TOPIC: 1999 Honda CRV- How do I reroute the air flow?

This is a TB from a 99 Honda CRV.
In this picture, referenced to a clock face, the groove will be cut from 3:30 to 8:30. There is a large opening right where the groove needs to go at 7:00. This needs to be filled in, but where do I reroute it? There isn't much material to the left and above the opening.

I can cut a trench for it, but it would be reduced air flow.
Any suggestions?



Thanks!!

Dan Grieve
South-Central Missouri

Another angle:

Hi Dan,

If there is enough meat in that space at the 7-9 position

What you can't do in width you can do in depth.

An equivalent pathway of 1/8" would be the easiest





That would be my first choice at attempting anyway.

For that matter, that little pocket to the left doesn't look like it is doing anything






Karl Fortner
Tacoma, Wa.

Great work, Dan!

If you look at the TB base, you'll see the metal is very thick everywhere. This lends itself well to "trenching" for an optional air pathway. From these pics, I would opt to recut the path of travel heading (from bottom) CCW. Then, upwards using those chambers to save cutting time.

Simply use a round deburring tool to cut your channel. I recommend using 1/8"-1/4" diameter. There are many 350's running around on a 1/8" channel, and some 4-Cyls that needed almost 3/8".

Start by replacing the Idle Air Control valve. I ALWAYS recommend a new valve if the engine has more than 50K miles. They stick and my cleaning attempts have been fruitless. Then, you have a new valve that will have full (and FAST) learning capacity.

Start with the equivalent of 1/8" and see if the ECU and the IAC valve can correct. This is fairly quick following the ECU Clearing Process. Yet another reason to clear the ECU by draining the keep alive memory circuit.

No matter what, when you get done with this one, you are going to know you did something special!

Ron

Ron, thanks for the info. The chambers counter-clockwise from the gap are used for other air flow paths. I think I should go to the left. And Karl is right - what he calls the little pocket is an unused cavity.

Can I bring the new path into the smaller line that comes in at 9:00? I am not sure what that one is for. Or should I bring in the new path just before that at 8:45, or as close as I can get to it?

New Idle Air Control valves are running between $175 and $250. Is that the part, or is there something else you were talking about?

Thanks!

Dan Grieve

Hi Dan,

Here are my two cents...If the chamber to the right is an air pathway to the intake already, then run your idle air "trench" to it. You will have to check if that is so. If it is, you will have a better result because no air will be dumping near the groove. Make the trench the size Ron said and if the idle is a little low, adjust the throttle plate idle control screw to the best idle at cold.

Don't forget the three main steps when doing a mod:

1. Groove it (the throttle body).
2. Cap it (the PCV connection on the intake).
3 Clear it. (drain the ECU memory).

If any of these three is missed you will have little or no results.

You may want to not do anything with the idle air and first do a basic mod. If you do, let us know the results modified without the idle air changed and then after the idle air is changed. You can take a chance the valve is all right and just see what happens without getting a new one it should be fine as your reducing its job anyway. Try it and see, search and research, it's what makes us gadgetmen.

What are your baseline MPG's?

Great pics and Great Work!

Thanks Nick.

The MPG's - I don't know yet. It is a friend's car. I pulled the TB last week and wasn't sure what to do yet, so I took a bunch of pictures and then put it back together.

Once I have the info about what to do with the big gap then I'll get all the numbers from him.

Good idea about joining the air flow to the chamber to the right. I will have to inspect the piece again. You can see in this picture how the air flow goes through the IAC.



The other side of the chamber goes into the TB in front of the plate.



I think I may be creating a loop where no idol air gets into the TB. I'll need to trace it again when I have the piece off. If it doesn't work, I'll have my JB Weld Steel Stick standing by.

Thanks again!!

Hey Dan,
Check it out but I think that if you trench over to the first cavity then trench up to the other port bypassing the plate you will be able to get the extra air in that way. The air will be let in by the valve, be blocked from going into the Groove go back where it just came from and be added to the upper channel which is a straight bypass. I have a bit of experience with the Hondas and they like to bypass a whole lot of air.

Hi Dan,


Would I be correct in thinking that you have two passages bypassing the throttle plate?

One feeding directly to the 1 O'clock position, possibly a fixed idle flow

and the second one going to the 5 O'clock position feeding your IAC, probably used more for cold starts than idling.

At least that is what I think I am seeing now that I have seen the top side of the TB.

Karl Fortner
Tacoma, Wa.

What is happening here is an example of why I encourage everyone to start their own YouTube channel, and to record their modifications like this for all of us to learn by.

Go to the following link. It will take you to all videos on the GroovyServiBulletins with "IAC" in the title. There may be others relevant, but this is a good start.

If you haven't SUBSCRIBED to the channel, do it NOW. You will find watching all the videos there extremely beneficial, even if you don't have a relevant engine. You will learn the PRINCIPLES, the FOUNDATION upon which you will much more capable in the future, when and if we can no longer support one another, if we are unable to communicate.

Now, the link: GroovyServiBulletins - YouTube

I just grooved the TB. I choose the path to the right. Lots of material to work with. I try to make it clean.


Another angle.


I reset the computer. We did a test drive. He notice that the RPM's are about the same, but the engine is not straining like it used to. I took some before temperature readings but forgot to get the after. I will see him again, so I'll be able to measure the difference.

He has 2 days of appointments so he will be driving a lot. I'll have more data/info to share then and I'll post the groove with the correct heading.

Dan Grieve
Missouri

Hi Dan, these are awesome pics of rerouting idle air path, and it looks like a nice clean cut.

Do you feel like a pioneer yet? I love seeing someone break ground on a new idea of Gadgetizing something to make it better.

Hope you are having fun.

Looking forward to the results on your mod. Keep up the good work.

Gadgetmannebraska Aron Cheek