Ok guys,i am in a dead end.My transition sucks,from first gear to fifth its the same 10-5-10.I searched,but i could find a clear answer.I "managed" to isolate the source of the problem(i think so).According to autosportracetech site,if i turn the engine off,the KOKO sequence should make the TCA work each time(and the CCA).Well,my CCA works,but not the TCA.The steps i followed:

Replaced TCA.
Checked both solenoids for turbo control either hot or cold both ok.
Pumped Vacumm and pressure to the equivalent pipes from the rats nest,TCA moves.
Pressure chamber ok.
Vacumm chamber ok.
Check valves hold pressure.

In other words,i am running out of options,so any suggestions would be helpful.

Stathis

 

why do you care that for a split millisecond you get 5 instead of 8? i wouldn't think it'd be noticable drivability wise?

 

Because it's more noticable than you think.

 

I think you should dig a little deeper into testing the tc solenoids. Take a look at Dave Disney's pressure test for the solenoids.

http://rx7.voodoobox.net/howto/solen...oid_check.html

Since the behavior is consistent, you could also try teeing into each line between a solenoid and actuator, and using a separate pressure gauge, see if one is releasing and supplying at the proper time. If a solenoid is not working right, you'll see it here.

Dave

 

Yep,i checked D.disney site,no luck.Only thing left to do is the "teeing method".....

 

Ok i need a favor.Can anyone with the help of a friend crawl under the car and see if the TCA moves in and then out during startup?

 

When you tee into the secondary turbo you should see it spool up before 4500 rpms if precontrol is working.

At the Charge Relief there is a small vacuum hose behind the 1" hose that bends 90-degrees. Tee a test gauge on the small line behind that 1" hose.

You should see no activity until 3500 rpms where it should roll up to roughly 8 psi by 4500 rpms. Over 4500 rpms it should read 10 psi.

If this checks out then you can move on to TCS. If not then maybe there is a wastegate problem. I need to review the diagram more to go from here, but this should give you time to tee the above test.

 

Well,here are the results from the "teeing method".


3000.......4500.......6000 RPM


CCA CHAMBER A -10 0 10 PSI

CCA CHAMBER B 10 5 10 PSI


PRECONTROL SOLENOID 6-8 PSI AFTER 4000 RPM

TURBO CONTROL ACTUATOR(PRESSURE) 2-4 PSI AFTER 4000-4500 RPM

TURBO CONTROL ACTUATOR(VACUMM) 0 - (-2) PSI AFTER 4500 RPM


So,what you guys think?

 

TCA Vacuum Solenoid should give you max vacuum (-10psi) immediately at 4500rpm. The TCA Pressure Solenoid should give you max pressure (10psi) immediately at 4500rpm. Both appear to be lazy. This could be the solenoids (these two are known for more frequent failure than the others) or the pressure and vacuum supply.

Tee into the pressure and vacuum systems between the tank and check valve and do road tests to see that full vacuum and pressure are available to the solenoids. Those are the values you should immediately see when the TC solenoids open at 4500rpm. You should also see the vacuum and pressure levels remain high throughout boost/decel. If either system is leaking, it could be the check valves leaking, (more likely), damaged/popped hose (more likely), or one of the solenoids leaking (less likely).

If that is the case, then really only two things are possible: bad wiring/ECU signal (less likely) or bad solenoids. In either case, if you can afford new solenoids ($60/ea) then I suggest buying them. Once you get under the UIM to test and replace them it seems like a small price for the insurance.

Dave

 

Dave thanks for the reply.My post wasn't clear enough.Both give immidiate vacumm and boost at 4500 but then there is a fall to 0 psi and 10 again.As for the wiring i also don't think so,i have no error codes.I also teed the vacumm chamber and pressure chamber,both behave normally(And the check valves hold boost forever).BUT listen to this:I unplugged the TURBO PRECONTROL SOLENOID and wtf!!!!! 10-6-10 in first gear and 10-8-10 in second and third(WOT from 2000 rpm).WTF????????(and still the tca doesn't move during koko).

