1 kzte throttle body butterfly.

Joined
Mar 8, 2007
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Bristol,UK
Hi all,
I've been reading a few post from down under and it seams that a few of them remove the butterfly from the throttle body to improve air flow, is it as simple as that or am I missing something.
 

GTSSportCoupe

2LTE abuser
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Worked great on my 2lte! Can't see why it would not be different for the 1kzte. Gave my engine more grunt at the very low rpms. Seems to keep EGT's down too, as there is nothing limiting air to the engine. I feel it's easier on the turbo too, as there is no blow off valve on these engines, a sudden close of the throttle at high boost is not really a good thing. Removing the butterfly will cease EGR operation (no vacuum to suck exhaust gasses into intake), so you should remove the EGR system at the same time.
 
Joined
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Thanks, I've already taken off the egr system, so it's just there to cause vacume to suck in exhaust gasses?

Do take out both butterfly's or just the big one.
 

GTSSportCoupe

2LTE abuser
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Thanks, I've already taken off the egr system, so it's just there to cause vacume to suck in exhaust gasses?

Do take out both butterfly's or just the big one.
The butterfly is there primarily for the emissions systems (EGR), yes. Some folks like to think it is also to limit run-away situations if there is a injection system failure. Also it makes engine shut down a little less harsh (less air being compressed on engine shut down).

I took out both butterflys. Leave the throttle shaft in and the Throttle position sensor untouched though. The ECU will still need that signal to work properly. The throttle position sensor needs to be adjusted very carefully with a feeler gauge if it is removed, so best just to leave it alone.

You'll need to drill out the screws that hold the butterfly in, because they have a permanent lock-tite compound on them and don't screw out.

I removed my whole throttle body to do this job, and used a drill press to drill out the screws.

Again, I'm refering more to the 2lte with my experience. But I think the 1kzte is very similar. It runs basically the same injection pump and EFI system.
 
Joined
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Auckland, New Zealand
 
 
You'll need to drill out the screws that hold the butterfly in, because they have a permanent lock-tite compound on them and don't screw out.
I did my 1KZTE on the truck... Just put a rag down the intake first to catch anything that falls....:)
The screws have the ends that stick out the back peened over like a rivet and wont undo.. File off the tails and they should unscrew ok....
Or in my case I sheared off one and with a pair of pliers unscrewed it all the way thru :mad:
And as said EGR removal / blank off goes hand in hand with this mod.
 
Joined
Mar 8, 2007
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Bristol,UK
I wish someone had said to do that before!:doh:

What a difference, the turbo spins up quicker,less smoke and is bound to be more economical!

I always wondered why the butterfly was there and now understand when I doodle along with a light foot it was struggling to get the air in and would black smoke a bit.

There should be a sticky list on here on what mods to do on each engine for newbies.
 
Joined
Jan 14, 2008
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If the throttle plate was reducing flow into the engine, would we be seeing a vaccum on our boost gauge (assuming its connected post throttle plate).

I will be removing mine right away because I am getting compressor surge with the new intake volume (front mount intercooler) and high amount of boost
 
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I think the little butterfly would be open but yes it's designed to cause a vacume to suck in exhaust gases..
 

GTSSportCoupe

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When I did it on my KZJ71 I found that I lost a lot of engine braking and a lot rougher on shut down
That is strange about the engine braking, because with more air there is more compression, meaning it should be doing better at engine braking.

Maybe it has something to do with the fueling? Have you 'tuned' the engine at all?

Shutdown is a bit rough no doubt about it. But to me it's no big deal for all the advantages I've gained.
 
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Yeah I guess on long overrun periods when the turbo has slowed down you may loose a bit of engine braking but the benefits far out way the cons.

Mines made no difference to engine shut done! But you can hear the turbo a lot more even at tick over.
 
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Idaho
Again thread from the dead. Today I finally got around to removing my butterfly valve on the throttle. My only tidbit to add is to suggest using painter's masking tape inserted between the throttle body and the air intake manifold, face up, to catch all metal bits from the drilling of the screws mentioned above. That, a magnet, and the shop vac kept all crud from getting in the engine.

For those who haven't yet done this modification along with the EGR delete, do not procrastinate. Blue smoke gone. Engine stronger, cooler. MPG improved.
 

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