unek87

Ok guys well I've been driving my hx52 holset s4 6port for a lil bit now . And I'm trying to achieve a better ride since I'm driving it some weeks as dd if the weathers good . Well I have a fully modded s4 t2 tb that I've made work with the e6k by making a cam to drive the s4 tps . Well I'm tracking down a hesitation/ stumble at lower Rpms and bought a s5 turbo tb completely stock with tps's . So now I have a nice sweep with the oe cam and tps . I want to hook up the secondary throttle plates . But have no coolant running through my intake/ thermowax. Can I just hook up the throttle plates vacuum line instead to a vac source with the one way check valve still installed so boost doesn't close them ? . I know it may seem a dumb question and straight forward simple by sometimes we all over look the obvious
Here's a few of the old tb and new tb in hand . And the motor 😈

jjwalker

just disconnect the vacuum hose from the actuator connected to them and they'll stay open all the time. Easy and done.

unek87

I want them to work and function . Not just stay open all the time .I'd just keep my modded throttle body on instead and just swap out the cam and wide range tps of the two . I'm going to just hook to vac straight up and if the actuator rod moves I know it's working .

jjwalker

Do you you realize what those are for?

The double secondary plates connected to that actuator are only there to keep the secondaries closed when cold because mazda engineered the car realizing that most people are morons. It's there to keep you from basically floor boarding the car when it is stone cold, that's it.

unek87

I was also under the assumption that they helped decel and Low rpm step in . But I guess I was wrong and thinking of something else . Regardless I got the tps setup I needed for haltech . Thanks again for the info .

clokker

iTrader: (2)

I deleted the secondaries a few years ago and never noticed any difference.

RXSpeed16

iTrader: (41)

Look for Bumpstart's secondary throttle body modification for turbo cars. It uses the secondary throttle plates based on vac/boost as you suggest. Although, if you're having a stumbling issue, adding an independently moving linkage probably isn't going to help.

https://www.rx7club.com/2nd-generati...torque-941565/

unek87

Thanks man for the heads up . Maybe that's what I ran across awhile back . It just has this slight stumble jerk out of boost that I'm trying to solve so I figured a semi stock tb might help instead of the modded ported tb I have now . I'm going to look up bumps threads and find it

Edit thanks for the link. And just to clear up its a street ported 6 port with mazdatrix templates, not just a stock 6 port

RXSpeed16

iTrader: (41)

That's a LOT of port area, so keeping the port velocity up is a good area to attack. I'm curious if the secondary throttle plate modification helps. Your results may motivate me to finally do this myself....maybe...

unek87

Well after some reading I think I'm going ahead with how bump explained with running vac . I got as far as removing the old tb and got the new tb mounted . I had to bend my custom solid metal turbo oil feed line out of the way of the linkages . Guess my modded s4 t2 tb is packaged a lil different . Also have to make a new throttle cable bracket for the different angle the tb wants compared to the old one . Hoping by the end of the week to get it all squared away . Also working on my buddy's turbo vert he just got ,which is taking up some of my time .

unek87

Well I got this all hooked up and running . All I can say is I feel doing this has helped me all around in different areas . For one it's easier to start cold and hold its idle now . In traffic throttle is not jerky like its always been . The low end really did come up also . Fuel trims also leaned out a lot in the low rpm before getting into boost which is nice since I'm battling rich fuel maps . I'm going to up date in a few weeks when I get the tune dialed in more . And I'll do a back to back testing with and without vac hooked up to the plate

Aaron Cake

iTrader: (1)

You've got it covered at this point but as you have discovered, the tertiary throttle plates make a big difference with large port area. Keeping them close until boost helps idle, light load, etc. It's something that several years ago I started doing and haven't looked back. In fact the FD throttle body I have for my Cosmo has a NEW throttle vacuum actuator just for this purpose. Keep the port area at an absolute minimum at light load.

If you haven't already done do, using the BAC with the Haltech will give you a MUCH better cold start and idle. You can ditch the cold start cam stuff and just use the BAC as the Haltech gives you control. But don't remove the dashpot because I don't believe the E6K has a dashpot function.