sacred screw and alternate throttle bodies

[Kaladin]

1.  Is the sacred screw only a matter of idle quality, or is there something that I don't anticipate?   My red Norge idles very rough, and the paint is missing from the sacred screw.  Obviously it has been ridden thousands of miles in this condition, and I would normally live with it,  but because I am used to my silk smooth silver Norge it is annoying.  The stepper motor was bypassed 12 years ago.

2.  If I opted to buy some used throttle bodies and stepper motor to try to improve it, will the 8 valve throttle bodies work with the 4 valve engine, or do I have to be specific?  They seem to be easier to find.

Thanks
mark

[Bulldog9]

1.  Is the sacred screw only a matter of idle quality, or is there something that I don't anticipate?   My red Norge idles very rough, and the paint is missing from the sacred screw.  Obviously it has been ridden thousands of miles in this condition, and I would normally live with it,  but because I am used to my silk smooth silver Norge it is annoying.  The stepper motor was bypassed 12 years ago.

2.  If I opted to buy some used throttle bodies and stepper motor to try to improve it, will the 8 valve throttle bodies work with the 4 valve engine, or do I have to be specific?  They seem to be easier to find.

Thanks
mark

Huzo did some experimenting and wrote on this a while back.

It is the factory set of the TB's throttle stop/idle speed, and very difficult to get right once messed with. There are two on the TB, the one on the bellcrank is OK to touch for syncing the TBs (high speed 3Krpm), the other is 'sacred' should not be touched, and is the setscrew that your throttle stop comes up against. Both have paint.

[Kaladin]

I understand, and wouldn't mess with it, but I bought it pre-violated.  I suspect that one of the prior owners was trying to get it to idle correctly with the stepper motor removed.

So since it is already messed with, I am wondering if it is just an idle problem.

[Tom H]

I think Roper did a write up on the Norge TB's. You might do a search for that on your favorite search engine. IIRR it's basically like resetting a V11.

Tom

[guzzi ride]

2.  If I opted to buy some used throttle bodies and stepper motor to try to improve it, will the 8 valve throttle bodies work with the 4 valve engine, or do I have to be specific?  They seem to be easier to find.

The 8V TB's will not work on your 2 valve motor.

[Pescatore]

Does it idle rough at any engine temperature?
Maybe it's not TB related.

[blackcat]

I would start with the easy stuff first, adjust the valves and have you tried balancing the throttle bodies? Do you have Guzzidiag and have you reset the TPS?  I disconnected the stepper motor on my 07 Norge around 08 and never had a problem adjusting the idle.

[Kaladin]

Does it idle rough at any engine temperature?
Maybe it's not TB related.

Yes, at any temperature.

[Kaladin]

I would start with the easy stuff first, adjust the valves and have you tried balancing the throttle bodies? Do you have Guzzidiag and have you reset the TPS?  I disconnected the stepper motor on my 07 Norge around 08 and never had a problem adjusting the idle.

I have reset the TPS and changed the inner spark plugs.   I'll try balancing the throttle bodies today after the game.

[Bison]

Hello folks,
If the sacred screw has been played around with would both the plugs be the same colour?
If you have done all the above you could try the CO2 trim?. My 2007 was snatchy at low revs and the gearbox clattered at idle. I have a Beetle map. My CO2 trim read zero, I adjusted it to +2, the difference is marked, the gearbox clatter has all but gone, and when tested it will pull smoothly from 30mph in 6th,(not that I would recommend it). I'm checking to see what the fuel consumption is like, but the plugs look ok, perhaps slightly rich, if it's using much more fuel I'll adjust it back to +1.
Alan.

[Bulldog9]

I understand, and wouldn't mess with it, but I bought it pre-violated.  I suspect that one of the prior owners was trying to get it to idle correctly with the stepper motor removed.

So since it is already messed with, I am wondering if it is just an idle problem.

Understood. The throttle stop is related to idle speed and orientation of the TPS, the bellcrank and air bleeds balance the TBs at speed and at idle. I was just pointing out that both are painted, and can be confused.

As Blackcat says, Fresh Valve Adjust and TB balance should help. I'm sure I will get shot here, but when you do the High Speed Balance with the bellcrank, the air bleeds should be completely closed, and then when you adjust the balance at idle you should start with them fully closed. You MAY be able to increase base idle speed by opening the bleeds more. The increased air will do what the Stepper Motor does by allowing more air to bypass the throttle plates.

A few other things
- Make sure the vacuum ports and EVAP lines are not leaking.
- Make sure the Stepper motor ports are completely blocked.
- Use GUZZI DIAG to reset all fuel trims and clear learning parameters
- Make sure the motor is up to proper running temps before doing the balance
- Is your stepper truly FUBAR? Missing?

You will get it it straight!

[Kaladin]

Understood. The throttle stop is related to idle speed and orientation of the TPS, the bellcrank and air bleeds balance the TBs at speed and at idle. I was just pointing out that both are painted, and can be confused.

As Blackcat says, Fresh Valve Adjust and TB balance should help. I'm sure I will get shot here, but when you do the High Speed Balance with the bellcrank, the air bleeds should be completely closed, and then when you adjust the balance at idle you should start with them fully closed. You MAY be able to increase base idle speed by opening the bleeds more. The increased air will do what the Stepper Motor does by allowing more air to bypass the throttle plates.

A few other things
- Make sure the vacuum ports and EVAP lines are not leaking.
- Make sure the Stepper motor ports are completely blocked.
- Use GUZZI DIAG to reset all fuel trims and clear learning parameters
- Make sure the motor is up to proper running temps before doing the balance
- Is your stepper truly FUBAR? Missing?

You will get it it straight!

Balanced the throttle bodies on Saturday and I can't believe how much smoother it is running at speed.  Almost as good at the sliver Norge.

The manometer I brought in from work is a differential manometer, measuring only the difference in pressure between the two throttle bodies.  Which was a pain because it didn't average so the reading was jumping all over the place.   

Next step, Beetle.

[Huzo]

I got excellent results with this mercury filled dual tube setup.
https://youtube.com/shorts/um5MnfzZXUg?si=AAYVrZUE2ETnD3Bj
As you can see, it does not pulse at all and great for setting the balance at high/ low speed.

[Kaladin]

I got excellent results with this mercury filled dual tube setup.
https://youtube.com/shorts/um5MnfzZXUg?si=AAYVrZUE2ETnD3Bj
As you can see, it does not pulse at all and great for setting the balance at high/ low speed.

It's been a long time since I saw that much mercury in one place.

[Kiwi_Roy]

I got excellent results with this mercury filled dual tube setup.
https://youtube.com/shorts/um5MnfzZXUg?si=AAYVrZUE2ETnD3Bj
As you can see, it does not pulse at all and great for setting the balance at high/ low speed.

Its pretty hard to figure out what you are doing there.
I think mercury should be banned, I once worked on the site of an old chlorate plant where they lost several tons of the stuff into the ground, they ended up taking train loads of the dirt to a hazardous waste disposal site in Alberta
I built an on-line mercury analyzer for a plant treating the groundwater pumped from multiple wells on the site, kept me busy for a year or more.