 

I studied the diagram, and indeed it suggests the TCA arm should cycle, as long as the pressure and vacuum systems are fully charged and the solenoids are receiving voltage during Key On (I'll get to that in a moment). The KOKO test says to wot in neutral immediately before the test, presumably to charge the pressure tank. I do believe that some cars create more pressure than others, so if you're not getting 4-6psi when you punch it in neutral, there won't be much charge in the pressure side. But the vacuum alone (7+ psi vac) should be just enough to move the TCA visibly.

With the key off, the solenoids are switched off. This connects the front (vacuum) and rear (pressure) chambers of the TCA to atmosphere. To see them move each KOKO, the solenoids would need to be on during IG:ON (engine not running), then off with IG:OFF. According to F-183 of my FSM, only the charge control solenoid turns on during IG:ON. The TC solenoids do not. So according to the documentation, the KOKO should cycle vacuum through the CCA, but the TC solenoids should remain closed and the TCA will not move. This suggests the Mazda Pleasanton KOKO process has an error regarding the TCA motion.

I am curious myself, and if I have the chance to test the electrical signals I will. I'm still leaning toward bad TC solenoids. At 4500, each solenoid should supply full vacuum or pressure as long as you stay on the throttle. TC solenoids wear out sooner than the others or exhibit sticking problems that can be hard to test for. So in that sense, installing new ones is a preventative maintenance for your turbo controls.

Dave

 

dave thanks for the reply.Yesterday i've replaced the TC solenoid(vacumm),and in a couple of days i'll do the same for the other TC solenoid.As for the 4 psi,i can get 4 psi in neutral "easily".I wont quit,i 'll find the problem and post the solution.

Stathis

 

Does your TCA hold pressure and vacuum without leaking?

Oh, and I don't know offhand what the precontrol issue is doing. I would expect that would make transition worse, but oh well - it doesn't help to try analyzing two problems at once.

Dave

 

I read deeper in the FSM, and in the ECU code troubleshooting list (page F-56 or thereabouts) it describes the signal to each turbo control solenoid as B+ (12v) when Ignition is On. That certainly makes sense, since the ECU can then attempt to detect each solenoid and throw codes if there is an open or short. F-183 then appears to be in error regarding teh TC solenoids.

I suspect a sticking solenoid will cause the TCA to not move.

Dave

 

*update*.

I tested the wiring harness going to the ecu.I grounded all 6 solenoids(2 tc,precontrol,wastegate,crv,ccv),and all clicked when grounded.I removed(again)the UIM,pressurized the solenoids up to 15 psi,heated them with a heat gun,and all released quickly(Vacummed the TC solenoid).
I've checked again the pressure chamber and vacuum chamber,and both hold strongly.I 've also checked the silicone hoses for cracks,all perfect.I've even replaced the hose coming from the precontrol actuator(the one with the pill),and replaced the precontrol solenoid althought it was working.

Finally,tested again ABV and CRV,both passed.

In other other words,i am running out of options....There are two facts althought.

1.The TCA doesnt move in-out during startup.
2.If I unplug the precontrol solenoid i get an almost perfect 10-8-10 but after 6000rpm boost creeps even with the boost controller.

I also unplugged the profec and returned to stock wastegate control,but nothing changed(except a 12 psi spike lol).

I think that the last thing left to do is to adjust the control arms,but i don't think that its the source of the problem(i've checked them,are in proper length).What puzzles me is this:

https://www.rx7club.com/showthread.p...em+restrictors

"However, if it drops to 5 but then build right away it probably is your turbo precontrol actuator. It sppols up the secondary before it comes online, so if it is not fucntioning you get a huge drop at transition, but immediately starts to build. Test its selenoid, and plumbing for proper operation. this is were the pill comes into play and why it was mentioned earlier. everythign that was said is true, but you do not need aftermarket needle valves. the build delays the build up of boost in the actuator. the greater the pressure in the TPC actuator, the more it robs from priumary to pre-spool the secondary. the pressure is vented by its selenoid which is the upright selenoid to the left of the WG selenoid. Make sure selenoid works by slapping 12 volts to it. then take off the line from the TPC actuator to the primary turbo, and stick some pressure on it to make sure it moves. if some of these things do not happen you know where you problem is."



