Just keepin you all in suspense

Haha

I've been quite busy these last few months. Far too much indoor sport on weeknights and hangovers on the weekend have taken their toll on my motivation to fix the problem. I think you've motivated me to finally get around to checking those rod adjustments, might have to make that my Sunday task this weekend.

You got problems with your Cosmo?

 

No, customers series-8.

Perfect 1st turbo. With the help of some "pills" it max's out at 12-psi. Then drops to just 5-psi on 2nd turbo

However, whats different to your problem. If I remove the hose to the wastegate so the actuator never get the chance to pressurise, the boost still ramps to 12-psi & drops to 5-psi when the 2nd turbo kicks in.

Vacum tank stores 20" of Mecury perfectly when boost comes on. Pressure tank stores the 12-psi from the 1st turbo then drops to 5-psi when the soleniod switches the signal to the 2nd turbo actuator. I suspect this is normal as the actuator consumes 7-9 psi to travel full scale.

Tried all the regulars such as the soleniod control box (S8 gets this over the rats nest from the S6), Various 1-way valves, swapped 2nd turbo actuator. MAP sensor, ECU etc etc.

Truly, this one has scored a win against me.......

 

Hmm, have you positively figured that the TCA is receiving both pressure and vacuum during switchover, and that the hoses to it aren't crossed?

Does the TCA move in/out when doing the KOKO test?

Dave

 

OK,. I'm not American so am not into this abbreviate everything possible routine.

I'm guessing the TCA might mean "turbo control actuator" but I have no idea on KOKO.......????

The 2nd turbo actuator is getting 20" of Mercury & 12-PSI of pressure during swicthing. I have mechanically actuated them by generating vacum (have a MightyVac) into the storage tank & giving power to the soleniod with a mate under the car to watch the actuator travel. I then did the same by generating pressure (all hail the MightyVac) into the storage tank for the same result once switched.

If the hoses where switched then the above test would have failed.

The boost gained a small amount after changing the map sensor but I suspect thats a red-herring. So I am really scratching my head over this one. Naturally I have checked for any fault codes & unfortunately there where none. Must have read threads for over an hour after searching for "Boost" issues too.

 

Yep, TCA = turbo control actuator.

Well that should be sufficient to prove the TCA is moving.

The KOKO test is a less invasive test specified by Mazda: http://www.fd3s.net/boost_test.html (the section in all caps). It pretty much requires all systems to be working perfectly to pass this test.

Dave

 

KOKO = Key on Key off.............. Strange method that..!!!!

Anyway. Found & fixed it

The reason why I was unable to find any fault in the turbo's or the switching was becasue there was no fauilt.

The boost issue has turned out to be a collapsed rear muffler blocking flow. I dropped the exhaust to run on the front dump pipe (no Cat or system) & took it for a spin........ Oh yeah

Fitted CAT section & still worked, so its the rear muffler (standard exhaust). I have seen this before on some 92 models but this is a 99 so I just didn't suspect until now.

Scared myself too when boost clocked 15-psi on the 2nd turbo. Hope I didn't hurt them after that brief squirt. Customer will now be a "happy chappy" getting a working RX-7 back into his garage.

.

 

Nice work on the troubleshooting. Perhaps if I pulled my finger out I would find my solution sometime soon as well

You've just listed a few of the TCA tests that I've been planning for some time.

My rear muffler (stock) has some loose material in it, I could hear it rattling a little when I had it off a few months ago. Perhaps mine is also blocked, although I doubt it (or a clogged cat for that matter) would be responsible for just 7psi on the primary turbo at low rpm.