I still have not been able to get my S5 T2 to run. The last thing I did was I removed the remaining emissions.

Does the Duty solenoid valve(turbo boost pressure control) need to be hooked up or not? One place I read said that it did not then I read another post that said it did. The post that said it wasn't needed said that the after market control valve takes it place. If that's so, does the plug for the turbo boost pressure control need to be hooked up?

It would sure help if people would stop selling me parts that they know do not work. A guy on here sold me a $275 ECU that I know that he knew it was not working.

 

The wire form the turbo boost pressure control solenoid goes to pin 3R on the ECU. Should this wire be tied in some other place if the boost solenoid isn't being used?

 

leave it plugged into the harness electronically. mechanically, you dont need it plugged in.

leave the hoses disconnected.

 

If it isn't really needed, what was its intended purpose? How can an after market controller take its place?

 

are you serious?

 

you would be suprized to find most sensors/solinoides,ect are not required for the car to start and run. granted it will not run real well, but would run and u could drive it around the block easily.

things required for it to run fuel pump and coils, ecu,afm, cas,injectors pluged in.

the car will start and run with no tps, boost sensor, or ecu temp sensor( tho this one might make it not start when its cold out ),or air temp sensor pluged in.

car would go limp mode with no omp also but would start and run at least.

if the car doenst start after emissions removal id check those main sensors are pluged in and the 2nd set of sensors i listed also. and check for vacume leaks? did u install a new lim to upper intake manifold gasket? or is the old one good? check for vacume leaks?

 

no do not connect the wire to anything else it could fry the ecu. you could leave the sensor pluged in, or leave it unpluged, but u would get a check engine light with the sensors unpluged.

 

still, no answer to the question about what the duty solenoid does......what does it do? why is it even on the car if it is not needed? is it pretty much a mechanical boost controller that cannot be adjusted?

 

its in the original post.

 

What???????? Of course I'm serious, do you know? I never said I was a mechanic. I just like to get a non-running 7 to run. I've had really good success over the last 4-5 years but not this time.

 

ah wasnt directed towards you.

 

It is a standard 2 port "bleeder" style electronic boost controller that most turbo engines use from the factory. There is a T in the wastegate line that connects to the boost pressure control duty solenoid. The duty solenoid bleeds air out of the wastegate signal line according to control logic from the ECU. Most OEM boost controllers work this way, using a 2 port solenoid in various plumbing configurations: Evo, STi, SR20 Sylvia/240sx, 3000GT/Stealth, Eclipse/Talon/Laser, FD Rx-7 & Cosmo, Supra, 300zx. Here is what Mazda has to say about the S5 boost control system:





The other style of electronic boost controller is a 3 port solenoid. This is used on some OEM applications (Porsche 944, Nissan R35 GT-R, GMC Syclone/Typhoon) and is used on almost all aftermarket electronic controllers. The 3 port solenoid rapidly cycles between allowing the air to flow to the wastegate and blocking it. This style of solenoid is similar to a lot of emissions solenoids you find in the rat's nest.

So here is a 3 port solenoid at rest, allowing air to pass to the wastegate:



here is the solenoid energized by the solenoid driver, blocking pressure from flowing to the gate and allowing pressure in the gate to vent out:

 

diagram from the s5 service manual I believe. on the FC you have a T on the compressor housing which goes to the bleeder solenoid. On the FD you have two ports on the actuator itself, and the bleeder solenoid connects to one of those ports.

 

I have an s5 tII with an aftermarket boost controller. I unplugged the duty solenoid and capped the lines. No check engine light, no problems. Tested it plugged and unplugged just to make sure and I noticed no difference.