Wierdness.....

[TexasMule]

Son rides a 2006 R12RT w/28K miles. Bike starts perfectly fine and idles (cold), runs fine at speed until you pull in the clutch and then it dies. It may run fine when cold because the "fast idle" is still on. I assume when the bike warms up, the bike loses its ability to idle.

 

I ride a R1150RT so I'm not as familiar with "stepper motors",

"electronic choke", etc. everything's mechanical on my bike.

 

We thought it might be some bad gas, but if that was the case, the bike should/would run like crap, even at speed.

 

Any thoughts?

[dirtrider]

Afternoon TexasMule

 

A few things could be causing your stalling problem.

 

Top of list would be a stepper motor getting lost. That is the usual cause of OK cold idle but stalling at dropped throttle clutch-pulled-in after riding for a ways. (this is very difficult to diagnose at home without a new stepper motor, or better yet two, to install as a test).

 

Another other possibility is one or both 02 sensors getting lazy or defective. (again rather difficult to diagnose at home without a GS-911 or thorough knowledge of the 02 system & how a voltmeter sees it).

 

There are other less common possibilities like engine sensors, or throttle cable issues, but without a GS 911 or good electronic fueling system knowledge those will be very difficult to find or isolate.

 

My money is on a failing stepper motor but that is just a guess from afar & even then no idea what side.

 

[TexasMule]

Afternoon TexasMule

 

A few things could be causing your stalling problem.

 

Top of list would be a stepper motor getting lost. That is the usual cause of OK cold idle but stalling at dropped throttle clutch-pulled-in after riding for a ways. (this is very difficult to diagnose at home without a new stepper motor, or better yet two, to install as a test).

 

Pulled a GS-911 on the bike and the only fault thrown was an "air sensor defective". This may have been caused by the use of a "booster plug" which by-passes the original air flow sensor. I can't see where a bad air flow sensor would cause the lack of an idle. More likely to either run lean or rich.

 

Idle control devices (#2) aren't to be trifled with lightly. $152.38

 

 

I think I'll disconnect the booster plug this weekend and see if it still throws an air flow sensor fault.

 

If it doesn't, and it doesn't correct the problem, then I'll look at the stepper motors. Yuck.

[hopz]

 

I think I'll disconnect the booster plug this weekend and see if it still throws an air flow sensor fault.

 

I am no technical wizard but I think the "booster plug" disconnect is a great start.

 

IMO, the stock bike will only have problems with the alterations from stock such as the booster plug.

[racer7]

Can't say I agree- I expect the cause to be elsewhere rather than the Booster Plug itself. Its merely a temp spoofer that enriches fuel mixture by about 6% in open loop mode. AFRs even without a booster plug vary from 12ish to almost 16 and center around 14.7 at cruise (closed loop controlled by oxygen sensor). A small variation isn't going to cause significant problems though it can be enough to smooth behavior during acceleration. I run on some BMWs an AF-XiED that can alter AFRs in closed loop by much more than 6% and have routinely run race motors that use AFRs in the 11s during accel, using the extra fuel to help keep EGTs in control. Small variations can impact behavior and power but the motor won't quit over small changes.

 

Its install could be an issue but if its put in properly not a likely cause. A bad temp sensor by itself won't cause the described problem either.

 

Its possible something got scrambled installing it- look at cable ends for example.

 

Be careful about steppers- if you take one apart you will learn that it doesn't go together easily. They do go bad but not often.

[dirtrider]

Afternoon TexasMule

 

A few things could be causing your stalling problem.

 

Top of list would be a stepper motor getting lost. That is the usual cause of OK cold idle but stalling at dropped throttle clutch-pulled-in after riding for a ways. (this is very difficult to diagnose at home without a new stepper motor, or better yet two, to install as a test).

 

Pulled a GS-911 on the bike and the only fault thrown was an "air sensor defective". This may have been caused by the use of a "booster plug" which by-passes the original air flow sensor. I can't see where a bad air flow sensor would cause the lack of an idle. More likely to either run lean or rich.

 

Idle control devices (#2) aren't to be trifled with lightly. $152.38

 

 

I think I'll disconnect the booster plug this weekend and see if it still throws an air flow sensor fault.

 

If it doesn't, and it doesn't correct the problem, then I'll look at the stepper motors. Yuck.

 

 

Afternoon TexasMule

 

Your BMW 1200RT is an Alpha N fueling system & those don't use an air FLOW sensor. (Strictly throttle angle vs RPMs)

 

The Booster plug effects the Intake Air Temperature not the intake air flow.

 

Was the air sensor fault you saw on the GS-911 a current or a stored (past)?

 

If not current then probably from a past disconnect.

 

If you decide to play with your stepper motors DO NOT (EVER) key up with a stepper plugged into the wire pig tail but removed from the Throttle Body.

 

The stepper pintle will quickly screw itself out & it is REAL PAIN to get them to go back together.

 

[WestyLancs]

I had similar issues with 2006 RT

 

Cut out thread

 

and

 

Second thread

 

In a nutshell, started fine, and ran ok, usually for 150 or more miles, then on pulling in the clutch to slow, or stop, bike would cut out.

Started first prod of the button, even without cycling ignition off and on, and ran fine from then on.

The links above explains what I did, including adding a 'spoofer' to the air temp sensor, which had no effect, apart from lower the indicated intake temp (using GS-911).

 

Finally sorted it by replacing both stepper motors (decided it was easier, and possibly cheaper, than trying to work out which one, if not both, was faulty)

 

Have had no problems since.