rotarybeat1287

iTrader: (16)

Hey guys,

I have been reading several threads and write ups on the throttle body mod for TII's. I am just wondering if my symptoms w/ my car can be resolved by doing the "right" version of the TB mod?

I have an S4 TII w/ a Racingbeat RevII turbo-back, GReddy fmic kit, GReddy profec-B boost controller, S5 turbo w/ ported waste-gate, and an Rtek 1.5 ecu.

After my fmic install was complete... we noticed that my idle was high, around 1500 - 2000 rpms. Well, it has been since and its been months now. My car has seriously barely beat what it is supposed to supposedly walk over. A mild modded GSR integra was only pulled by around 2 cars in 4th and 5th gear. So yeah, I've heard it a million times that my car should be faster and I should be able to play around w/ Mustang GT's and 350z's, etc. It seems to just creep when building boost and seems to level off power wise around 4000+ rpms.

But up until the other night. I didn't really feel it so much. Here and there my car will idle @ 800 rpms and when I lay into boost it would shoot straight to 10psi and hold steady (what I have it set to). Almost no lag and it comes in WAY harder than what I'm used to. My blow off valve would pop off super loud and my car had a very healthy "in the seat" pull that was strong up until 6500 rpms. I could really hear the turbo spooling then as well. This would only last for a couple of pulls and then it would go back to the previous state like it was only running 1/3rd its potential. It felt like I could seriously play w/ a 350z or Mustang GT then and not worry.

Well... I know that the coolant line that runs from the block to the throttle body broke when my fmic was being put in... replaced it and it didn't help my idle issue. I am wondering if removing the secondary butterflies would help me get the potential my car should be driving at. Like for instance keeping the dashpot and thermowax to keep the driveability good. But I'm a little cornfused... lol. I know its something really simple and stupid but I wanted to post this to get some info before I go ******* w/ the TB mod and regretting it.

But in theory it seems like something related to the butterflies isn't working and then it works after the car is up to temp but only for 2 pulls or so every so often. It is a very noticeable difference and complete night and day result in how it pulls in boost. I'm not quite sure.

If you guys have any input then please share! Thanks! The only reason I have posted this is because I'm finding so many different things related to the TB mod and very different out comes from doing the certain versions and extent people take when doing them.

-Allen

solareon

iTrader: (1)

if your secondary throttle plates aren't opening then that might be causing your issue. Take of your tb elbow and look to see if they are closed or open.

If you do the TB mod though just remove the secondaries and nothing else.

arghx

iTrader: (3)

Let's talk about how the turbo double throttle system works for a second.



I have taken the diagram of the n/a double throttle system from the training manual (page 4-27) and modified it a bit. First, assume a cold engine. When vacuum is applied to the double throttle diaphragm (which is on the front of the TB, towards the headlights), the set of No. 2 secondary throttle plates are held closed. You can verify this with a hand vacuum pump, and I have done so. The vacuum comes from the intake manifold and goes through the water "thermovalve" before it reaches the double throttle diaphragm. The water thermovalve gets its vacuum source from the bottom nipple of the rear of the UIM. A check valve is installed in-line so that it never sees boost.

The coolant hose on the rear of the TB supplies coolant to the thermovalve pictured here (as well as the "thermowax" which is for the fast idle system). According to FSM page 4B-63, when water temperature reaches 140 F the valve will close and vacuum will be cut. On the FD, the double throttle vacuum is controlled by the ECU through a solenoid valve, rather than being mechanically controlled.

Remove the TB from the vehicle. Rotate the throttle linkage. You should see the set of No. 2 secondary throttle plates open shortly after the first (front) set opens. If that is in fact the case, there is nothing wrong with your double throttle system and it is not the source of your problem. The only thing that could be wrong would be a messed up thermovalve or something. In that case you can just cap off the two nipples and be done with it. No vacuum would ever reach the diaphragm and your double throttle system would be effectively bypassed, although the No. 2 secondary plates would remain in place.

You can still remove the No. 2 secondary throttle plates, but if they are opening smoothly I do not believe that this is the main source of your problem. I have personally put down 386rwhp with a completely stock TB hooked up in the factory way (see attached dyno sheet).

