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!!