Idle issue killing me

[Rocket Scientist]

I found early on I had to turn in the "never adjust" screw. I believe that sets your base idle speed. The engine relies on that until the idle stepper finds the happy spot (target idle speed). Ever since I adjusted the stop screw, I have to set my TPS numbers higher as well. There is some linkage between the throttle butterfly shaft, and the stop screw, that wears. I tried a new TPS at one time. It didn't help. I'm back to running the original old style TPS with 75,000 miles on it. I carry the new one I bought as a spare.

 

[Anomaly]

@Rocket Scientist do you mean the throttle stop adjustment screw?

 

[Rocket Scientist]

@Rocket Scientist do you mean the throttle stop adjustment screw?

Yes !

 

[Anomaly]

Yes !

Yea, I messed that up as well the first time I tried to set my TPS/ISCV. I was able to set it back to where it was, and put a dab of super glue on it. You may try backing it all the way out to where the adjustment screw barely touches the stop.

 

[Rocket Scientist]

Yea, I messed that up as well the first time I tried to set my TPS/ISCV. I was able to set it back to where it was, and put a dab of super glue on it. You may try backing it all the way out to where the adjustment screw barely touches the stop.

I adjusted my stop screw intentionally. What mine would do for example, coming off a highway ramp and stopping, it would idle at about 4 or 5 hundred RPM's, and rough like it wasn't getting enough air. If you watch in TuneECU, when you open the throttle, the stepper thinks the idle is too high and retracts. If the base idle is too slow (stop screw), the engine struggles until the stepper extends out again to open the butterflies. That takes time because it is on a control loop, and moves in small increments. Mine has been fine since I adjusted the stop screw (about 8 years ago). I now set my TPS to 0.66v. Every once in a great while, it will do the high idle / slow to return to idle. When it does, I hook up TuneECU and reset the adaptives and it's good for another six months.

 

[Joesmoe]

Wow, my bike now is doing exactly the same thing (high [1,800 RPM] idle, followed by momentary drop, and back to high idle).

This happened as a result of something that happened during my removing and disconnecting things during the cam replacement work.

I'm thinking I would like to restore confidence in the fundamentals (how to check effectively for air leaks ?), before following the steps described here with stop screw and such.

 

[1K9]

The worst kind.... Brrritish Electrical Gremlins!

 

[Joesmoe]

I just ran the vacuum leak check with the propane method, and could find no variation.

O2 sensor is checked 'off' in the ECU map.

'high' idle around 1,750, then drop momentarily to ~1,000 and back up, stay up for ~5 seconds, and drop and go back up.

 

[Rocket Scientist]

How does your cruise control open the throttle ?

 

[Joesmoe]

It's a bit ingenious. There is a spool that takes both the 'open' throttle cable from the hand grip, and an 'open' cable from a vacuum servo, and there is an 'output' cable that is routed to the throttle quadrant.

Been on there for several years, and all worked fine before this job.