TOPIC: VW Throttle grooving

Has anyone Grooved a throttle body like this one. The body is shaped to resemble the arch of the throttle plate as it opens. I thought I had seen a thread in this forum where someone had Grooved a similar TB. I can add more picks if needed.

Hi Prescott! If you can get the bit angle of 22.5-30 degrees up from throttle bore I'd just Groove it. I have not done one of those. Is it cabled or drive by wire? More pics w/be great. If the throttle bore wall looks thin anywhere Groove will be just build up on outside wall w/ JBQuick or equiv. before U cut Groove.

Post more pics so we can see, someone else here might have done one!

Good to hear from you, Prescott!

TracyG Gadgetman reno

Hi Prescott,

The newer Chevrolet products have this design as well, particularly the 07 Avalanche and the 08 Cobalt that I have worked on.

If it is fly by wire, ie: computer controlled, check your idle angle with a scanner and give it an extra degree or two to avoid an unstable idle.

Take your time applying the groove to maintain an even line on the arc.

There is a lot of data here on the forum, if you haven't read through the entries yet it would be to your advantage to do so... it will more than likely generate more questions.

Nick Reitter had commented on another thread about using a cylinder bit to remove some material before grooving but I haven't seen a clarification on that thread as of yet.

Karl Fortner
Tacoma, Washington

Hi Prescott,

I have modified one of these throttle bodies. In order to get adequate bit depth in your Groove you will need to use a cylindrical cutter to take down the ridge to a level where it does not prematurely hold up the bit.

This is also true with a number of GM throttle bodies.

Hi Nick,

The "Ridge", would I be correct in thinking that you are referring to the edge of the arc at the base of the TB?

As noted in this pic'.




Karl Fortner
Tacoma, Washington

Note: Found that if Internet Explorer is NOT in "compatability mode" it will not post pictures.

Here is the aftermath, for an update anyway. This throttle body is a hibrid, flyby wire/cable. It will be installed in a test vehicle within the next two weeks.

Hi Prescott, can you post a pic or describe how this Tb is "Hybrid"? I'm confused as to cabled/computer controlled on same TB? Does the computer operate the throttle blade, and a cable operates something else, like a transmission kick-down...? Just wondering here never saw that yet, Thanks!

TracyG Gadgetman Reno

WOW! I had a lot of times when I didn't froove VW or AUdi just because of that ridge. Seems like almost all of them have ridges inside. Can you tell after checking how much the mileage increased. And did your car need any computer TB adapting after or it made it itself?

As I was told by the supplier, maybe he built it, the flyby wire controls the idle and the cable the rest. There is no IAC circuit on this TB. Nice.
I like the TB design with the curved flow because to me it seems that air will be forced into the groove along a wider band of throttle movement.

Thought id throw a bit of info i found out about VW throttle bodies, i discovered this while looking into replacing a TB on an Audi. Theres a bit of software and a cable called VAG-COM (volkswagan audi group - communication) that goes on a laptop and is needed if you change a TB, or alter the plate position. You need to carry out a throttle plate position reset. In some cases you can leave the ignition switched on for a few minutes until you hear the servo twitch and this might do the trick. The software wasnt that expensive about £20 for the cable and software if i remember right.
Just something i found while researching, havnt had to do one myself yet but thought id throw it out there just incase anyone gets stuck with a VW or an Audi.

Karl,
you have done a few TB that are similar to this. How far away from the throttle plate was your groove?

Hi Prescott,

Looking at the picture a little more it looks like the throttle plate area is designed more like a ball valve that opens up to a flaired venturi.

Regardless, if the throttle plate position is managed by the ecu, I would determine that position, add one degree of clearance to avoid idle oscillation and cut it there.

ie: if the plate idle position is 17 degrees, I would cut at 18 degrees. That usually comes out to being the thickness of the throttle plate.

One of the guys mentioned that putting the groove at the plate position where the engine is cold works well for him.

Karl Fortner
Tacoma, Washington