TOPIC: 2000 Mazda B2500 - First Groove

Hi Karl First off that's about the best Looking Groove I've ever seen!

Does the bit fit Groove tight w/ little/no wobble? Dit you check work w/ flashlight inside/out for leaks?

Ditto for what everbody else has said here. Vac. leaks are magnified by Groove and are worst enemy of results. After all we are increasing/magnifying manifold. vac. during intake stroke.

This is textbook example of how a Groove can look perfect yet not deliver results, IMHO.

But don't want to do many passes w/ bit to get such a nice look! How is the idle quality, smooth or rough. How old is Oxygen sensor? Condition of Ignition?

There has to be a fly in the ointment somewhere (vac. leak). How did it run pre-Groove, how does she run now? Did you follow instructions to re-set computer (batt. cables)

Do keep at it, cause if the bit fits that Groove tightly, you have a talent here!

Tracy G

Hi again Karl, just read rest of this thread. It's late goin' to bed right after I write here.

Ok- leave the PCV valve in place, trace it's hose to manifold vac. source. Remove PCV hose at manifold vac., plug/cap that vac. source. Re-route the PCv hose into the breather hose, tee into breather hose or connect into air intake duct before throttle body. If you cap vac. port, be aware most parts store vac. caps will crack/leak in months (silicone caps avail. on Ebay)

From what I see the idle air port dumps pretty far off to side away from Groove, so in itself might not hurt waveform too much. But I'd examine TB to see if you might restrict flow thru this port.

Go to WAR search/kill vac. leaks they are likely reason for no improvement, PCV is BIG offender here!

Once you do these, I'd be Very surprised if no improvements!

Let us know how it goes, this one ought to do well!

Tracy G

After your detailed explanation, first with Carlos and now with me, I think I understand about the hose reroute.
Thanks again for your detailed explanation. Will give it an attempt.

Hey Karl, you're Welcome! The more I explain stuff the better I get at that too...

If you get a chance to It would be great to see more pics of this Groove from other angles. And feedback about how bit fits it(see latest training Manual).

As per the PCv hose re-route pic you posted--That's one where I would wonder about oil/water gunk being aspirated back into that Throttle body (TB). The nipple for that hose is right next to throttle blade. I guess this another car in pic, but principle applies.

I wont get detailed here, I put up extensive data 'bout that and a way to deal w/ oil aspiration, If it's an issue. Just check, pull the hose off nipple and look inside now and then after the re-route. You can search for Air-Oil Separator on this forum to see more.

Ron cut the trail "thru the Mountains" for us all. I try to smooth out some of the bumps on it if I can.

doin' great Ken, Keep goin'!

Tracy G

Since that port is so well under in intake manifold and hard to get to I think I just may cut the hose from it where its in the open(or just where I can touch it since the rest is unaccessable) and plug the hose with a bolt like I saw Ron do in one of the videos. From there I can somehow take whats left of the hose from the PVC and connect another hose to it to bring it up to the breather hose and then cut breather and tee it off.
Should work that way I guess. Will also attempt to plug some of the hole from the idle air in the TB.
Will take pics if all is accomplished without problems.

Did the PVC reroute to the idle air with a T and capped the hose from the manifold with a bolt in the hose like I saw Ron do in one of his videos.
Also blew some carb cleaner in the IAC piece after removing from the TB while I had the TB off.
Then closed some of the hole from the idle air that goes into TB past the groove just to make sure it didnt interfere with the grooves purpose. I think I see just a little more HP but not what I hear from others. So I guess there still is some vacuum leak or maybe the EGR is doing something to it. Hate to just change the EGR if its working since it costs over $50.
Here are some pics of the IA hole reshape.







I used an old empty caulk container as a base to shape the JB Kwik to the same shape as the TB. Also had to wedge some paper on the opposite side between the tube and TB so the tube laid more flush to the side I was going to mold. Note that if anyone attempts to do the same thing I did, you have to smear a light film of oil(I used vaseline) on the caulk container where the JB will touch the tube so the JB Kwik does not stick to it when you pull it out. You could also just use a business card like Ron does between the JB Kwik and the container also but then you have to deal with the paper sticking after. Make sure also you clean the spot(I used acetone) where you will be placing the JB Kwik or it wont adhere right. Am going into detail on what I did because I appreciate when you and Ron go into details. The little things that seem so simple can be overlooked and cause much frustration.
The first pic is after cleaning TB at idle air, then how I set the tube in place, then what the finished mold looked like. This did cut off much of the hole so it shouldnt interfere with the groove now.
Just wish all the work(didnt get to bed until 3am) was all it needed but one thing I did forget to do and that was to pull off the positive cable and ground it. Was in a hurry since it was late(and my third time removing the TB) so would that have any effect on not seeing any HP increase? Also didnt do all the stop and starting procedures for resetting the computer in the training manual to reset the ECU. My press for time,since it was 3am and had to get up for work in the morning, made me quit and call it a day. Still in the learning process and the manual is very thorough but forgetting things I learned when tired.

