pyscho7

so since ive owned the car (3 months) ive had boost issues. the turbo can spool to 7 psi, but it has to be in 2nd and above gear, and it has to be floored. but occasionally it will boost properly, and hit 7psi like its supposed to and it will creep a little at higher speeds.

Mods include: RB exhuast, 3" dp, SAFC, blitz intake/bov, 720 sec, 255cfm walbro, and a couple other doodads

i pulled off the turbo tonight to check the switch valve and i really wanted to get a closer look at all of it. and this is what i have found out. it works, like when i took it off, it was in the right position. but it hard to move it around but did not have trouble staying open.. but it would make sense for it to be closing off one of the ports on the turbo because when the car doesnt hit 7psi properly it is also making about 30% less a/f according to the safc(normally no higher than 50%, occasionally when working right 77%), which judging by the port sizes on the s4 turbo, the one the switch valve closes off is about 5/6 the size of the port that remains open at all times.

What i dont know is if the switch valve is bad and/or causing my problem with boosting. because i have checked a lot of things and i have two videos of the car accelerating properly and it not accelerating properly to demonstrate if anyone would like to further up and GIVE ME A HAND!! and maybe help me figure out what i can do to check out why i am not boosting correctly. i'd hate to say the injectors dont work b/c the gas mileage is crappy as all t2's are, but im missing a good bit of performance. I checked the turbo and it is in great shape as well. and the wastegate works properly also.

Can i just remove the switch valve? or is this a bad idea?

ive tried asking similar questions before and no one replied or answered, i guess they wanted me to be where i am today, which worked out for the best because i have found out a lot more about the car.

NZConvertible

The twin scroll system is fail-safe, meaning if anything goes wrong with it the flap stays open. Low-rpm lag will be worse but max boost and power will be unaffected. The only way the flap can stay closed when it's not supposed to is if it's been replumbed incorrectly. Is the stock solenoid rack still in place or has it been removed?

pyscho7

i am not completely sure where the solenoid rack is unless there is another name for it. i looked in the haynes and it says nothing. and i pulled up a search on it, and all people do is mention it. could u tell me where it is and i will check it. also what do you mean by replumbed incorrectly?

i have heard about some waste gate pre control solenoids that are connected to the ecu, i am assuming they can open it up early? i probably need to check these also. but again dont know where they are, all i heard someone say was they were by the intake on the right side.

i just dont know why i am missing so much of my power majority of the time. it has to be a connection, valve, solenoid, something sticking. and i really feel it has to be something to do with that switch valve or the wastegate because i dont know why else i wouldnt be driving around boosting abnormally with a good turbo.

HAILERS

Well to eliminate any possible problem with the plumbing.............just follow the hard vacuum line from the twin scroll actuator til you meet the soft vacuum line that connects to it. Then pull the soft vacuum line off and plug it with a stud/bolt/use your imagination.

Now the thing will be OPEN all the time and NEVER close. Go drive it for a few days. If your problem persists it isn't the twin scroll actuator/solenod/checkvalve/vacuum line/whatever. It's another thing all together. There IS NOTHING ELSE that controls the series five turbo other than the wastegate actuator and it's hoses.

pyscho7

its series 4, but i will try that, i am cleaning up a few things while i got it all apart, i will try this plugging the twin scroll, i hope this works because i miss the power that only comes so often.

HAILERS

I meant to say "series four turbo", NOT "series five turbo". My bad, so to speak.

NZConvertible

It's the assembly of hard vacuum lines and solenoid valves sitting on top of the engine. The solenoid valves have coloured plugs.

I've only heard of the twin-scroll system reducing power once, and that was because the owner removed the solenoid rack and tried to replumb the twin-scroll system to keep it operational, and got it very wrong. It you don't know where the solenoid is, it's unlikely you've done this.

Not on your car. Only S5's have electronic boost control.

The only way either the twin-scroll actuator or the wategate actuator could have any negative effect is if one of them has fallen of it's respective linkage, allowing the flaps to swing freely. This is very unlikely but it might pay to visually inspect them anyway.

Are you sure the turbo's good? No leaks in the IC piping? Ignition timing not messed with?

pyscho7

we have already had it reset, "professionally" but the timing is good we'll be checking it shortly, the linkage is all good, the turbo is in very good shape, solenoid rack made sense when i went outside tonight. i installed the two l.e.d.s to pull codes as i am driving to the 6 pin connector, but i think i am close to fixing it, i work and go to school as well as fix the rx7 and i am usually a little short on time. i have several things i will be doing as i put it al together, cleaning up including injector connections, replacing the IAT, fixing a couple kinked vacuum lines, kinked coolant hose, two intake hoses, also check all the solenoid plumbing,