How To: 2.4L Throttle Body Coolant Bypass

[olecram39]

I read somewhere about the coolant bypass however i wasnt able to find a detailed DIY for our engines so i decided to make one. Here it goes.

What It does:
From the factory the throttle body has two coolant lines that run through it. One is the inlet and the other one is the return. Honda did this to prevent the throttle body from freezing in cold conditions. In theory, bypassing these lines would lower the temperatures of the throttle body and at the same times lowers the temperatures of the air going into your engine. Colder air = more power.

NOTE: If you live in the colder parts of the world where it gets really cold i recommend you don't do this mod.

What you will need:
7 mm socket
Small Ratchet
Pliers

Here is what your engine should look like without this mod.


These are the two hoses that go into the throttle body.

If You follow these two hoses, the shorter one with the white line will connect to another hose that has a nipple on the side and the solid longer one will connect to the block right next to the fat hose that come from the radiator.



Make sure the engine is cold and take the 7 mm socket with the ratchet and take off the clamp that holds the long solid hose to the throttle body.



Now use the pliers to take off the clamp that holds the short hose with a line to the nipple on the other thick hose. DO NOT remove the hose, coolant will come out if you do, just move the clamp back.

Now grab the end of the solid hose that you had already removed from the and place it close to the striped hose.


What you will do now is remove the striped hose and quickly connect the solid one. The quicker you do this the less coolant you will spill so be prepared.

 
After you perform the last step you will only have the short striped hose connect on one end to the throttle body and the other end disconnected. All you have to do next is connect the unplugged end to the throttle body where the other solid hose was at first.



Then use the pliers to put the clamp back and hold the hose in place.


Then use the 7 mm socket and ratchet to tighten the clamp on the solid hose and hold it in place.

The final product should look like this.


Now when your engine gets hot, the throttle body should be a little colder than it was before. Happy Modding!!

[fatbastard]

on some other cars (Mitsubishis), the motor will forever be on warm-up mode if you do this bypass.

hows the idle RPM at operating temp?

[Jeff Likes Bagels]

I did this bypass on my previous car the same exact way. Except I didn't realize that the one line would start gushing out coolant, so I got caught off guard and lost quite a bit of fluid.

I'm going to have to do this again on my current Accord. Especially now since it's summer and I reach intake temps of up to 120F. As far as the idling goes, I never had any problems when doing this bypass.

[fatbastard]

As far as the idling goes, I never had any problems when doing this bypass.

great!! any improvement in performance?

[Jeff Likes Bagels]

Eh, I'd say a marginal increase in throttle response. I'd say it's worth it since it's a free mod, but don't expect your car to instantly have the torque output of a Cummins diesel.

[CrackerTeg]

Yours didn't have that kind of powa?! You must've done it wrong Jeff.

[fatbastard]

some bloke over at OZHonda.com recorded a 10-15 degree (Celcius) drop in intake temps with this mod. not bad at all.

[Jeff Likes Bagels]

Yours didn't have that kind of powa?! You must've done it wrong Jeff.

I think I forgot the part where you're supposed to hook up a bottle of NOS to the coolant line. I'm not really into energy drinks, but I've heard the power gains are phenomenal.

some bloke over at OZHonda.com recorded a 10-15 degree (Celcius) drop in intake temps with this mod. not bad at all.

Interesting. My OBD2 Bluetooth adapter can read intake air temps and intake manifold pressure. Maybe I'll record some data before and after to get a rough idea of any differences.

[olecram39]

Interesting. My OBD2 Bluetooth adapter can read intake air temps and intake manifold pressure. Maybe I'll record some data before and after to get a rough idea of any differences.

I tried doing this with MY OBD2 adapter but i didnt see any differences. It may have been because the MAF sensor is before the throttle body so any changes in temperature at the throttle body are not measured by the car. A way to do this could be to use a thermometer to physically measure the throttle body temperature after the same amount of driving at the same ambient temperature at the same engine temperature. I didn't have a thermometer to do this but the throttle body did feel cooler to the touch after this mod.   

[CrackerTeg]

I think I forgot the part where you're supposed to hook up a bottle of NOS to the coolant line. I'm not really into energy drinks, but I've heard the power gains are phenomenal.

That's it exactly! Fucking noob.

[Jeff Likes Bagels]

Interesting. My OBD2 Bluetooth adapter can read intake air temps and intake manifold pressure. Maybe I'll record some data before and after to get a rough idea of any differences.

I tried doing this with MY OBD2 adapter but i didnt see any differences. It may have been because the MAF sensor is before the throttle body so any changes in temperature at the throttle body are not measured by the car. A way to do this could be to use a thermometer to physically measure the throttle body temperature after the same amount of driving at the same ambient temperature at the same engine temperature. I didn't have a thermometer to do this but the throttle body did feel cooler to the touch after this mod. 

I see. Fuck it then!

I think I forgot the part where you're supposed to hook up a bottle of NOS to the coolant line. I'm not really into energy drinks, but I've heard the power gains are phenomenal.

That's it exactly! Fucking noob.

Suck it Z! I'll live with my slow car!

... No I won't. Where do I get this NOS again?

[CrackerTeg]

Suck it Z! I'll live with my slow car!

... No I won't. Where do I get this NOS again?

Usually in a convenience store cooler. They're highly sought after so the shelf may be empty when you go.

[Mike]

Could make the same drive on similar temp days. Drop the intake hoes and measure the internal temp of the throttle body with an infrared thermometer

[olecram39]

Could make the same drive on similar temp days. Drop the intake hoes and measure the internal temp of the throttle body with an infrared thermometer

This would be great. However, where do you get an infrared thermometer? Perhaps a member who has one already could do this mod and tell us the difference in temps.

[Mike]

Could make the same drive on similar temp days. Drop the intake hoes and measure the internal temp of the throttle body with an infrared thermometer

This would be great. However, where do you get an infrared thermometer? Perhaps a member who has one already could do this mod and tell us the difference in temps.

There fairly common.