civic_driver

Tools: 10mm and 12mm sockets, flat-head screw driver, pliers, etc.

These instructions are specific for the D15B7. Shouldn't be much different for all D and B series though. Check out the diagrams and you'll figure it out.

I didn't take pictures but I've included a diagram which shows the hose connections. Basically, you don't want the coolant lines that run from the motor to go through the FITV or IACV which heats up the air and reduces power.

Instructions:

1. First, unplug the TPS and IACV sensors.
2. Remove throttle body--there are four 12mm nuts holding it.
3. Remove IACV located on back of the IM--two 12mm bolts holding it in.
4. Reconfigure the coolant connections as follows:



Basically, connection 2 goes to 6 and 6 goes to 4 as you can see in the before and after pictures. No need to cap the holes on the FITV.

5. Remove FITV from throttle body (three 10mm bolts) and place a gasket that is a whole sheet. I used cardboard/paper gasket from a box of cigarettes. Cut the back side of the box and make holes for the bolts.
6. Put the FITV back on the TB (throttle body) with the gasket in between as is shown on the most right in the diagram.
7. Put everything back together (IACV and throttle body).
8. Finally, set a proper idle from the adjusting screw on the throttle body.

Notes:

If you live in the far North this mod might cause problems with the throttle body, FITV and IACV freezing up. You can always do the mod and then undo it if you observe any problems.

Coolant by-pass along with a Hondata gasket or similar (doesn't pass as much heat to the IM) should give you a noticable gain in power in the lower/midrange.

I wrote this in a hurry... hope it makes sense... I'm starving!

Good luck!


EDIT: Put a new diagram along with updated instructions. This is my current setup and is running smooth.


Modified by civic_driver at 10:38 PM 11/5/2005

civic_driver

Btw, I didn't try this but if point 6 can reach point 4 there's no need for that plug in the middle and 3-4 hose is useless. I'll check it out tomorrow and see if the hose is long enough to reach. The simpler the better.

Tippyman

A few questions. i hope you don't mind.

FITV and IACV - wtf are they? (acronyms own me)
Whats the point?
What kind of "caps" and "plugs" are you talking about and what did you use? is the "plug" in the motor line stopping flow or is it a flow thru plug?

Redline96LX

Everyone please note this is a HOW-TO on the bypass, and this is NOT a suggestion to do it. Everyones situations are different, do your research first to find if you should do this or not. Like I wanted a tad more power and I live in atlanta, so in the summer, I'm alright doing it, but for safety and peace of mind, for winter i run it through.

JDMlyfestyle

I will back this gentleman up. Ive done it to my car and 5 local cars.. i live in Indiana. average winter temps of 20 degree's Snow sleet ice all the time and not a damn problem from any of them

and this does get rid of the irratic idle

boostedcivicsir

FITV and IACV - wtf are they? (acronyms own me)

FITV - Fast Idle Thermo-Valve ( if i remember correctly )

IACV - Idle Air Control Valve

turboxsi

yeah but its gotta suck on cold morning starts, because the iacv needs coolant to function correctly and know how much air to bypass the t/b with in direct proportion to the coolant temp. the increase in power is so little, for the lack of a well running engine on cold mornings. iBut i guess to each their own!!


Oh and for the dude that said it stopped his irratic idle, im sure you are just masking a bigger problem to why your engine doesn't idle right.

turboman

Yeah I did this to my car along with exhaust wrap and hondata gasket. Stays very cool under the hood now. I have never heard of anyone having a problem after doing this and not all cars have these coolant lines running to these points.

I'll see how the car runs at 20 below before I say it's a great idea. But honeslty everyone is always wanting to cool down the air into the motor and this is a great way and it's free.

I know for a fact my brothers vw has no coolant lines to either tb or im.

also when starting up in the dead of winter your coolant is ice cold so don't see how that can help.

JeffBro

dang I should do this! Its never gets below 40 F down here in cali.

Oh hey you could rig up some plastic valves if you did want to be able to let coolant flow back through in cold winters you know.

- just an idea

FalkenSiR

fizeks

wow great writeup civic-driver.. i will definately do this over the weekend

civic_driver

Thanks for the sweet comments guys!

