Rx7TyreBurna

iTrader: (1)

So, I was talking to a friend earlier today, and he said that on an N/A, you can remove both of the upper throttle plates on an N/A. He said that he heard it idles really bad when it is cold though.

Is this true? Or maybe he is confused and misread that only the front can be taken?

Just trying to figure out because I plan on modding my TB. I can deal with a small idle problem when it is cold, but if it will jack the idle a ton when it is warm, then no.

Anywho. Thanks for the info guys!

I always find stuff about the TurboII TB mod. Not much about the N/A though.

rotorpower27

The intakes on an NA are beautifully designed, leave it alone, if you want power, play with the exhaust. you will wind up with vacuum leak or something worse

J-Rat

iTrader: (2)

The TB mod on the N/A is the same basic premise as on the TII. It removes the cold start (thermowax), and the double throtte diaghram. It will give you some cold start issues, and will probably induce a low RPM stumble when you roll into the throttle.

arghx

iTrader: (3)

previous owner removed the double throttle I dunno... it just makes the car sputter a little bit at low throttle sometimes. I don't know if it adds much power, but I did put down 172 at the wheels...

whatever you do, keep the damn thermowax. It is so annoying to not have it on... holding the gas down until the car reaches operating temp. imagine backing out of your driveway down hill and using the e-brake so you can keep a foot on the gas pedal

NZConvertible

You can remove both of the upstream secondary throttle plates. When you pull of the intake duct these are the two open plates in the secondary bores. They close when the engine's started cold to stop you romping on a cold engine, and open when it warms up.

This is not true. Those plates have no effect on idle speed or quality at all.

The procedure is the same as for the Turbo TB, but there are no gains or losses from doing it unless the plates weren't fully opening like they should. You're just removing an engine protection feature.

Rx7TyreBurna

iTrader: (1)

Hmm, maybe I will try and free up the diaphram on the first throttle plates. Mine were frozen shut. that was with car warm. Couldn't even move them by hand.

I would like to keep it if it won't improve performance.

Still going to do emissions removal . I don't like all the tubes everywhere. Clean clean.

Thanks!

NCross

iTrader: (18)

keep the emissions. its more trouble than its worth to remove them on an NA. i have my secondaries removed and i could tell a slight difference in the way the car drives. it was a pain to get it to hold idle and im still tuning the idle and TPS. you have to ghetto rig the thermowax cam with a zip tie to keep it from having a 2400 RPM. Other than that, its fine after you get it tuned correctly. my suggestion would be to only remove the plates and not the rod, thermo wax, vac line, or plungers. You should see no affect on idle or drivability by only removing the plates.

just let it idle for a minute or two before taking off.

84stock

iTrader: (5)

Another labor intensive mod that has more risk than gain........jsut like the guys that do a manual secondary mod on the 1st gen carbs, pointless mod!

NZConvertible

Then you've fucked something up. There should not be any change to the way the car drives if it's done properly. Remember these plates are held fully open the whole time the car is warm (i.e. no effect), and simply act as a power limiter (by restricting airflow) when the engine's cold. Like I said, they have nothing to do with idle speed or quality, or general drivability.

Yep, you definitely did it wrong...

The throttle shaft, vac line and damper are redundant with the plates gone. There is no reason to leave them there. The thermowax is a completely seperate system that has nothing at all to do with the double throttle system. IMO it should be left even if the double throttle system is removed, simply because it improves cold idle quality.

RotaMan99

To be very specific, when removing the thermowax the engine will not hold idle while cold. Removing the thermowax is NOT in no way any type of modification. Its a removal of a part that does not need to be removed.

Removing the 2ndary choke plates will not give you cold starting issues

Not at all. A lot of members that have a n/a when removing the thermowax will adjust the 2ndary throttle plates to have the engine hold idle. This is the wrong way of doing it. You are now opening up the TB without any change to the TPS.

The right way would be to adjust the primary plate on with a bolt on the back of the tb to open it up a little more, then you would have to adjust the TPS back down to 1v (s5) or 1 kohm (s4)

HAILERS

To repeat everybody above who know what and how things work: The outer set of plates are spring loaded to the full open position once the water temp of the engine is fully hot.

Even if the double throttle diaphram is busted internally, the thing will spring load the outer plates to full open. Same with loss of vacuum to the double throttle diaphram. Plates go full open.

There is ZERO benefit to removing them.

Also, as an aside, someone above mentioned a *damper*. Sorry, no damper involved on a non turbo car. But you know that and mispoke. That's what you get, being a turbo owner commenting on a non turbo. humor

RotaMan99

Just to add to my self here.

The thermowax holds the primary plate open while the engine is warmed up and this is the main reason why you can make small adjustments with the idle screw instead of large ones since the primary plates is already letting a fair amount of air by. Removing the thermowax will allow the primary plate to completly close which is why you may see threads about owners that did this so called mod and now their engine does not hold idle. Then members will tell them to open up the secondaries. WRONG

If the primary plates needs to be open to hold idle and to allow the ecu to calculate the throttle opening and airflow correctly. Opening up the 2ndaries will cause other little issues.

With that said, when the primary plates closes the TPS reading will actually be very low so when you open up the primary again with the bolt on the back of the TB, which you will probubly have to remove and install a longer bolt, the TPS reading should be the same. You need to look in the FSM to make sure the amount of opening the primary plate is, is correct to allow a proper adjustment of the TPS.

If the throttle opening is incorrect and you adjust the TPS to where its supposed to be at idle warmed up, it will actually still be out of adjustment.

