well i got bored and did the tb mod, it feels great, the engine revs faster and much smoother and idles just fine. it seems to have a little more power and torque across the whole rev range. so i say anyone thinking of doing this should. one question is that when my engine is not under load ie..idling or in neutral while braking the engine light comes on, but once i hit the gas it goes away. has anyone had a similar problem like this? ill pull the error code tomarrow cuz i dont feel like doing it in the dark.

 

Didnt have that problem when I did it. It will help when you pull the code though

 

i'm a newbie and i'm stupid..what is TB mod??

 

Goodness, its when you remove the secondary throttle plates and the cold start assist in the process, supposidly giving you better throttle response.

 

ok....how exactly do u u do that?? please show me the light or maybe a link how to..thank you

 

http://fc3s-pro.com/TECH/HOWTO/TBM/tbm.html

 

can u do this mod on a n\a? or is it just turbo?

also what are the advantages? and whats bad about it?

 

You can do it to an NA as well. Some people love it, others have complained bitterly about the results.

Feedback and comments:
https://www.rx7club.com/forum/showth...light=throttle


Porting the intake manifolds:
https://www.rx7club.com/forum/showth...threadid=79511


edit: another write-up -- http://fc3s-pro.com/TECH/HOWTO/TBM/tbm.html

 

Probably something with the TPS

 

it fucked my **** up UP, luckly I found a UIM and TB with BAC, TPS and all the stuff on the upp intake mani...for 30 bux!!!! gonna try and keep it stock much more low end....

 

The NA TB works differently to the turbo one. The turbo's #2 secondary plates have a delayed action, so removing them improves throttle resonse. The NA ones don't have this delay, so there's much less effect from removing them. There's a small improvement in flow from the lack of restriction.
Note that the removal of the thermowax (cold-start idle-up system) is not required for this to work. It's a seperate system that can be left functioning normally. Removing it will mean the engine will not idle until it warms up.

 

Also, make sure you use the appropriate materials if you do decide to take out the cold start assist. Rico05 I believe used JB Weld and thinks it may have been the downfall to his engine I believe. I think he said he found little peices of jb weld in his engine.

 

That is wrong. The thermowax pushes the TB open a little more allowing more air, and the TPS compensates with extra fuel. Removing it will NOT keep the car from idling until its warm. Ive seen that problem way too many times, and I can tell you its always vacuum leaks that keep the car from idling until its warm. Ive got a ported motor, all emissions removed, TB mod, etc, and my car will hold a solid idle right after you start it.

 

However, removing the cold start thermowax may make the car hard to drive in cold weather until the engine warms up. I say leave the cold start system. My version of the TB mod is simply removal of the secondary throttle butterflies, leaving everything else in place. All the benefits, none of the downfalls.

 

I just started mine up today for the first time cold after doing it. and it won't hold it's idle. I gota hold the pedel down for around 20-30 secs then it'll hold an idle.

water temps were at 55F before starting. I let off at 80F and it held.


my warm idle is set at the stock 750. if I bumbed that up abit, it would probably hold when cold.

 

Like how JBWeld doesnt compress nearly as well as gasoline?

 

Here is where I was asking about that:

https://www.rx7club.com/forum/showth...hreadid=168628

 

I removed the the cold start and fast idle when doing it and my car still jumped up to 3krpms when started....and its pretty stupid to say you have a vaccum leak if you car doesn't hold a solid idle right after you crank it, after it gets warmed up I'm assuming the vac read is fine and in scotts case he has no vacum rac so there arn't that many places to have a vac leak

 

That's right... No it doesn't. The TPS has very little to do with fuel delivery. The extra air is measured by the AFM and fuel is added accordingly. It's no different to opening the throttle using the gas pedal. Mixtures are then enrichened based on info from the coolant thermosensor. I'll clarify then. Removing it will keep the engine from idling properly until its warm. I'm sure that is a common cause of idle problems, particularly when the TB has been removed and reinstalled, but if this system wasn't needed, Mazda wouldn't have put it there! What's your idle set at? Does it hold a smooth 750rpm when warm? Can it do that cold?

 

well it was the tps that needed adjustment, im still fine tuning the idle to get it correct, its not the most fun thing to do concidering i my open exhaust wakes up the neighborhood...o well

 

LOL Your supposed to do the tps adjustment with the car off.

 

My main reason for the TB mod was to remove that small coolant hose from under the UIM. It had failed on my 87. That was the only time I ever towed the rex.

 

*****still jumped up to 3krpms when started****

That's a function of the bac and the Air Bypass Solenoid, not the thermowax.

 

yes i understand this, but i have to start it and make sure everything works right...which 9 times out of 10 doesnt b/c i am still trying to get a normal idle back or atlest below 1000rpms

 

I removed the plates on my '86 N/A, I have had no problems with the car afterward (except the whole not being tagged thing )...it was definately at great mod in my opinion.