christi

I'm sure this has been said many times - but unfortunately I can not find it in the search part of the forum, it keeps giving me an error. I was wondering, after the TB mod, are there any other changes you need to do to the engine or car itself? Any significant change in it? I do know that after you do the TB mod, that it's harder for your car to idle at cold starts - is there any way to prevent that after you're done?

88IntegraLS

Hi,

I used to get tricked by that error message after doing a search, too. Ignore it. After about five seconds, your search results will show up. I don't know why it shows that error message at the top of the screen. It goes away when the results come up. I don't think it really means much, other than some web specific anomoly that a web designer would know about

silverrotor

iTrader: (1)

Quite simply, If you are concerned about the aftermat and are worried about the adverse effects associated with the TB Mod, do as I did.

Just remove the Secondary Plates. You could even do It while the TB Is still In place. Thats where all the performance Is anyway. I'm reluctant to believe that the removal of the Coolant hoses Is that big of a gain, as compared to the actual removal of the Plates.

Jimmy325i

removal of the coolant lines just cleans up the clutter of the engine. Once the secondary butterflies are removed, the coolant lines are pointless.

Josepi

if you search for TB Mod, you'll get an error for the TB...it's two letters...just the way that the forum is. Minimum of a three letter term for search.

christi

The BAC line hose - that you need to replace... which hose extactly is that? How big around?

von

Dont know how big but I got mine from kregan. They have the same hoses thier just pic one thats the same size. I went from the engine block to the BAC out the BAC to the waterpump. Very simple.

mazdaspeed7

Dont you ever read something besides the lounge at n0pistons.com? Theres a lot of stuff there about the TB mod lately.

christi

Actually, I have not read anything there in a while - unless it was while I was toasted this weekend.

I've gone through the 2nd gen forum there, but haven't seen anything containing the TB Mod - maybe I missed it.

I am not doing the full TB mod myself, "billy" a forum member here will be doing it - and i'm giving him my TB to him when he's done - as I do the lines. I read up on http://fc3s-pro.com/TECH/HOWTO/TBM/tbm.html and understand everything.

My question starts here:



"Rear shaft hole plugged with Aeroquip 1/8"NPT plug. This concludes the modifications to the throttle body itself. You'll need to reroute the 90º coolant hose that used to connect the rear end side housing to the throttle body for the cold-start system (now removed). You can either run a hose from the engine to the BAC valve, or you can run a hose from the rear engine housing to the back of the water pump housing which will bypass the stock BAC valve. NOTE: Because of the very limited amount of space under the throttle body, you need to run a pre-formed, 90º hose. Most local auto parts stores carry preformed 5/16" hose with 90º bends. I found a hose designed for a Mopar that has a short 4" leg on one end (needs to be shortened to fit the nipple on the engine block) and a 18" length leg that can be run to the BAC valve."

What size of the hose must it be, since you need to replace the BAC line.

When it talks about the hose underneathe the TB, what size does that need to be? I'm sorry for being quite stupid, but I'm not really understanding that there has to be a 4" leg on one end, and a 18" length leg that can be run to the BAC valve - I am not sure what they mean by "leg", thereof.

Sorry.

NZConvertible

Nope, the coolant lines are still required because the thermowax operates on the primary throttle. Removing the #2 secondary throttle plates (but nothing else) means you get most of the performance advantages of the full TB mod (the shaft is still a restriction but throttle response is greatly improved), but cold-engine idle quality is unaffected.

TonyTurboII

It needs to be 5/16dia hosing. Theres 2 lines going into the TB. One from the BAC, and one from the engine block under the UIM. After you modify the TB, youll want to find(mopar hose) or construct a hose that will go from the nipple under the UIM to the nipple on the BAC.

Youve essentially looped the two hosed going into the TB.

To make it even simpler, you can run a hose from the nipple under the UIM, to the nipple on the back of the water pump. Doing this bypasses the BAC, as well as everything mentioned before. It will also cause a longer warm up of the BAC.

If you have a hard time understanding the nipple locations, I can snap a pic for you since my intake manifolds are off.

rx7_turbo2

Since the coolant does not actually travel through the BAC valve, I just ran rubber hose right from the nipple underneath the TB to the nipple on the back of the water pump, it works fine.

bob13bt

iTrader: (9)

I was pretty much forced to do this mod.....my TII idled at 4500!! Fast idle huh?! Anyone else have their fast idle stick on them?

Oh and Christi, just fill the secondary throttle shaft holes with JB Weld. It has worked great for me since I did this mod back in March. Put tape on the holes on the inside of the TB. I used masking tape. Then fill one hole completely (and slowly so there is no air trapped) and tape the other side. Now flip it over and repeat.

cblake3

iTrader: (2)

What do the secondary throttle plates do? I thought they were for cold start-up.
I have been contemplating the Throttle body mod for some time, but if I can remove the secondary throttle plates and keep the cold start-up function, I would rather do that.

Jimmy325i

the bare secndary throttle shaft causes more turbulence than leaving the butterflies in place and wiring them open. take the shaft out if you're gonna do this mod.

TunedRunner

The secondary throttle plates stay closed until the motor has warmed up enough. Unless you like to beat on your car before the temp gauge needle is off of the peg these plates are nothing but a restriction.
The cold start idle is governed by the thermowax sub assembly. I don't see any reason why you could not take the sub assembly off to remove the secondary shaft, fill the hole then put it back on. Of course you would want to leave the fast idle cam alone and you would need to leave the coolant lines running to it.
The major reason for removing this stuff is to keep the hot coolant away from the throttle body.
Might as well port the area where the secondary plates used to be while you're in there too.