NZConvertible

This was posted as I was typing so I missed it. The procedure is the same but the effect is definitely not because the NA and Turbo TB's work differently. The stumble is only a problem on Turbos because of the much longer distance from the AFM to the throttles. That is why the upstream secondary throttles on Turbos move with the gas pedal but have a damped action. On NA's they're held fully open and play absolutely no part in the engine's operation once it's warm.

Yep, I should've said actuator for the NA. Turbo has a combined damper/actuator.

NCross

iTrader: (18)

i know they open up fully when warm, but the fact is that there is about a half inch mass in the middle of the air passage "blocking" air. Do you not agree that air is being blocked when there is a 1/2 inch rod in the way? I know the most you can get out of it is maybe 1% more air flow but still. it simplifies the engine a bit more.

Just dont be an idiot and floor the car into 1st and red line it as soon as you turn the key. let it sit for a couple minutes while you buckle up and put in a CD and roll the windows/sunroof down.

BTW i said to keep all of the coolent lines and vac lines or it will run like crap. All of the "how to remove secondaries" write ups tell you to remove them.

You have the option of safety wiring/ziptying the thermowax to "open" so it will not have a high idle. if you dont do this the fast idle cam will jam up and it will not idle normally untill the wax rod is fully extended.

riptyde

iTrader: (5)

This is so true. I did the tb mod and removed the thermowax and I like it just because everything is so much cleaner by the throttle body. The only thing i didn't like is that i had to jb weld the hole where the shaft when for the secondary throttle plates. And as far as having to manually warm up the car, let me just say, my car will not hold ilde until it has reached about 3/4 operating temp. After it has reached this point, it runs real solid. I like it it. I will do this mod on every rx-7 I will own. Its all preference, choose yours.

-riptyde

NCross

iTrader: (18)

Thats why i kept all my lines. i can start the car right up and it idles fine./ it used to die when you start it but i just tuned my fast idle/TPS/rear damper/idle screw. Only thing i dont like is that i have to tune the car to run at 1300ish RPM when warm. anything less and the car dies as soon as you start it or rev it before it warms any.

if i had the choice to go back in time i would have left it alone. its a big pain in the *** to do and once you have it tuned decent you dont notice too much difference.

NZConvertible

The throttle shaft is nowhere near 1/2" in diameter. The TB is huge for the power the NA makes, so removing a small restriction from a small restriction makes very little difference to performance. There's no reason why it shouldn't be taken out (as long as you do it right), but unless the throttles were not fully opening before you won't notice any difference.

There's no need to wait, just keep the revs and load down until it's warm just like any other car. It doesn't take that long to load a CD and open the windows either...

The coolant lines are for the thermowax and the vac lines are the double throttle system. Two totally separate systems. If you remove the double throttle system, there is no need to leave the vac lines there. There's only one vac connection on the manifold that needs to be capped when you remove them.

RotaMan99

What plates did you open to help the engine idle. 2ndary or Primary?

That is one thing I don't like about the thermowax, the hotter the engine, the more the piston extends which can lower the idle. You will not have to worry if your cooling system is funtion correctly though.

I left the thermowax on and bent some 5/16" SS solid fuel line from the back of the TB, under the UIM and to the water pump housing where it is connects with rubber line. No messy lines now.


Like NZ says, keep the rpms and the load down while the engine is running cold and you will be fine. I have been a startup and go guy with mine even in 0 degree weather. Rpms stay under 3000 rpm with light throttle and engine is fine.

Another thing people will rant on me about is I run 20-50 year round. Takes the engine about 15 seconds to get above 20*F which is the starting temp range for 20-50. Either way, there is still lubrication.

Why not put the thermowax back on?

Why not just adjust the primary hard idle screw on the back of the TB and be done with it? You will not have to touch anything else.

arghx

iTrader: (3)

Meh, I probably should put thermowax back on but I don't drive my T2 that often and I've always got some other project for it so I can't get motivated to do it.

NCross

iTrader: (18)

1. I do have the thermowax on... i even said so above. it has no effect on the engine whatsoever if you dont have the cams jamming up, and im planning on removing it tomorrow.

2. i always wait a minute or so before taking off unless the car has been driven already. i run 20w50 year round, i let the car run for 1-2 minutes in the winter too. thats not that long. just stop being in such a hurry to go somewhere and let the car run for at least 30 seconds before driving.

3. whats the point of trying to argue how long it takes to get comfortable in your car??

4. it took a half inch rubber "cork" to seal up the secondary throttle shaft. holes.. if my assumptions are correct then this means the secondaries are roughly 1/2 an inch...or do you disagree? 1/2 an inch is slightly larger than a centimeter for those of us who are used to metric measurements. my plates were not completely level when warmed up. you could push them another few millimeters.

i was not planning to gain 20 horsepower, i just wanted to simplify my engine a bit more. like i also stated earlier, i am still tuning the car hoping to get it to hold idle after throttle inputs on a cold start. i removed the plates maybe 2 weeks ago and have been too busy to work on it, but im getting closer. its come a long way from having a 2400 RPM idle. ill have it back to 800 RPM hopefully tomorrow. im going to the store to buy some hosing and vacuum nipples to remove the thermowax and vacuum plunger.

NZConvertible

This isn't quite correct. Once the engine temp reaches a certain point the fast-idle cam separates completely from the linkage, so the thermowax has no further effect on idle speed until the engine has cooled down again. You can see this by operating the thermowax linkage by hand. Better yet take the TB off the car, run boiled water through the thermowax and watch what happens.

RotaMan99

I have had different experience. Although, now that I think of it. I think I saw it out of adjustment last time I looked back there.

NZConvertible

It would have to be way out of adjustment for the roller to not seperate from the cam. Once they seperate, there can be no more effect from the thermowax. If they have seperated and idle speed keeps dropping, you have other issues.

RotaMan99

I wouldn't doubt it. Really

HAILERS

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