The thermowax bumps the idle until the engine warms up. It makes the engine less likely to stall in cold conditions. I don't know about the TII TB, but in the NA TB the thermowax assembly just bolts to the side of the housing and bumps the throttle linkage a bit. Since there's no coolant running through the TB and it doesn't weigh enough to matter, I kept my nice cold idle.

 

if your going to drive your car in the -temps couldnt you just have your car idle at 1k instead of the 750 as suggested? Then you wouldnt have to worry about the thermowax?

 

give it up guys, the argument is about 10 years old. basically its just personal preference.

pat

 

If you set the idle that high when warm it will still have a crap idle when cold. Engine's need a lot more air to idle cold. Plus you'd have an annoying 1000rpm warm idle...

Pull the double throttle system, leave the thermowax. Best of both worlds.

 

what does it mean to reroute the coolant hose? in fc3spro it says to reroute it to somewhere else. whats teh point in rerouteing it? if i dont take out the thermowax do i have to reroute it?

also would i have to take off the fast idle cam, if i dont take out thermowax

 

If you remove the coolant feed to the throttle body, you need to either plug both sides of the coolant feed, or just loop the line from one to another (remembering to keep your BAC valve in the loop).

If you remove the thermowax, you remove your cold start cam. But only in that circumstance.

 

If you have standalone engine management, couldn't you theoretically use temperature-based adjustments to keep your idle decent with the thermowax and cold-start cam removed?

 

Are there any disadvantages to the TB mod? I read it hurts your low end or something. Is this true?

 

The mod works extremely well. NA and T2 users alike have been very pleasantly surprised by how well the car acted afterwards (of the ones that I have done). Contact me via PM for any more details on the service I offer.

http://home.comcast.net/~bdc196/ThrottleBodies/

B

 

Supposedly the removal of the secondary plates causes the engine to stumble at low RPMs if you stab the throttle suddenly, so just learn to lay into the throttle gradually.

 

It doesn't have that effect. The accelerator pumps on the stock ECU are pretty rich; no negative effect to the removal of the secondary plates. I first removed mine in January of 1998. No ill effect.

B

 

Yep.

 

For many drivers it does add a stumble on low rpm switch to high throttle. It it much more pronouced on a non turbo than a Turbo.

Perhaps the reason it does not for you is that either your driving style does not lend itself to the stumble, or that you are not aware of it happening.

But in every FC I have ever driven with the mod, I can sense the stumble if I push it.

 

Hey Icemark,

I've done a bazillion of these mods and I've never once had that problem on any of the cars that have that done. I'm not sure how else to respond. I have literally done over 50 of these things and sell them all the time and not a single person I've done one for has reported that problem. ???

B

 

Perhaps, again they are not experinced enough to notice this. And remember this is when the engine is cold or cool.

Ask Ted, he'll agree with me on this. Its also posted on his website.

It is the downside to the mod.

 

When I did the full TB mod in my FC, at idle, if I would punch it to WOT, it would stumble a bit before it would begin to rev up. I noticed it immediatly after the TB mod. Didn't bother me though. And I just used my right foot on the break and gas to keep the car from stalling when cold.

 

Correct me if I'm wrong, but isn't stabbing the throttle to WOT from idle a generally bad driving habit anyway? Smooth is better.

Also, how would removing the aux plates on a NA affect behavior at all? They just open up when the car is warm to prevent people from whomping on it cold (as opposed to the fancy little dance they do on the TII).

-=Russ=-

 

They're not experienced enough? The "50 some-odd" figure I replied with earlier also includes me. I've had the "version 1" mod of this done on my TB for 7 years now. And, back then, I never noticed the downside you're talking about, Icemark. Although I am not trying to argue or be disagreeable, the mod that I perform doesn't have this kind of downside to it. Out of all of the people I've done this particular modification for, not a single one has complained about a stumble at throttle. Then again, I do a fairly aggressive job on this: I don't just remove the #4 and #5 plates w/ shaft but I also remove/reduce the four pressure drop points throughout the body, widen the secondary runners out a bit, and scuff and polish the internals to part mirror finish. That might have something to do with it.

Honestly, the only real downside is the loss of 3krpm cold-idle. Even then, the car should idle if everything is fine under the hood-wise until it's warmed up.

B

 

Just out of curiousity. Would I be able to just remove the secondary throttle plates without having to remove the whole damn thing?

 

Worth a try. I don't see how it'd be mega beneficial but it may liven the car up a bit.

B

 

i removed the plates and the rod that held them in thats it and it works fine revs alittle faster.

 

That's a strange thing to say. I would've though that after doing fifty of these you would've realised that the TB has absolutely nothing to do with the 3000rpm start...

I dunno how many times I've explained the "stumble" thing with the TB mod, but I guess I'll have to again. It is only a problem on Turbo engines, because the #2 secondary throttles (the ones that get removed) on Turbo TB are damped to slow the speed they open at. If these are removed, slamming the throttles open at low revs causes a stumble as the AFM catches up with the sudden airflow change. NA's do not have this damping on those throttles, instead they're held open constantly once the engine is warm. The most likely reason for this difference is the much shorter distance from the AFM to the TB compared to the Turbo.

Note that this is also the reason why there's little to no increase in throttle response from doing this to an NA TB. It's the removal of the damped throttles in the Turbo TB that gives the noticible increase in throttle response. The throttles are literally opening faster. This is really the whole point to this mod.

So to recap, to get the "stumble" you need the following:

- A 13BT
- Removed #2 secondary throttles
- Low revs
- A sudden throttle opening

 

Hi Jason, what I mean is the high-RPM start that the thermowax controls. I always associated part of the 3krpm start with this cold-operating function on the throttle body. Whenever I've removed it, there's been a loss of that functionality and thereby a drop in cold idle.

B

 

Nope, the thermowax only increases idle speed to 1000-1200rpm depending on who's messed with the screws. The 3000rpm start controlled electrocnically by the ECU, which opens up both the BAC valve and the AWS solenoid next to it.

 

Do you really have to plug the hole left over from removing the throttle shaft?