Just got my A-spec suspension installed today and also found out about a neat little mod you can do to the throttle body to keep it cooler. Jtso from the TSX forum showed me this mod. I guess the TSX guys have been doing it for a while unbeknownst to the TL forum. The mod consists of rerouting the coolant line that flows through the throttle body. Apparently coolant is run through there to warm the air perhaps for colder climate areas. By removing the inlet and outlet lines and connecting them to each other instead you end up with a much cooler throttle body. Verified this after driving around for about 30 minutes on the freeway. Throttle body was only warm to the touch instead of hot. Just requires a couple of hose clamps and a coupler. No more than $3 in parts. I will post pictures soon. Driving impression were slightly more responsive throttle in the lower rpms. When doing the mod make sure to clamp off both hoses and put a rag underneath to catch any coolant drippings.

 

Is'nt this step two or three is the AEM CAI install instructions? I seem to remember that they even give you a connector fitting and clamps? I will have to check this out! Thanks!

 

yes, but this is a bad idea for people in colder climates. i''m in NY, i'd bypass it real quick at the track or dyno just to see what happens, but wouldn't drive around like that in the winter.

 

How does it effect it? I live in Indiana and have been driving around like that all winter? I havent noticed anything adverse that I know of anyway>just wondering?

 

A matter of fact...I was just thinking about it....I love doing runs the colder it is...car seems to make more power the colder it is? More dense air?

 

uhm, i dont get it.

 

well i have heard that condensation can build on the throttle body and cause freezing, BUT it's not necessarily a very common thing. it's good to hear people doing this in colder climates. i may try it but it's one of the few things that worries me. i'd like to see a few more examples of this before i actually do it.

 

coolant gets hot, the hot coolant flows through your throttle body causing higher IATs

 

ya but where is it? is it on the aem intake? is it right at the connection between the intake and the engine? i k now the op is going to put up pics, but anyone else have an idea. i just dont know about the throttle body portion

 

When you installed your Injen intake....you most likely put this on. It was the coolant line relocate part of the install.....you remember the small white connecting barb that came with and the line you cut.....I think this is what they are talking about.

 

take a look at the actual throttle body unit, the part that the CAI attaches to on your engine. you should see a hose at the bottom. i forget where the exact inlet/outlet is on the new TL.

 

It runs fine in the cold weather. I've bypassed the coolant feeed to both throttle bodies throughout this winter and I haven't had a problem with them freezing or anything... and my car's seen weather as cold as nearly 0 degrees.

 

Couldn't figure out how to post pictures but I found some on this forum that do. If you look at pictures 9. 10. and 11 of this link https://acurazine.com/forums/motorsports-news-7/wrc-some-one-maybe-back-130633/ it shows the coolant line being bypassed by the throttlebody. I connected the two hoses to each other using 90 degree elbows but I will probably just put in a new hose going from inlet to outlet. MichealBenz, you are right about the AEM CAI instructions for doing a coolant bypass. I guess for those of you not planning on a CAI right away you can do this modification initially.

 

^-do those pictures work for you? They are not hosted anymore or my link wont connect me. If you have pics to host go to www.imageshack.us its really easy and all you have to do is copy the link they give you once a pic is uploaded

 

I dont see em either....seen em before....just verifying for you!

 

Ditto. We had a bunch of us TSXers do it in all over the winter climate (me Ohio, a few in Canada, NY, etc). Never had a single issue at all. Lowest temp recorded in Cincinnati, OH was 19F when I left for work in the morning.

The only time you really notice a diff. is after a driving on the highway and you get off to a stop. Then you kick it into traffic... there is a little more HP and torque than I was used to having. For us TSXers, every bit of HP and ft lbs we can get is a good thing.

 

i agree, but my thought process is.. why are the coolant lines there if they appear to serve no purpose but hinder HP/TQ?

 

They are put there for the potential of the throttle body freezing, so all manufacturers are preventing a problem that doesn't normally exist. You sacrifice a few HP/TQ to do that.

 

How much gain can one reasonably expect by doing this? Has anyone dyno'd this beyond a "butt dyno?" It seems to me that, if the gain is worthwhile, the manufacturer would've designed a thermostat into the works such that it only runs the coolant through the TB when it's actually needed.

 

It is less about gains than it is about keeping what you already have.

 

I don't understand. I'm just trying to figure out how much is gained/not lost by doing this change. In other words, if it's actually worthwhile, why didn't the manufacturer set it up with a thermostat?

 

To those who are concern about the functionality of the TB (sticking) under cold weather condition, perhaps a little info on the design of the TB would ease your mind. Below are some pics of a TSX DBW TB which is very similar to the TL. In fact, you can bolt a TL TB to the TSX.

Coolant cover: The cover on the left is where hot coolant goes in and out. It's just a hollow chamber. The cover on the right is another empty chamber. There is a small hole inside probably being used as vent hole for the drive motor.