It is highly likely that the source of your problems is an air/boost leak of some sort. There are a gazillion places it could be leaking. You must pressure test to locate boost leaks. A visual test is not sufficient! I cannot stress that enough. Just the other day a local guy came over to my place and I was looking at his 10AE. He was telling me that he checked everything with a smoke machine (which doesn't put the system under much pressure) and everything was fine. Well I hooked up my pressure tester and the TB o-ring and IAT sensor were leaking. We removed his TB o-ring, cleaned out the groove, and installed an o-ring from a spare TB I had. Then we removed the IAT sensor, cleaned the threads, and put a small amount of blue RTV on the threads. Blue RTV works MUCH better than teflon tape. I hate that crap.

Here is a boost leak tester:



http://www.boostpro.net/prodtester.html ("universal tester" at the bottom) . It can easily be made out of home depot parts as well. You may need an adapter coupler to hook it directly to the turbo inlet (AFM removed) or I believe a 2.75" adapter to the Greddy TB elbow if you choose. If you don't have an air compressor at your house, get the pressure tester with the tire valve adapter and take it to a gas station. When you pressurize the system, feel around for air escaping. Spray slightly soapy water all around and look for bubbles. The vacuum hose you are using on most nipples should be 3.5mm or 5/32" and you should check to make sure that no vacuum caps have cracked.

rotarybeat1287

iTrader: (16)

Thanks a lot man. That was a lot of helpful information! Yeah I'm going to look into checking for boost leaks but one quickie if you don't mind?

If my secondary throttle plates open smoothly then are you talking about capping off the upper 2 vacuum nipples on the UIM and leaving the 3rd one intact? Thanks again for your reply and hopefully I'll fix this soon enough.

arghx

iTrader: (3)

on the s4 T2, you could run the primary air bleed to the top nipple there (pictured as secondary air bleeds in this pic), then OMP in the middle, and the bottom one to the boost gauge or capped. some cars do have 4 nipples on the back of the UIM, and I'm not entirely sure what to do with that 4th one.

rotarybeat1287

iTrader: (16)

Took my IC pipe and elbow off to find that my secondary throttle plates do in fact function. Capped off the thermovalve vacuum lines and then re connected my bov vacuum line. Car feels amazing now.

Good strong and hard pulls in any gear. I have it set to 8psi right now and man it feels like it should. My bov pops off super loud and I cannot be happier that my FC feels twice as fast. Car takes little effort to get up to speed now.

I guess its safe to say that my thermo valve was non-functioning?!?!? lol. But yeah, thanks for the help and replies! My car feels awesome now!

arghx

iTrader: (3)

if it was in fact a bad thermovalve, it would partly explain why Mazda ditched the thermovalve on the FD and used an electronic solenoid valve instead:



If that system fails, most likely the car would still drive normally and you wouldn't even notice any problems.

iamxeddiex

iTrader: (1)

I have an 87 s4 n/a, and the thermo wax is bad. I want to do the tb mod because of this. I would like to keep the bac valve and cruise control. What would I do with these two hoses?

need RX7

iTrader: (4)

I have a new hose running from the BAC outlet to the nipple on the rear iron. Essentially connecting those 2 hoses together, bypassing the thermowax.

iamxeddiex

iTrader: (1)

I thought that would it thank you so much, need rx7.

arghx

iTrader: (3)

The BAC valve does NOT need coolant running to it at all unless you are in a very cold climate. The coolant is mostly to keep the valve from freezing up. You can leave the coolant barbs completely open.

iamxeddiex

iTrader: (1)

I just wanted to know what to do with the two hoses.

Hypertek

iTrader: (3)

I removed the secondarys, removed the shaft and shaved em, looped the water lines, and ported/shaved the whole thing.. Works great, only thing is starting the car sucks, any solution to that with the parts i removed?

rotarybeat1287

iTrader: (16)

Holy ******* thread resurrection... That was a long *** time ago. lol. I've already done the TB mod and yeah, starting the car sucks but it's not bad after taking it down the block.