OK, Karl, did you route PCV hose into the Breather hose or into a hose that connects to Idle Air Control? Make sure PCV hose is tee'd into breather and NOT IAC hose. Bolt in manifold vac. hose should work fine.

It could just be your terminology that's throwing me here, but be sure!

Gotta give credit again, you got that IAC port in TB new-clean! And using a caulk tube was a nice fit in the throttle bore.

Having said that--I would not do it like this! AS I understand the IAC mod...

Objective is to reduce airflow thru the IAC port, AND re-direct that airflow as needed/possible.

The epoxy dam you built will shield the Groove waveform from the IAC airflow. But this dam has relatively little support/contact with the aluminum TB casting. I'm a bit nervous about it possibly losing some material into the intake manifold.

And this dam isn't restricting airflow thru the IAC, just walling it off some. IT's risks outweigh it's benefits IMHO.

The actual IAC port itself, I would remove that dam and instead see about filling in that port. Or you could leave the dam and back-fill behind it down into the IAC port. I'd find a way to make a removeable flat piece to extend down into that port. To leave an opening to left side of the port.
A piece of plastic maybe a coffee can lid or thin aluminum flashing. Could use thin cardboard stock like a matchbook cover etc. to cut to fit into port. When satisfied w/ shape/fit of cardboard then cut plastic or metal flashing to match the cardboard.

Use a small drill bit as Ron says to rough up the aluminum casting before filling in the port, need a slightly rough surface for JB quick or other to bind to, it's gotta stay fast.

How does air get to this outlet IAC port. IS IAC valve integral w/ TB? Some cars like many Fords you just make a restrictor thin plate to go under IAC valve using new gasket(s) then sandwich the restrictor plate under the IAC valve. Just a small hole in restrictor plate, like 1/8" diameter can suffice, IF the IAC valve lends itself to this. Got to remove IAC valve to see if this would work. Easy to re-do this thin plate, to change hole size if needed.

Restrictor plate for IAC is much easier than epoxy filling when you can use it. Beer can aluminum could work! And it's pretty easy to remove/change restrictor hole size and re-install a restrictor plate, IF it can be used.

If you want to Karl, more detailed pics of the IAC setup on this TB would help heaps! If IAC is removeable and ya post pics of the valve and inside the ports, I could give better advice. What to do depends on if pintle valve on IAC extends into air passage in TB, or if pintle is INSIDE of IAC valve, see?

Lastly--IAC supplies more idle air to increase idle speed during cold weather or w/ A/C operation. Like a choke/fast idle, or a/c idle control solonoid from old carburetors--IAC does same function. It's there to increase idle speed for cold operation or additional engine load. But w/ Groove we want to force as much air thru Groove past Throttle Plate as possible. It's a proportional thing here re: total airflow into engine.

Once again sorry for long reply, I'm trying to help you AND others who read this. Some Groove jobs are REAL educational!

Stay with it, Karl!

Tracy G

A piece of plastic maybe a coffee can lid or thin aluminum flashing. Could use thin cardboard stock like a matchbook cover etc. to cut to fit into port. When satisfied w/ shape/fit of cardboard then cut plastic or metal flashing to match the cardboard.

If I am understanding you here then could I also just fill in the whole IA port hole (instead of just what I did) and then just drill a 1/8 hole in the fill for the IA? That could serve to keep the groove wave clean and to stymie pressure from escaping down the IA hole if that is what we are trying to do.

Use a small drill bit as Ron says to rough up the aluminum casting before filling in the port, need a slightly rough surface for JB quick or other to bind to, it's gotta stay fast.

How does air get to this outlet IAC port. IS IAC valve integral w/ TB? Some cars like many Fords you just make a restrictor thin plate to go under IAC valve using new gasket(s) then sandwich the restrictor plate under the IAC valve. Just a small hole in restrictor plate, like 1/8" diameter can suffice, IF the IAC valve lends itself to this. Got to remove IAC valve to see if this would work. Easy to re-do this thin plate, to change hole size if needed.

