violentsnail

I'm running into a really strange problem with turbo spooling on BNR stage 3 seq. twins. Everything is stock (airbox, intercooler, downpipe, ect.) I have both the stock ecu, and a Power FC.

Heres what the boost pattern looks like with the stock ECU:
12-5-7

The car boosts hard to 12lbs @3400 RPM and stays solid until 4500. It switches into the secondary and the boost only runs about 7psi and feels flat accelerating. Sometimes the boost runs @ 0lbs running from 1st to 2nd.

Now for the real oddity, with the Power FC in:
0-5-7

The car is pulling flat boost readings until the crossover to the secondary, and then spools hard to 7lbs. The car will continue to spool fine until RPM drops below 3k. After the car reaches temperature or KOKO, the boost pattern is totally flat, 0-0-0.

With the FC commander, I can tell that the car is reading the boost correctly, but when I try to adjust any of the boost settings, I get nothing. None of the controls in the PFC boost section work at all.

Any suggestions? I'm completly out of ideas.

twistedriver

Do you always get primary boost with your stock pcm? Even at operating temp? If you are not getting any primary boost i would start by looking for a boost leak and make sure the primary is boosting at all.

TK7

iTrader: (6)

ive been fighting the same pattern u are, for the past 6 months!

10-5-7ish

id give anything to fix it. i really dont know what else to do.


i will be watching this thread tentatively

violentsnail

The stock ECU always boosts 11-12 lbs when in the primary, but its a dice roll in the secondary.

I'll probably take some time this week and do a check on all the vacuum lines and see if there are any leaks.

Flybye

Yeah it could be a number of things. The Turbo control actuator, the charge control valve, the charge relief, etc.

A good place to start would be the lines attached to the vacuum and pressure chambers, and the one way valves. They are made of plastic and the nipples could easily break on them. A lot of people forget about the vacuum chamber next to the PS pump. After you do pressure/vacuum tests, the next thing to do would be to install a t-line in various locations to see if that area is seeing pressure/vacuum as it should or pressure/vacuum check the actuators directly.

And never do blow tests on anything. Always use a good quality vacuum/pressure device with a gauge.

TK7

iTrader: (6)

^ ive replaced all of those, including the turbo control actuator, all check valves, with vyton valves, and all turbo related solenoids.

so i guess the only thing left is the charge control valve?

twistedriver

Before you change that valve you can test the operation of the charge control valve by applying vacuum to it. If it holds vacuum and are sure that everything is working right. Take the cross pipe off and make sure the charge control valve door is closing all the way.

jmadams74

It doesn't make sense to me that you get good primary with the stock ecu and 0 primary with the PFC? Also, I don't think the secondary can even kick in until you make at least 7 or 8 psi on the primary (did you buy the pfc new? has it ever been tuned to your car?). Vacuum lines, check valves etc. are either working or not, not dependent on ecu. Disconnect the electrical plugs to the wg and ps solenoids (the ones easy to get to right on front passenger side of UIM. You should get 7psi in this configuration no matter which ECU you are using. If you are getting zero with the pfc, it is sending some inappropriate command or something just isn't set correctly. Do you have a datalogit to check transition, etc. Follow the instructions in the FAQ's. First get the primary working properly, then work on the secondary. Good luck!

Flybye

Alright, here is my full documentary:

The prespool flap acts as a mini-wastegate to the 1st turbo. If I remember right (and someone do step in to correct me if needed as it has been a while) the main wastegate does almost nothing before 4500rpm. The prespooler is one of the ways for making adjustments to prevent boost spikes at 4500rpm. The Turbo Control actuator is the main unit which allows exhaust to get to the 2nd turbo. The main problem with this actuator is that it is both vacuum AND pressure controlled. If one of those elements is missing, an insufficient amount of exhaust will reach the 2nd turbo. Turbo control not opening and with the waste gate open, you get a **** load of exhaust going no where.

BUT....

We also have the Charge Control Valve and the Charge Relief Valve.

Charge Control Valve: Allows all boost from 2nd to mix in with 1st. It is the big "Ok, you guys can now join forces" valve. What happens if this thing stays shut? Air from the the 2nd turbo would never mix in with the 1st turbo. This valve should be fully open once 4500rpms is reached.

Charge Relief Valve: Is the valve which vents pressure from the 2nd turbo to atmosphere while it is PRESPOOLING. This valve should be fully closed once 4500rpms is reached. You can imagine that if this valve stays open , a lot of pressure will be lost.

And there you have it. The system becomes intensely more complicated as it reaches 4500rpm with the most activity taking place at 4500rpm.

So what is the worst case scenario? Turbo Control is not letting a sufficient amount of exhaust reach the 2nd turbo, the Charge Control Valve is completely closed preventing the little bit of pressure the 2nd turbo is generating from mixing with the 1st turbo, and the Charge Relief is stuck open venting all the pressure the 2nd turbo is creating. And the ECU thinks everything is working fine with the 2nd turbo control system and it opens up the wastegate thinking it is venting exhaust for 2 turbos when it is only venting exhaust for 1 turbo. There goes the rest of the exhaust going to the 1st turbo.

Now remember that the Power FC controls the wastegate differently than the stock ECU, but it STILL needs to control the rest of the sequential system. Oh so what if the Power FC is doing this funkiness. It is a clear indication there is a problem with the sequential system.

