TOPIC: question on doing the double groove on a 94 Honda Civic

I was about to attempt the second groove on the opposite side where we put the main groove when I noticed that there are two air holes of some sort right in the center of where I would put the secondary small groove.

Does anybody out there know what those two air holes are for and how should I proceed?

God Bless,

Joseph

Joseph that big hole is the entry for Idle Air Control. Put up more pics give some good ones of the underside. Often we reduce the airflow in the IAC circuit, within limits. IAC lets a controlled amount of air to bypass throttle plate to both allow for an idle and control idle RPM's. A variable valve in the IAC air path is computer controlled to regulate idle speed. Sometimes the IAC valve is never closed fully--air bypasses the throttle, giving in effect a controlled vacuum leak.
There are posts in Index area top left corner tys page to give you info on different TB's that have had that done.

What bit were you going to use for your second Groove?

Tracy G

My bad- spoke to soon here! Definitely need to see more pics of this one Joseph. IAC passages I've seen usually have one opening above and another below the throttle plate. Took me a few more looks at pics to see the 2 big holes. I would guess that big added housing on the right side could be for an IAC valve, but I need more view of this TB to figure it out. Some mfg's TB's are simple, others more involved, depending on how many things are integrated in a given TB. What do those 2 holes connect to?

Tracy G

Not the large holes.

The two very small holes. One is right on top of the other.

I'm going to use the small bit.

God Bless,

Joseph

As far as the two large holes, would it be a good idea to fill them in with JB quick and then drill smaller holes for the air by pass?

God Bless,

Joseph

Joseph, I would not spend alot of time on doing the second groove as on most it will not show any gains and on some it will take away some mpg. Just groove it normal and you should see some gains.

But I have done the main groove and to make a LONG story sort: I didn't do it right the first time; it's right now; I cleared the ECU a dozen times before I got it right and lost my initial gains in RPM's; never really got mpg gains.

This is the same 94 Honda Civic EX VTEC.

Were those Honda cars that didn't like the small bit second groove?

God Bless,

Joseph

Hi Joseph, I went back and re-read your first post thread on this Honda, incl. what I said back then. Did you ever get it sorted out? Did you talk w/ 4 Wheel Bill? Is idle RPM OK now? Was there air in cooling system? In those pics the Groove looks real wide and wallowed-out to me. I didn't realize that Honda used a 2 stage IAC system, not surprised though.

Don't try a second Groove unless it's OK in all respects- and prob. not at all without the Certified Reverse bit. Perhaps on another TB that's correct for this car... as an Experiment

You have tried to faithfully use most of the Gadgetman techniques on this Honda. But as "busy" as this one is, I would hesitate to "kick open any more doors" unless I knew there weren't any more "bad guys" left behind the ones already kicked open.

So if there are remaining issues, we can try to solve them together. Once again- how is it running now?

Tracy G

The idle was fixed for 95 percent of the time. It was fixed by bleeding the radiator fluid and by tightening up the idle screw on the throttle body.
Bill recommended that I widen the air reroute to improve on the cold start(I did that this morning 3/8/14). Here in Wisconsin it has a hard time starting in the cold weather. I normally have to attach a battery jumper to get going in the cold morning.
So is there another special little bit for the second groove or can I use the normal little bit for the second groove?

God Bless,

Joseph

Joseph, the second above throttle plate Groove was "discovered" by Sergei a Gadgetman in Russia who had the Certified level bit set like I do. There are special bits in that set, some are what Ron called reverse bits. Reverse bits like it implies cut a Groove in the reverse shape of normal. You could try to do it with a regular small bit, but I can't advise it. It would be real "Interesting" experience IMHO. If you use a small reg. bit held against the throttle plate from above, the Groove would be backwards, remember it is a directional design. I'd concentrate on ironing out what you have right now first. IF ya want to mess around w/ another TB that's the same correct one for your ride, you could, but I wouldnt try on the only TB you have for a daily driver.

The hard starting in the Wisconsin cold- is it that it's just plain hard to get to start, or that it won't hold a fast idle when cold? I'm going to guess that the fast idle IAC is controlled by coolant temps. Climate is a consideration when doing the IAC mods- Ron was in Phoenix for most of his mods, never had to sweat cold weather, hot-- oh Yeah! In many /most cases the ECU uses the IAC to increase idle RPM when A/C is engaged. IAC flow path can be restricted to enhance man. vac., but the climate and usage need considered when figuring how much restriction. IAC is an analogy to both the old carb. fast idle cam, AND the A/C throttle positioner solonoids from the carb. days.

Did enlarging the IAC restriction help?

Tracy G

I have yet to put the throttle body back on to see if there's any improvement on the cold start because I was strongly considering to do the second groove if the small bit has the same head as the certified special bit and the only difference being that the certified bit is longer in length to reach and do the second groove. So is it?? This Honda throttle body is small enough for the small bit to reach.

God Bless,

Joseph

Joseph- NO the Certified Reverse bits are not the same as reg. any size...I'd put it back together see whatcha got...

Tracy G