To answer a few questions:

Tippyman98:
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
FITV and IACV - wtf are they? (acronyms own me)
</TD></TR></TABLE>
Already answered.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
Whats the point?
</TD></TR></TABLE>
Keep TB/IM temperatures cooler=denser air=more air=more fuel=more power. Also, eliminates any idling issues due to the IACV observing the same coolant temperature all the time so it shows the same signal. This might change with temperature but it shouldn't be as dynamic as it was meant to be. End result=smooth idle.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
What kind of "caps" and "plugs" are you talking about and what did you use?
</TD></TR></TABLE>
Go to PepBoys and AutoZone and ask them for line/vacuum caps and they will point you to them. Usually black, similar to tire caps but without the threads and a little longer. Great for capping off those end plugs.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
is the "plug" in the motor line stopping flow or is it a flow thru plug?
</TD></TR></TABLE>
Flow-thru. You don't want to stop coolant flow inside the motor. My fault, didn't choose the proper wording. Check out http://tinyurl.com/87lv6. It's the INSERTxINSERT that you want. I'm not sure the exact size but bigger is better than smaller.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
yeah but its gotta suck on cold morning starts, because the iacv needs coolant to function correctly and know how much air to bypass the t/b with in direct proportion to the coolant temp. the increase in power is so little, for the lack of a well running engine on cold mornings. iBut i guess to each their own!!
</TD></TR></TABLE>
Shouldn't be a problem in the southern states. In fact it's strongly suggested you do this mod if you live in the southern states. I'm not to be held responsible for any expletive ups you do but it does work if done properly.

The only difference that you will see is that your motor won't hold high RPMs until it warms up so in effect it will take a little longer to warm up than if you had the stock set up.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
Oh and for the dude that said it stopped his irratic idle, im sure you are just masking a bigger problem to why your engine doesn't idle right.
</TD></TR></TABLE>
Yeah, such as a broken FITV/IACV. What better way to get rid of them both than bypass them and gain power/smooth idle at the same time? If you don't like it, you can always get it back to the way it was. Don't let me tell you what to do.

By the way, if you don't have the Hondata gasket, the throttle body and IM will still get pretty hot so you shouldn't have problems in cold weather. Now if you replace the original IM gasket, then you might face problems in colder climates such as in Canada.

The main reason to keep stock is if you want your car to warm up faster (probably 1-2 minutes difference). Other than that, the stock system hinders performance after the car has warmed up.

Hope this helps.. let me know if you got more questions


Modified by civic_driver at 9:48 PM 11/3/2005

peacexisxfree

good stuff for people like me in ca. definitely will be doing this as an experiment this weekend.

JDMlyfestyle

The guy did the right thing.. Im not sure.. did you do this once u seen what i did in my Intake manifold write up?

civic_driver

your intake write up definitely got me off my *** to do the coolant bypass... i've done it to my previous cars though so i knew what i was doing.. just kept putting it off till now

civic_driver

Btw, you can throw away the hose with connections 3-4 and connect 6 to 4 without using an insert.

Tippyman

awesome.

civic_driver

This way the idle will change with the current temperature. If you want a clean install, block the FITV and IACV ports so that air doesn't go in the throttle body. You can get a gasket kit from autozone and simply cut it out the size of FITV and IACV and put the gasket between FITV and TB and between IACV and IM. That should keep the idle stable even with hot temperatures. I'm yet to try this but it should work. I'll let you know how it works practice once I try it.

T-RO

interesting. I live in Florida so i think ill give it a shot since im not too worried about cool temperatures.

dohcdelsol93

nice write up. Since I went turbo when it's cold outside (anything below 70) and my car reaches normal running temps it surges at idle with no load on engine (lights, etc). I'm going to try this just for kicks to see if it cures my problem.

civic_driver

Make sure you don't have any air in the coolant. Also, if you bypass the FITV valve it should fix your problem. If it doesn't, put a gasket in between the FITV and TB along with bypassing it.

O16581724 5 2 5

How does the IACV know when the coolant is warm when it's being looped like that? What's the point of even looping it like that, won't it be the same as it being unhooked entirely?

hapexamendios 2.0

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by O16581724 5 2 5 &raquo;</TD></TR><TR><TD CLASS="quote">How does the IACV know when the coolant is warm when it's being looped like that? What's the point of even looping it like that, won't it be the same as it being unhooked entirely?</TD></TR></TABLE>unhooked entirely would be bad though.. and make a mess

O16581724 5 2 5

Isn't it's only source of coolant from those lines circulating coolant through it? If they're looped, there's no coolant going through it, right?

civic_driver

Well, the IACV is controlled by the computer. THe FITV is the one being controlled by the coolant temperature. At least that's my understanding. THe IACV still depends on coolant temperature but it's controlled by the ECU which gets the coolant temperature from the coolant temperature sensor.

The reason coolant is going to the IACV is to keep it warm so that it doesn't freeze. Coolant doesn't control the IACV directly. It does control the FITV though since that plunger you see is thermodynamic and opens and closes with coolant temperatures which allows more/less air to get into the throttle body.

The way I have mine setup right now is I don't allow the FITV to influence anything. I put a gasket in there to keep those lines locked. You can completely remove it and place a gasket and metal plate on top and just screw it in but I'll be doing that in the future. Don't feel like doing anything pro here just a ghetto setup till I get my swap. Plus, it's good to experiment since you learn more.