NZConvertible

That makes no sense. Care to explain?

NZConvertible

The #1 secondary throttles (directly below the primary throttle on turbos, above on NA's) are opened mechanically. The primary and secondary throttles operate sequentially, that is the secondaries don't start to open until the primary throttle is partly open, but they both reach WOT together. In order to stop any hesitation or jerking from the secondary ports suddenly flowing air, the #2 secondary thottle plates, upstream of the #1 plates, are operated via a dashpot that slows their opening speed, regardless of how fast the #1 plates open. This delay in "real" WOT being reached smooths the transition, but at the expense of some throttle response. Plus the extra set of plates causes extra restriction.
As mentioned above, the #2 plates are also held closed until the engine warms up, to idiot-proof the engine a bit. Hopefully anyone contemplating this mod are also not so dumb as to thrash a cold engine...

BTW, this five-throttle set-up has been used on every EFI Mazda rotary from the '82 12A Turbo to the 20B and Renesis.

HAILERS

NZ...that was a very good explanation. Now can someone tell me just how the green check valve works in the scheme of things? You know, that one b/t the double throttle diaphram and the water thermo valve. Similar to the delay valve on a n/a, except its a CHECK VALVE. Never could come to terms with that. Seems if its a check valve, it'll hold a vac on the double throttle for ever and never.

Rpeck

DO NOT leave the shaft in!

I speak of this from experience. I left the secondary shaft in on my throttle body … everything was fine for weeks. Then I went to Dyno tune and the shaft started to work its way out a little … it got stuck on one of the outer mechanisms of the throttle body. I was doing a WOT dyno run at 8k RPM’s and I went to let off the throttle and it just kept going!!! I now know that my engine can do over 10.5K rpms. I finally hit the key just in time… but it took me 2 Hrs to take the whole manifold apart at the dyno shop to **** rig the thing to stay in. If this would have happened at 8k and WOT on the highway I would not be talking to you right now … I would be one dead SOB.

Put the plug in, wled the hole … put a piece of cork in it … JB weld, anything! Just don’t leave that rod in there.

-Robert

P.S. taking the secondary plates out kills your torque curve .. though you do gain HP … I have dyno evidence on this.

Jimmy325i

NZ, The rod exposed in the center of the TB without any direction aiding devices (the actual plates) causes an eddie on the back side of the bar. That there are holes in the rod makes the problem that much worse. Ever drag a perfectly round rod through water? It still has drag! The butterflies help cut the air going over the rod to reduce turbulence. In effect, the original butterfly rod acts as an air foil.

NZConvertible

That may well be the case, but I'd think those huge screw heads protruding into the airflow would be even worse! Either way I think the actual difference to power would be 5/8 of **** all...

However, after reading Roberts scary story, perhaps just pulling the plates is a bit risky. I've been doing a bit of thinking about this today, and I think it would be possible to remove the entire #2 secondary throttle system, but leave the thermowax in place and keep your cold idle.
Earlier someone mentioned removing the thermowax, plugging the shaft hole underneath it and then reinstalling the thermowax. But I wonder if the thermowax even needs to be removed, and would keep that hole airtight leaving it untouched. It's hard to tell with the TB on the car but from the photos on Ted's site it looks like it might work. Can someone confirm?
So basically everything on the rear of the TB is untouched, and all the #2 throttle linkages on the front, plus the throttles and shaft, are ditched.
I like my car to idle when it's cold, so I'm definitely going to investigate this.

Jimmy325i

My car doesn't idle for **** when its cold. You have to keep it above 1500rpms till it warms up or it'll choke on you immediately.

I did run the TB mod with all rear crap attached and just the front hole plugged successfully for a couple months. I waited till I pulled my motor to tap and plug the coolant lines at the block and water pump housing and pull the remaining garbage off the rear of the TB housing.

NZ, as for the screw heads causing more turbulence than big slotted recesses in that rod... No way man. Those passages left by the butterflies and the rod it self cause a hell of a problem for smooth air flow. Do what you want with your car. I'm just trying to make every 7 in the world faster.

No7Yet

I really don't know what you guys are on about. I've done the TB mod, and have removed absolutely everything but the actual throttle plates - no secondary butterflies, no cold start assist, no dashpots, nothing.

I love it. The cold idle system was causing my idle to be sporadically high, which was very irritating - that's why it was removed. The secondary butterflies were causing me to boost low. The dashpots were softening my off-throttle response and KILLING the throttle feel.

When I start my car, stone farking cold, the idle drops to a rock-solid 600 RPM. As it warms up, it rises to (again, rock-solid) 700 RPM, and stays there until I shut the car off - simple as that. The only idle assist I have is a well-tuned BAC (no AWSV or ASV). I can pull my UIM now in about 5 minutes, and what used to be the hardest part (pulling the throttle cables) is slowed only by my dumb fingers. Sure, the car's a little slower to warm up, but I'd rather have a car that takes an extra 2 min to warm up than my rotors spinning at 500 RPM stone cold. The throttle feels lighter underfoot, and response is incredible. Power was marginally improved.

There's no reason to not do the TB mod if there's something that needs fixing (don't do the TB mod "just because"), especially if you're frequently under your hood.

As Thoreau said, "Simplify, simplify."

Brandon

Jimmy325i

My street port will barely run at 650rpm.

Blap Blap cough Blap Blap cough Blap Blap

I love it, but she sounds like she's gonna die at any second so I keep it up around 750-800.