I had my 2005 Magnum grooved in November, and have had no fuel economy improvements. Per instructions from The Groover, I've reset the computer, checked for utilities leaks, waited a couple of tanks, etc, all to no avail - still no improvements.

Today, following the example of another recent post for 0 increases, I dismantled the throttle body again, this time taking pictures - see attached.

I think I may have been incorrectly Grooved!

My limited understanding of Grooving led me to believe that the groove was placed next to the throttle body butterfly, on the exterior side - air entering from that side through butterfly's into intake (interior). That's how it "built up" the air wave before sending it into the intake.

As you can see from my photos, I've been Grooved on the interior side of the throttle body.

So, if, in fact, I was Grooved on the wrong side, it my throttle body toast? If I just had it regrooved correctly, wouldn't that leave an awfully thin ridge at the butterfly closed position?

Can my TB be repaired, or does it need to be replaced?

Could this explain why I'm getting this annoying whistle?

Thanks for any suggestions, comments, etc.

Harry

Hi Harry,

The groove is on the correct side and looks fairly clean.

In your third picture you show the TB installed and there is a metal tube that looks like it is going to the manifold just behind the TB.

If that is the line from your PCV valve, you need to redirect that line to the intake plenum on the intake side of the TB.

Where the tube connects on the manifold needs to be capped.

Your not getting any MPG improvements because the PCV line is acting as a big leak preventing the manifold from maintaining a vacuum level high enough to get the full effect from the groove.

If you can confirm that it is the PCV line, move the line from the manifold to the plenum side. The increased vacuum should cause the groove to develop a slight whistle.

A simple test would be to cap the tube and the manifold for a short time to confirm.

If you have an OBDII scanner to monitor the fuel trims before and after that will also be an indicator. The lower the numbers or more negative the numbers the better the efficiency.
Give it a shot and let us know what the happens.

Karl Fortner
Tacoma, Wa.

Actaully, the tube in the photo isn't the PCV. It's a copper (metal) tube coming from somewhere blow. The PCV valve is entering the manifold just behind that (closer to firewall).

When the Groove was first done, the PCV valve was capped. I uncapped it 2 weeks ago to see if there was any difference - none. I get the same performance with the PCV valve open or capped. Actaully, fuel economy slightly increased with it uncapped, but that could be the changes in fuel mix with the onset of summer.

I don't have a ODB scanner. As for moving "it" to the "other" side of the plenum, I don't know what that means - is the plenum the TB/butterfly? Do you mean make a hole in the black air tube attached to the TB and move it there?

As for "cap the manifold"? Wouldn't that mean no air entering the engine at all?

I may be able to borrow an ODBII scanner from Checker, but if everything else looks OK, then that would just confirm nothings changed, right?

Hi Harry that tube is egr. dan gadgetman mo.

Hi Harry,

The tube that is still connected, it would be good to know what it is being used for. An opening that big going to the manifold can make all the difference.

I'm wondering if they are not using that as a pre-heater from the exhaust, the foil covering would make me think, YES.

My suggestion was to disconnect that tube from the manifold and plug the opening that it goes to.

It either will or will not make a difference, so a short term test will not hurt anything.

Karl Fortner
Tacoma, Wa.

So, then the question becomes is it safe to plug the EGR (exhaust gas recirculation)? I'm not familiar enough with internal combustion engines to know if this would/could cause a back pressure problem (or, even if that's possible).

And, removing this from the system would mean I would never pass emissions, right?

Personally, I'd be leary of trying to disconnect and plug that, what with the pressures involved with the exhaust. It wouldn't be nice if whatever cap/plug I came up with fired into the engine compartment!

Could I just unplug the sensor it seems to be plugged into? I'll try that first for a quick drive to see if there's any immediate change.