TB Coolant bypass.

[CrawlingEye]

I'm now trying a mod that I recently decided to try. It consists of bypassing the coolant lines on your TB.

Consider your TB doesn't produce heat, there's no need for it, and if you've ever felt your intake after driving around town a bit, I garuntee you that you'll find that it's by far warmest by the TB.

I just finally completed it, so it'll be a bit before I can report results (I actually haven't even driven it yet) but it seems like it should be good for some minor gains, and considering the price of it is free (except for a little spilled coolant), I can't see a reason why not to try it.

I'll edit this post later on and post some pictures.

Edit: I forgot to mention the reason the engineers decided to put the coolant line there, and the only potential draw-back... That is start-up, they lengthened the line so that there would be a greater distance between the engine and the radiator. I'd rather have my TB unheated instead of a slightly shorter start-up.

Edited with pictures and guide:

Essentially what you want to do is this...



You can clearly see the (far) coolant line in this picture that I'm disconnecting. You don't need to be removing the whole line, just the part that you see (you can see the hose clamp loosened in the picture), however with this one, it won't make a difference.




Now in this picture, you can see the far coolant line (closest to the inside of the car) on the TB has the clamp loosened again, this is the other line that you'll be disconnecting half of. With this line you do not want to remove both ends, you'll be disconnecting the end that connects to the TB and be plugging it into where the other line in the first picture goes to.

I hope this helps, if anyone needs clarification on anything, feel free to ask.

Again, it took me about an hour to do the whole job, including running to auto-zone for a new hose clamp and adding some coolant.

Edit again:

Here's a finished picture:



You can see where I connected the coolant line removed from the back of the TB to.

[Toysrme]

I'm half way through doing a major port and polish job from the air filter to the heads right now.

I agree on the coolant bypass. I have new lines cut to bypass mine also. I'm also blocking the EGR. There is something else I think alot of people are forgetting about the 3vz-fe engine also. You can block the EGR and make it cleaner, but it's still going to be dirty from the ACIS to the heads. Gotta remember that the 3vz-fe is always blowing fuel into that part of the intake to help with cold starts. I'm thinking of plugging that also so that it doesn't screw up the polishing I'm spending a lot of time doing.

And you might as well put a filter on the PCV valve to keep that crap out of the intake system also LoL!

1) EGR block
2) PCV filtered
3) Coolant by-pass
4) "Start up injector" blocked

FYI the startup injector is nothing more than a fuel line running to a banjo bolt that dumps fuel into the intake.

[Xevuhtess77]

i too am in the middle of port+polish, cept ive got a 1mz. im interested in bypassing the coolant. but what kind of gains would this yield, and why? im not seeing how it would give us any kind of gain

[luisitol]

I don't think this mod is meant to be measured in teh sense of what you gain instead of what negative you get rid of. Basically your TB will run cooler and thus your air charge will be cooler, very minimally, but hey every bit counts. Its an easy/free mod so its worth it.

[CrawlingEye]

Luis is right, like I said before, the intent of them having the coolant run through the TB is to make a larger path between the engine and radiator, so the coolant can heat up quicker during start-ups.

I just had a little bit of a spirited driving session driving home from my girlfriend's house (in nj) and when I came home, I left the car run and popped the hood to feel the TB and top of my intake... to my surprise, it was COLD.

I did notice a tiny bit of a gain in power too. Worth it, IMO.

[CrawlingEye]

Oh yeah, I'll post the pictures soon, I only have some "Before pictures" taken, then my digicam's batteries died. I'll probably run out (if I have time) tomorrow and pickup some more batteries to take the current pictures.

[CrawlingEye]

Updated with pictures.

[Toysrme]

Forget what I said about the start-up injector. Sean says he did it and his car wouldn't start first crank anymore. What would be nice, is if someone would wire up a relay with a pinch on the line so that it would only spray gas when the car was actually starting.

That would be useful. =)

[Camry9294]

I guess this bypass is just for the warm weather? What about when it gets really cold. Tb icing up? or not. Would be nice to wire up a solenoid to open up for those cold mornings.

[88 LE]

Originally posted by Toysrme
What would be nice, is if someone would wire up a relay with a pinch on the line so that it would only spray gas when the car was actually starting.

That would be useful. =)

I'm not sure how the cold start injector on a 3VZ-FE works.

However on my 3S-FE the injector only works when the start injector time switch is closed and the starter is cranking.

The start injector time switch works based on temperature.

FYI the startup injector is nothing more than a fuel line running to a banjo bolt that dumps fuel into the intake.

You sure about that?

On my 3S-FE its a injector. Theres a electrical plug that connects to it.

[Toysrme]

Ah you are correct, I just remembered taking the banjo bolt off of it and forgot about taking the injector out. I guess mine was so black I didn't recognize it LoL!

[dna59]

I have a '93 Cam too and would like to do this mod, but I'm not to clear on what to do. Could you clarify it a lil' more if possible.

[CrawlingEye]

Originally posted by dna59
I have a '93 Cam too and would like to do this mod, but I'm not to clear on what to do. Could you clarify it a lil' more if possible.

You need to find the 2 coolant lines that run through your throttle body.

The easiest way to do this is to disconnect the far coolant line from the TB, and disconnect the closer one (nearer the front of the car) completely. You can then plug the one that's still partially connected to where you just removed the other one from (if that makes sense). You'll notice that there's 3 lines running to the TB. The center one (IIRC) is a fuel line. (someone correct me if I'm wrong)

[Xevuhtess77]

i know the two lines you're talkin about, but im not sure exactly how you're connecting the two lines in order to bypass the tb

[white90dx]

Watch out if you live in a cold climate...

Coolant runs through the throttle body for two reasons:
1. Heat up the air to 'optimal' temperature for better fuel atomization and reduced emissions.
2. Heat up throttle plate and throttle body to reduce the possibility of the throttle plate freezing/getting stuck in the open position.

I suggest adding a ball valve inline for anyone that lives in a cold climate - close it in the summer for bypassed coolant and open it in the winter to keep things safe and running well.

Have fun...

Charlie