The IAC bolts on to the TB and has a gasket. I did remove but dont know what you are referring to as restrictor plate. I have seen videos where they cut out a soda can and use that as a gasket. Do you mean for me to cut that can and make a new gasket but make the holes in the gasket smaller than the one that is on there now?

Restrictor plate for IAC is much easier than epoxy filling when you can use it. Beer can aluminum could work! And it's pretty easy to remove/change restrictor hole size and re-install a restrictor plate, IF it can be used.


I believe the pin stays in the IAC and does not touch the TB at all. I tried to clean it but its housed in the IAC housing and mounts sideways on to the TB if I remember correctly.
Just found this video with my IAC that I have so you can see. I hope I am allowed to post a Youtube video here.

The pic of the IAC I have is at the 2:10 mark.



Lastly--IAC supplies more idle air to increase idle speed during cold weather or w/ A/C operation. Like a choke/fast idle, or a/c idle control solonoid from old carburetors--IAC does same function. It's there to increase idle speed for cold operation or additional engine load. But w/ Groove we want to force as much air thru Groove past Throttle Plate as possible. It's a proportional thing here re: total airflow into engine.




That is why I am confused about the IA hole and how making new gasket out of aluminum can with smaller hole and replacing where the old gasket is would help.
Also the other hole above groove that leads to an L with nipple into a hose to who knows where could also effect the pressure we are trying to create.
So much to consider and I do appreciate your time in explaining.

Hi Karl!

Well if your engine is same as in that video, then it's easy street far as the IAC goes!
Again if your MAzda has a Ford engine same as in this video then just make the restrictor plate to go under the IAC valve. I think Ron may have a video in Groovy Service bulletins on Youtube.

But this depends if yours is Ford or Mazda engine, which is it? I'll wait for your answer to go further! If it's a Mazda more pics of throttle body will be very helpful, like show the IAC valve and as much as U can of TB from top inside and other angles so I know what you have.

I take it that's not you/your truck in vid. you posted.

Tracy G

Mine is a Mazda but I thought both the Mazda and Ford Ranger were the same. I know I see Ford parts on the engine and the Hanes manual I bought is for Ford Ranger/Mazda b2200-4000 engines so I guess they are the same.
The TB has the IAC connected with those two holes bolted to the side with a gasket between.
Would have to take off the TB again to get pics. Been spending hours on the service bulletins but didnt see the Youtube video on the restrictor plate yet. So I would guess just making my own gasket with smaller holes in not what you suggest.
Also been doing research on the 02 sensors and since they are 13 years old, its time to change.
But would that be the reason why I am not getting any instant HP noticed?
Also noticed with my Scan Gauge that it seems like the MPG is less after grooving and now have a code for my PVC after redirecting. Not too worried with PVC code.
Am anxious to get the results with HP and MPG that I keep reading about but something is not right and am reading much to see if I can find it. Ron even said someone got over 100mpg with the same engine I have in this post.

Thanks again for your input.

Karl--well if your Mazda has an IAC identical to the one in the video, then just get aluminum thin flashing and cut to outline of where IAC bolts onto TB. I think Ron and othere have mentioned 1/8" dia. holes as a good size to put in this restrictor plate. Obvious what's going on w/ this mod.

Therefore I would not bother w/ epoxy in IAC passages in TB, not needed.I would clean inside of IAC w/ mild carb clean, brakecleen etc. get gunk/carbon out before install of restrictor. Easy to change size of holes to experiment. The epoxy now in TB- your call what to do w/ it. Also don't worry about any vac. ports in TB, but do hunt for vac. leaks in anything connected to intake man.

But sounds like something basic still wrong.

Gotta keep looking, Karl! You will learn along the way!

Tracy G

Looking at this picture, I can't make out which hose is teed into the breather hose.

As to your IAC restrictor, it is much easier to use aluminum, reducing the size of one of the openings (doesn't matter which) to 1/8". While you have the IAC off, you would be well-served to clean it. Maximum range on the piston when doing this is recommended. If the flow is too low, simply make that hole a fraction larger and reinstall.

One more thing. Showing pictures of someone else's engine doesn't really help with diagnostics, amigo! We need to see what has been modified before we can give you any real answers.

Ron