93_jdm_fd

iTrader: (1)

I have been sitting in this chair for the last week searching for and answer to this problem. I have had confidence everytime i read some bit of info that makes sense and run out and check my car. I have probably over a million turbo parts lying in my garage and have changed out solenoids, CRV's and all the rats nest hoses have been changed with nice viton hoses and zip tied.

Anyway my boost pattern from 3rd gear to WOT is 11-12psi to 4200-4400rpm then boost drops to 0psi. It's like my secondary turbo is doing nothing. I did read about the double throttle not being working properly will cause boosting problems. I have the connector on the rack plugged in but vacuum hoses disconnected and the line on the dash pot thing plugged. Could this be the problem?

I know there are probably alot of people with the same kinda problem so please if you have fixed it let me know what you have done.

RotorDream

its amazingly technical terms like this that make this forum so efficient
if your even considering that the dashpot could in any way what-so-ever be related to your boost problem at wide open throttle you have seriously misunderstood how the twins work. you should read up on how the sequential system works first.

93_jdm_fd

iTrader: (1)

I know enough that at 4500rpm the secondary turbo is suppose to prespool then within seconds be at 10psi and it doesn't.

There are a million technical terms for these engines so sorry I did not get it right, but most people that read it will understand what a meant.

I did read that if your double throttle is not working properly it will hold the throttle plates closed. Then another post says it does't matter. So this site is filled with all kinds of misguided information.

jmadams74

OK, so you provide sketchy information, then trash the site that might be able to help? In spite of all that, I'll take a shot at it. . .Sounds like perhaps at transition your charge control valve is opening as it should to allow secondary boost to come on board, but your charge relief valve is not closing, thus all boost is being allowed to escape. Just a (reasonble) guess. There is lots of very good data/information on this site relative to twin turbo operations, and of course with thousands of posters you will sometimes get conflicting information.
--Jeff

Mahjik

iTrader: (1)

This will give you an idea of what is going on around that 4500 rpm mark:

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

One thing you can test is to force the CRV closed all the time for testing. If you then have boost after 4500 with that forced closed, then you know that's your problem.

jhaywood

I had a similar boost signature, good up to ~4400rpm, then dumps to no boost - My secondary turbo was shot, with fractured casting in the turbine stopping it rotating freely.
Troubleshooting this, everything looks as it should be working. I ended up pulling the inlet to the secondary turbo & seeing if the turbine rotates freely (mine didn't, hence no boost!).
I would recommend you do this, it is pretty easy, just pull the inlet hoses from the airbox & undo two nuts
holding the inlet pipe onto the turbo. Takes about 30 mins or so to do this.
Check the turbine rotation is nice & easy, if it is then you know the problem is control & not the turbo itself.

RotorDream

Thank you for proving my point. There is a lot more going on than at 4500 God says let there be boost! The process actually begins at idle, when the vacuum chamber that runs the system is charged with vacuum. Read the thread Mr. Links posted about how the system works, and educate yourself. Yes, there are a lot of technical terms having to do with these engines (a hell of lot more than on a piston engine), but through the FAQ, reading through the forum, and the search feature, most of us here have learned the majority, if not all of the sensors, actuators, solenoids, and valves that are involved with at least the turbo system. This is one of the most complicated systems on any car on the road today, you better have a good understanding of how it works before you start switching out valves/sensors.

What this forum is filled with is peoples opinions and experiences. This is one of the main reasons why you need to have an understanding of the systems before you try anything. What worked for one person may blow another's engine. I can guarantee with any doubt, that there is more collective knowledge about every possible aspect of this car here than at every single Mazda dealer in the country. So like madams said, you should really think twice before you downgrade the one site that will probably prevent you from destroying your car from ignorance.

93_jdm_fd

iTrader: (1)

I'm not trying to bash this site at all. I have limited knowledge of how this engine works. I have read and read alot of info on this site before i even post anything. I have done a massive amount of work to this car and it's my daily driver. It hasen't let me down at all.

I just don't know all the terms of what things are called and am not being ignorant. I have learned alot form this site just it's turbo trouble time and it seems alot of people have alot of problems. I just have been sorting through it all and figured maybe someone had the same problem and they fixed it.

Today i found vacuum line cracked on the charge control actuator. I replaced the hose and haven't had a chance to test it out. I live in the city and it's almost impossible to find anywhere to get up to 4500rpm without getting a radar ticket...

I have a route that i take in the morning to test things out so i hope it fixed.

MOBEONER

iTrader: (18)

Go non sequential. to tell you the truth even if you get to fix this problem something else will fail.
I was trying to keep my twins sequential but i have spent more time fixing the vacuum gremlins than i drive the car. just my opinion.

M104-AMG

iTrader: (8)

It took me about 6-months to chase down everything, but for the past 3-years, I've had no issues with my sequential system.

Keep it.

:-) neil

93_jdm_fd

iTrader: (1)

Alright so i found the problem..... I had two ABV's!!!! These valves came on the car since i bought it and i didn't realize. I haven't really had a chance to drive it hard so i never really noticed until i drove another FD and felt a huge difference in power.

So i swap in a CRV and now i can so both are spooling and working the way they should be. i still have a few questions though.

What check valve should be coming from the vacuum tank? I have in there now a little white and green valve pointing to the UIM. My friends car has a big green and black valve pointing to the UIM? Which should i use?

"Double Throttle Control

* This keeps a second set of Secondary throttle plates in the throttle body closed. If the Double Throttle control is not working properly, (i.e. secondary always closed) then maximum boost will be restricted to ~5 psi."

I found this info from autosportracetech.com. I have my double throttle solenoid plugged in but I have the actuator vacuum line plugged off and the one from the UIM plugged off also. I did not remove the plates though because other info said just simply plug off the lines and be careful to rev the engine when cold. So what is the proper way to disconnect it?