setting 2006 620 Idle speed

[Mark_W]

I'm working on my neice's 2006 620. Bing throttle bodies. The idle speed is very low, about 850, and the bike stalls easily. There is little response to changes in the idle air bypass screw adjustment. Smoothest idle is with both scews about 3/4 turn open. Speed changes very minimally either side of 3/4. Fully closed and the engine will stop in 30 seconds to a minute. Fully out and the idle is rough but the engine does not quit.

Valves are OK, compression is good, smells rich. I think that it should start more easily, but this is my first Ducati.
I went through the TB set and sync procedure. Backed everything out, then set the left TB for a TPS reading of 150 mv. Synchronised the throttles using a TwinMax meter. Set the idle screw on the right TB for a TPS reading of 2.7 degrees. The idle is still at 850, so the mechanical stuff was probably properly set before.

We can use the 'choke' control to hold the idle at 1100 and everything is fine. It just occurred to me that I should have checked the TPS reading at this setting. When I turn the bypass screws I can hear air flowing, but the engine speed is not affected.

I must be missing something.

[Howie]

Might be somebody screwed around with the left side side screw.  Also, CO trim might not be correct.  Later I will do some homework and get back to you. 

[Mark_W]

None of the screws had any paint left, so I started at the beginning and slackened off every adjustment. With the left TB llightly closed I set the TPS ad 150 mv. Which I understand to be the baseline. Then, with the bypass screws fully closed I sync'd the throttle bodies. Next I adjusted the idle speed screw on the right TB, at the cable pulley, to hold the throttle at 2.7 degrees (as indicated using JPDiag software). Last, I got to the bypass screws, where the result has not matched expectation.

I've not read anything about setting fuel trim with this ECU.

[Howie]

From the factory manual, steps using the Ducati diagnostic tool left out:

The instrument reads the voltage
output from the sensor.
With the MASTER throttle completely
closed, the reference value is 150
mV±15.
In case a different value is read,
loosen the 2 screws (23) retaining the
throttle position sensor, keep the
MASTER throttle closed and turn the
throttle position sensor until you
obtain the required reading.
Tighten the throttle position sensor
screws (23) making sure that the
correct reading is retained.
Disconnect the adapter (19) from the
TPS and reconnect the vehicle wiring
harness.

Turn the throttle adjuster (20) until
reading a value of: 2.7°.
If you disconnected the throttle
control cable previously, now
reconnect the cable end to the cam
pulley and adjust the cable travel as
indicated in the paragraph “Adjusting
the throttle and choke cables”


CO trim requires a scan tool and exhaust analyzer.  Someone else will have to suggest a scan tool option. Or you could go to a shop that has the equipment.  Factory spec is 1.5%  For smooth surge free performance and easy cold starts, 4-6%.  Hope this helps.

[Mark_W]

The steps for the Bing throttle bodies differ slightly since the TPS is on the left TB but the idle speed and throttle cable are on the right. Overall, the result is the same. 150 mv from the TPS with zero throttle opening, the 2.7 degrees for the idle position.

I am going to have to investigate wether or not the idle bypass passages are clear. I can blow compressed air through them but maybe the side behind the butterfly is blocked or restricted and what I'm hearing is blowback above the throttle blade.

I also have a local shop with an exhaust gas analyzer. I will need to make an appointment with them. Unless I can find the O2 sensor rig that I build for tuning early fuel injected BMWs.

[Mark_W]

Am I correct in my understanding the the "choke" control does nothing that open the "closed throttle" postiion? No switches that I'm not seeing that tell the ECU to use a cold start map?

[Howie]

Yes.

[Mark_W]

Thank you. Much appreciated.

[DarkMonster620]

Just in case, https://drive.google.com/file/d/0ByWmgp1DWQaiZEx5V3JiemJfVHM/view?usp=drive_link&resourcekey=0-YgSCbIrA2mt_WFQlAlpBoA