I have a sequential problem.. "Go figure", right? LOL!!!

OK here is is..

car is at operating temperature.
Drives fine on primary turbo...
go above 4500 secondary comes on strong... !) PSI perfectly....

Back off the throttle below 4500 RPM or even further.. and you can hear the change in the exhaust note like the turbo control actuator is still open (below 3000-4500RPM) then give it gas again.... no or very low primary and secondary boost (once it goes above 4500 RPM)

Take it out of gear for a second then put it back in gear and the system works great.....

I have replaced the vacuum solonoid for the turbo control actuator, the solonoid for the charge control solonoid, and all the check valves. I have tested all the other solonoids andhose routing.


Should the turbo control actuator still be open to the secondary turbo at such a low rpm? when does it shut?

 

so you are saying that if you boost, then let off boost briefly, then try to boost again, you get ~10 PSI, then vacuum, then only 1-2 psi, right? Just want to be clear...

Are you sure the vacuum chamber is holding vacuum?

 

I get normal boost. Let off the throttle.. try to get boost again and it gives 1-3 PSI that builds very slowly and the exhaust note sounds different (like the turbo control actuator is still open below 4000 RPM)

I am going to put a "T" in the vac line from the vacuum tank to a long hose with a guage in the car today. Any other ideas?

 

Have you checked the black plastic tanks for leaks??

Read somewhere that if they are leaking, the solenoids that rely on the pressure/vacuum from the tanks don't work properly when you let go of the throttle and go WOT again right away...

Hope that helps.

 

I am beginning to have more confidence in the fact it may be the Turbo's themselves or a cracked turbo casting. I just got back from a ride and before I left I put "t" in the vacuum line to the vacuum tank. I put a vacuum gauge inside the car and watched the gauge while things were changing over while driving and the vacuum tank is holding vacuum like it is supposed too. I could see the needle on the gauge move every time the turbo control actuator moved. 4500 RPM and 3000 on deceleration. I am going to do the same thing now with the pressure side.

 

I just put a "t" in the pressure tenk hose and while driving and accelerating everything is normal as well. I have another idea...

 

keep us informed. inquiring minds wanna know

 

My Question:

At what point during deceleration from turbo transition (>4500 RPM) do the Turbo Control and Charge Control actuators close?

Mine will stay open all the way down to 3000 RPM. Unless I put the car in neutral (neutral switch). I verified this with the Power FC sensor monitor function and also with a "T" connector hooked to a hose in each associated vacuum / pressure hose. I can also hear the turbo control valve close at 3K in the exhaust note. I am starting to be convinced that the secondary turbo is really bad.

I also replaced the catalytic converter today and the one I removed was apart and clogged. Both Turbo's spool tons better with the new(er) stock ( 40k mile) Cat. converter but I still have the deceleration recovery problem.

It is either a lazy secondary turbo or those actuators should be closing before 3K RPM.

 

Um...the "problem" you are experiencing is not a malfunction, but how the PFC (and the stock ecu) works.

Once you've boosted over 8 psi above 4500 rpm and get both turbos working, the system will not drop back to primary turbo operation until the rpms drop back below 3k rpm. Until then, you are essentially running non-sequential (sucks, doesn't it?). This configuration is ideal for the track but can be annoying in some street situations.

Some have had luck playing with both the crossover point and the transition, using the datalogit. You cannot adjust those points with just the Commander.

 

That being true.. my boost response at 3500 or even 4000 rpm on the re-acceleration.. is very slow. is that normal for everyone?

 

Here's the latest/:

I need some comparative help from you guys in the list with PFC's:

Sit in the car and (running) with the PFC sensor moniter function on the Commander... Shift through the gears quickly and see if the neutral indicator comes on... Mines does not 100% of the time.. Especially from 1-2.. I think my 130,000 mile switch is causing my issues.. If (while driving) I shift slowly I never have my the issue with the turbo's remaining past transition on a shift. (normal driving)