Very soon i'm gonna remove for the 30th time the UIM(in 10mins max) to replace the spark cables,so any ideas for my problem would be welcomed....

 

I have the same 10-5-10 boost issue, and it is indeed very noticable.

I am still waiting for my mityvac from cars_and_tools eBay seller, which I paid on 22nd of March and I suspect it wont show up, to diagnose what is going on, so I will keep an eye on this thread.

Good luck.

 

I just noticed you say you have a profec installed. I had the same problem after installing my profecB. Here's what I figured out....
Because the boostconstroller controls the wastegate independently of the ECU, it opens the wastegate more below 4500 than the ECU would. This ECU primarily uses the Precontrol to manage boost between 3000-4500rpm, and the wastegate stays mostly closed.

The boostcontroller doesn't know anything of the sequential setup, it simply opens the wastegate to maintain certain level of boost pressure. The result is that more of the exhaust is bypassing the turbos completely below 4500, effectivly reducing the amount of exhaust pressure available to spool the secondary turbo prior to transition. Basically the opening of the wastegate by the controller is robbing energy from the prespool of the secondary. To counter that the prespool door needs to be opened further. This can be accomplished by switching to a larger pill in the line from the compressor housing to the prespool actuator, or installing a needle valve, or a number of other ways....

I installed a needle valve in the line to the prespool actuator and used that to adjust the transition... My transition has gone from 10-6-10 to more of a 10-9.5-10.5-10. It is very quick now. The very noticable drop in accelleration is replaced by accelleration followed by even more accelleration

I would try this first before tearing even more apart only to come back to this.
Hope this helps.

<edit>
Just thought about this.... Do you have the restrictors in the nipples like some of the 94-95s do? If that's the case, I think you could install another restrictor on the side of the actuator that goes to the solenoid to achive the same result (more pressure on the prespool actuator).
</edit>

 

This was an issue on a friends car. Turned out to be a split hose on the actuator at the y-pipe that brings on the secondary boost. It kept getting lazier and lazier. It wasn't hard to replace and there was tell tale oil/dirt residue around the split in the hose but you couldn't see it till you took of the fatory BOV and the CRV. I'll see if I can get you a picture of the area. Jack

 

Guys thanks for the replies,but nadda..Even with the stock wastegate control i have the same symptoms-boost pattern.As for the hose to the y-pipe that goes to the cca,i checked it,its fine.
On another note,i visited a guy with a bone stock Fd.I noticed that during the KOKO test the TCA doesnt move,but The CCA goes in-out-in rapidly and stays in,while mine goes in and stays in.Also during startup,his TCA goes in-out in contrary to my TCA which doesnt move at all(during startup).
That thing becomes more and more complicated........

 

*Update no.2*

Today i replaced 3 solenoids(TCS,CCS,TPC) with some 99 spec i had(i had to ghetto modify them to fit in the plugs).Results?same 10-5-10.

BUT

As a friend suggested,i removed the pfc and installed the stock ECU.Guess what.The boost pattern went to 10-7-10 AND THE TCA IS WORKING DURING KOKO TEST WTF!!!!!
In other words or the PFC has a problem,or it is programmed by the factory to not to execute the TCA check............

So my question is:If we suppose that everything is ok,do i have to mess with the PFC boost settings to achieve a 10-8-10?

 

"PROBLEM" solved!!I lowered the values for the primary TC in the boost section of the PFC,raised the values for the wastegate control in the profec,and everything works perfect...

 

Congrats - that thing should run like a champ for a long time now...