Drive assembly:


DBW internal:


Drive gear: Note the two spring sets. One if for normal throttle plate return from open position, one is for returning from completely closed postion. The TB does a startup self check and closes the plate completely for a second, then returns back to the normal position. These springs have high tension.


Drive motor:


DBW control module:


TB normal position:


TB plate adjustments: Note the adjustment screws at the top inside 12 o'clock and bottom outside 5 o'clock positions.


Now let's analyze the possibility of the TB freezing without the coolant lines. Freezing point is 32 degrees F. If the car is exposed to freezing temp, the coolant doesn't get warm the second the engine is started. In fact the engine heat under the hood will reach above 32 degrees very quickly. The throttle plate is driven by an electric motor and the return is controlled by the high tension spring. Therefore, throttle sticking is not likely to be an issue.

 

Excellent Post and Great Information! Good point...in drive by wire....whats gonna feeze. Glad you were able to share this with us! You are absolutely right....whats gonna freeze here? Again...thanks for sharing JTSO! Much appreciated!

 

I agree "Excellent Post and Great Information!" Love the pic's!!! I live in Minn. I would like to keep the functionality of the warm water. Has anyone seen a petcock (or valve) I could put here to switch between summer and winter position! Now that would be the BEST of both worlds!! A solenoid (12v) with a switch in the cab would be nice!

 

Thanks for those pictures. Ive never bothered to do any sort of research or inquiry into the TB. Pictures are great

 

Here is an idea to keep the coolant flowing during winter and bypassed during warm weather. However, I don't believe anyone actually had to do this because it's not really necessary to keep the coolant flowing through the TB even in cold weather. If nothing else, it's good for discussion value.

What you will need is a couple of valves, fittings, hoses and clamps.

Before coolant bypass: The typical stock configuration with hot coolant flowing through the TB.


Valve and fittings: You will see how it is placed in the diagram later.


Bypassed flow path: Valves closed


Normal flow path: Valves open

 

The only real purpose is to warm the air before it enters the motor. By warming the air it helps with emissions. I had a STR 70mm TB on my Prelude. It was made without coolent pass in it. In the 3 years I had it, I never once had a problem with it. Given I live in the south, but it still gets cool down here. I personally wouldn't worry about doing the mod any place I lived( north or south). It is not very likely that the throttle body would EVER freeze closed, unless you ran through a monsoon then went straight to freezing temps. If anyone has ever played with nitrous, you will know that it is extremely cold, as is any condensed gas, and when I say gas, I mean periodic table gas, in this case Oxygen. If sprayed on a surface, nitrous will form a icy film. This is also why they use bottle warmers, to excite the molocules in the bottle so it will flow faster. When using a fogger system, you are spraying it right before the TB, this does not freeze the TB open. Any one that has used N2O will understand. The gain on something like this is nominal, but when you are trying to get every little pony out of a NA motor, you do everything you can. If you don't feel comfortable doing something like this, don't. But this is a place for us to discuss options that can be done to the car to help improve performance, and that is what we are doing!! Again, if you think that it would cause a problem, don't do it, but for the rest of us, I am sure it will be something on the mod list for most ofus shortly.

Jason

 

great stuff guys, i'll be bypassing my TB this week.

 

I have wondered if this warm water would help heat the car up faster. Like in sub zero temp's. When you want the heat to flow into the cab ASAP! Also Do you get as good a mix at sub zero? I mean does the fuel atomize as well?

 

You mean something like this.....(conceptually)

 

Ya man!! That would work! (conceptually)......
I wondering now after reading the posts here. That maybe I don't need this? I did have a CAI on my 2k RSX never gave me any trouble. So .........

 

None of those parts are exposed to the incoming air except for the TB plate inside the housing, and that's the only part that has a possibility of freezing and/or sticking. DBW or mechanical, the linkage setup isn't a concern; just the plate.

 

Is it possible that the coolant flow is keeping the mechanisms 'cool' in the summer? It gets 90 degrees + here in Atlanta with 70%+ humidity in the summer.

 

Nope, not possible at all. Once the thermostat is opened, the coolant line have the same temp as the rest of the cooling system, which is approx. 176 F and up to 200+ degrees F.

 

I live in Cali so i dont have to worry about freezing. Does anyone have a step by step guild to reroute the coolant? I cant seem to find an online install guild for the AEM cai.

 

Ditto.

 

Its really easy, on the bottom of you throttle body there is two hoses attached to it that has coolant running through it. Disconnect the two hoses and make them connect to eachother. Either use a new hose, or connect the two ends with a hose extention. Something like what is used in the earlier posts. Just make sure the two hoses are bypassed from the TB.

 

Any specific plugs/connectors you used that match the factory tubing diameter?

 

dont bother buying anything. just remove one hose completly. and connect the one still attached to the motor to the now empty connection from the one removed.

 

Yes, I'm bringing this outta the grave. Maybe it's just me, but I don't remember bypassing the TB when I pu tmy CAI on. I thought it was just a longer hose connecting to the same place?? Somebody remind me.