie

iTrader: (10)

That's exactly what it does. Going non-sequential cleans it up too...

BoOsTin FD

That seems logical. However, Should I be non-seq at idle and at 2000rpm and up and so on all the time until the damn thing finnally after 5 min decides to go back to sequential?

Amel

FDNewbie

iTrader: (10)

LOL...No. Sorry. Don't feel bad though, my FD's givin me crazy problems right know too. Fix one thing find 2 more problems haha

MichaelFregoe

iTrader: (1)

Any solution on this? I am having identical problems. Throttle position sensor??? LOL I have a PFC. Are you guys running a stock ECU?

BoOsTin FD

No. I have a pfs ecu. It's a piggyback. I didn't have much time to mess with it. Still waiting to replace my turbos and clean out injectors. I don't know what else to do. It's bugging the hell out of me.

Amel

BoOsTin FD

I'm gonna bump my old thread back on as i'm having the same problem. It keeps getting stuck in the non-seq mode every time i redline it.

The thing is i didn't have this problem for a long time now and after i replaced my engine again... It came back. I don't know what i did last time to fix it... but i know i replaced the twins, went simplified seq, replaced engine got power FC, etc.

Other then the TCA what else actually makes it switch back and forth from non-seq to seq?

Cgotto6

iTrader: (8)

Youve done the KOKO test...Right? If so, I would say that your turbo control actuator is bad...

Drive your car till its warmed up...but dont boost on it at all. Pull it back into the garage, turn it off...Do the koko and watch the actuators.

Then go out and do a wot run and hit redline and make your car go into the symptom it does...Park in garage, do KOKO test. I bed you the TCA wont move...