The first production sequential system was on the Porsche 959. The 2nd was on the FD. Ya gotta give Mazda a little bit of credit for creating this mess at the end of the 80s when noone had twin turbo sequential setups.

TK7

iTrader: (6)

let me verufy something. during the KOKO test, the trubo control actuator should move completly in and hold, correct? if not, could someone describe in detail what it should do.


mine does move, but very slightly. the rod basically just jerks in a short distance and then immediatly releases.

gracer7-rx7

iTrader: (16)

stock ecu shouldn't be seeing 12 PSI of boost.

have you checked your cat? it could be clogged. that often shows up as the secondary turbo not being able to hit normal boost levels.

dgeesaman

iTrader: (7)

That is correct.
That suggests that you're having turbo control solenoid troubles or pressure tank troubles.

Start with checking that the pressure tank is holding pressure consistently before moving onto solenoid issues.

Dave

Flybye

Check the pressure AND vacuum tanks.


Violentsnail, have you looked up the vacuum diagrams and the turbo control diagrams?

violentsnail

Yeah, I've got a copy of the turbo flow diagram and the vacuum line diagram.

So if I get this straight, when I disconnect the UTB electrical connetors that control the PreSpool and Wastegate solenoids, I should see 7psi across the board? And I should see 7psi if all of the vacuum line/chambers are working within spec?

Just trying to gauge if unplugging the UTB electical connectors will eliminate them as a potential problem, or if it will tell me if I have a vacuum leak.

jmadams74

Even if you get 7psi, it doesn't necessarily mean everything else is working properly. I still haven't seen anything that would explain primary turbo 12 psi with stock ecu and 0 psi with PFC? If you get 0 psi with wg and ps solenoids plugged in and 7 with them unplugged, you will know the pfc is doing something to your wg or ps that it shouldn't. . .but I've never heard of this problem. are you sure the ONLY think you are changing is the ecu when you go from good primary boost to 0 primary boost? Since you get good boost with stock ecu, you know the car is capable of making boost (doesn't mean there are no problems elsewhere). But to get no boost, either you CCV is open during primary and you're bleeding pressure through CRV, your blowoff valve is open, or your wastegate or prespool valves are not functioning properly (but if they weren't functioning at all you would still get 7 psi). Something is missing to this puzzle. Also, you didn't answer where you got the PFC and if it has ever been tuned on your car?

zack4173

iTrader: (3)

Have you checked to see if your Pills are still in place for your wastegate control acuator and your turbo precontrol actuator. because if those arent in the turbo will run 7 psi. I think one of the pills may have gotten twisted in the hose.Thats why I was running 7 PSI at least and its a quick thing to check.

violentsnail

The only thing i change is the ECU and the boost pattern is drastically different. The PFC has not been tuned, its straight out of the box with the Commander.

Yeah, I'll check the pills to see that they are still present. If there is one missing, would it be more prudent to try to replace it? Or would it be a better idea to get a boost controller at that point.

violentsnail

Looks like the downpipe I installed solved the 7lb problem I was getting with the secondary turbo. Backup from the precat must have been limiting exhaust flow. It also solved a problem I was having with engine temps hanging out a few degrees C hotter than it should be.

I also had the opprotunity to go over the majority of vacuum lines while I had the intake piping off, replaced a few of the lines. I also verified that the pills were in the correct lines. I'm still not getting any boost in the primary. I can hear it spool up fine, but it seems like the pressure is getting vented. Could this be a symptom of a bad Charge Relief Valve?

Mahjik

iTrader: (1)

Most likely the Charge Control solenoid (or vacuum routing):
http://www.autosportracetech.com/RX-...erOverview.htm

You could try switching solenoids and see if it fixes is (i.e. switch the Charge Control with one of the emissions related solenoids for a test).

violentsnail

I tried switching the 2 valves, the Charge Relief Valve and the Air Bypass Valve, and got no difference between the 2. I did notice something odd, when I pulled the vacuum line of the CRV, it vented boost/vacuum. Is the valve in place of the CRV supposed to hold vacuum/boost after the engine is off?

Mahjik

iTrader: (1)

If the solenoid is bad, switching the valves won't show that. This is why I suggested switching the solenoid as those valves rarely fail. However, you need to look at the Charge Control solenoid as I mentioned before. If you have boost after 4500 rpms, then your Charge Relief system is working fine.

violentsnail

Yep I think you're right about the solenoid. I dug under the rats nest and i couldn't remove any of the vacuum lines without breaking stuff off the solenoids themselves. they were completely baked brittle. Looks like its time for a solenoid kit.

violentsnail

Well, I think its time to resurrect this thread.

Update:
Replaced the Turbo control solenoids, specifically the TCA, CRV and CCA. Installed a Greddy profec B spec II boost controller, replaced all the vacuum lines with silicon hoses, and still I run into the same issue.

Any other ideas? I'm beginning to run out of things to replace in order to get this thing working correctly.

spoolage

iTrader: (2)

I am assuming you already replaced the turbo control actuators as you referred to as TCA? These things can get pretty gummed up and cause boost issues.

JP's 93 fd

iTrader: (28)

I don't know if anyone mentioned this but did any of you guys remove the restrictor pills. I had the same problem long time ago when I replaced the my vacuum lines and forgot to put back the pills

http://www.autosportracetech.com/RX-...rolDiagram.htm

(I didn't read the whole thread yet)