R1200RT Stumbling Advice wanted

[windyducat]

I have a 2005 R1200RT with a very annoying low opening throttle problem. When I gradually open the throttle nothing happens initially and then all of a sudden the RPMs jumps. Instead of smooth and progressive, it is jerky. engine Conversely as I roll off the throttle just before it is closed the RPMs drop like a rock. At slow speeds this cause bucking as it is more like a light switch than a smooth increase of power, especially between 1,000 and 3,000 rpms. I like to work on my bikes and prefer to resolve this one myself.

 

The bike has 16k miles and was serviced at 12k miles by a certified shop. I bought the bike with 13k and inherited the problem so not sure what led up to it.

 

My first inclination is it is either TPS or throttle sync. I pulled the plugs and they are burning clean, and not too lean. Below is my plan of attack but would appreciate advice from others here.

 

1. Reset the TPS. Allow the ECU to reset using the standard procedure of disconnecting the battery

2. Balance the throttle bodies

3. Replace the spark plugs

4. Check the Charcoal canister for gas

 

5. If that does not solve the problem, then buy the GS911 diagnostic tool and pull the fault codes and read the stats for potential source of the problem.

 

What am I missing?

 

TIA! Cal

[bobbybob]

I would think this is caused by the idle stepper motors disengaging when opening the throttle, combined with the wrong cable tension causing the rpms to jump suddenly. Mine also does this, but not to the degree the OP states. With mine, the rpms actually decrease slightly when opening the throttle (very slowly) followed by sudden increasing rpms.

 

Anyone who is more knowledgeable, please step in. I'd also like to know. I have a suspicion it involves the steppers.

[windyducat]

Thanks...I'll add the stepper motors to my list of things to check.

 

To be more specific on the symptoms. In neutral, if I very gradually increase the throttle, the RPMs bounces around a lot until they reach 3,000 RPMs. For example, I doubt I could hold a steady 2,000 RPMs in neutral. Even the slightest throttle inputs - at initial throttle opening - cause the RPMs to jump around, lower and higher. Past 3000 and under all other circumstances the engine runs great, and throttle response is spot on perfect.

[dirtrider]

Hi windyducat

 

Your problem could be one or more of many things, ignition, fuel, or fuel computer wise.

 

Obviously the TPS would be near the top of my list. Maybe start with the TPS learn.

 

Next would be one of more of the stick coils acting up. So see if it will run on just the uppers then just the lowers. A bad lower stick coil effects lower RPMs more than high RPMs. Don’t let spark plug color fool you as the plug color just reflects combustion not actual sparking plugs.

 

Next would be the o2 sensors, a bad or lazy o2 sensor can really effect the just off-idle operation.

 

Things like tight valves or restricted exhaust can also cause off idle related runability problems.

 

Won’t hurt to check the TB balance but it would have to be off a long ways to cause what you are seeing.

 

If you can’t find any smoking guns a look see with a GS-911 would probably be in order as that can show real time sensor and engine data.

 

 

 

[Hall Vince]

I would think this is caused by the idle stepper motors disengaging when opening the throttle, combined with the wrong cable tension causing the rpms to jump suddenly. Mine also does this, but not to the degree the OP states. With mine, the rpms actually decrease slightly when opening the throttle (very slowly) followed by sudden increasing rpms.

 

My 57 RT is similar also. I notice it most when the engine is cold. I've actualy had my bike serviced 4 times by a very good dealer and pointed this out to them but they say it is set up correctly. I have to compensate for this on the first few pull aways of a morning or I'll stall it.

 

I borrowed a 2010 GS for two days while mine was in for service. The GS didn't exhibit the same dip just off throttle. When I got my bike back, guess what. Yep stalled the motor pulling away from dealers.

 

I also suggested that the Servo motors controlling tickover speed drop the throttle before the cables take it up. Must be an adjustment to get this correct somewhere but may not be normally checked unless realy bad. (Like the OP)

I recall on a car I had there was an adjustment to be made of a few thou on the stepper controller for correct throttle atuation. Just a screw to loosen and a feeler gauge, job done.

Not sure if the RT can be set like this.

 

I get used to mine. Just a niggle.

\v/

[windyducat]

Hi windyducat

 

Your problem could be one or more of many things, ignition, fuel, or fuel computer wise.

 

Obviously the TPS would be near the top of my list. Maybe start with the TPS learn.

 

Next would be one of more of the stick coils acting up. So see if it will run on just the uppers then just the lowers. A bad lower stick coil effects lower RPMs more than high RPMs. Don’t let spark plug color fool you as the plug color just reflects combustion not actual sparking plugs.

 

Next would be the o2 sensors, a bad or lazy o2 sensor can really effect the just off-idle operation.

 

Things like tight valves or restricted exhaust can also cause off idle related runability problems.

 

Won’t hurt to check the TB balance but it would have to be off a long ways to cause what you are seeing.

 

If you can’t find any smoking guns a look see with a GS-911 would probably be in order as that can show real time sensor and engine data.

 

 

 

Great suggestions.

 

I have started the TPS learn, and will check the coils and replace the plugs as they are due.

 

The bike came with a remus exhaust which I thought was the problem, but was still there when I switched back to the stock exhaust.

 

Question: I assume the best way to eliminate the O2 sensor is to replace them??? I could look it up, but what are the replacement intervals...I assume I am not wasting $$ replacing them at 16,000 miles.

 

 

Thanks again.

[dirtrider]

Hi Vince

 

No adjustment of steppers on the 1200RT, in fact they are electronically controlled and don’t retract on throttle up like the steppers on older cars. They hold the idle setting until throttle up then just sync together.

If it was a stepper related problem it would cause an erratic idle well before any throttle up issues.

 

Not even sure how a person could check them for operation on the 1200RT without a GS-911 or dealer service computer as the pintle is internal to the TBI. In no case “EVER” try to run those steppers when removed from the TBI as the pintle will fall out and they are a REAL Bit*h to get back in properly.

 

[dirtrider]

 

 

Question: I assume the best way to eliminate the O2 sensor is to replace them??? I could look it up, but what are the replacement intervals...I assume I am not wasting $$ replacing them at 16,000 miles.

 

 

Thanks again.

 

Hi again windyducat

 

Very difficult to test the o2 sensors as there is no real on vehicle or off vehicle test that is accurate without using a GS-911 or service computer.

 

I’m not sure what the replacement interval is but way-way above 16,000 miles.

 

The easiest way to do a quick test is to disconnect them then ride the bike, if the problem disappears you have a good chance the o2’s “might” be the issue. If the bike still runs bad with the o2’s disconnected your problem lies elsewhere.

 

Any chance the original owner installed a performance computer chip or other fuel controller on that bike when installing the exhaust?

 

[swilson]

Mine acted similar when a coil started acting up. Lucky for me it was just a bad connection at the connector. After wiggling the connectors on the wiring to the coils the problem went away.

 

[windyducat]

Quick update...

 

The TPS was reset using the basic relearn procedure, WOW, what a difference. Before the engine would not hold consistent RPMs anywhere between 1,000 and 3,000 RPMS - it would "hunt" all over, and changing the slightest throttle input would cause the RPMs to bounce all over. Now between 2,000 and 3,000 the problem is gone ..it runs like tractor; holds the RPMs and the RPMs mimic the slightest throttle changes.

 

Now between 1,000 and 2,000 the same problem is still there, but not as severe. Holding the hand throttle steady at 1,600, RPMs bounce around a bit between 1,200 and 1,800, but not near as bad as before. I suspect I had more than one thing that needs adjustment. My thoughts are do the 18,000 mile tune up and see if problem goes away, and while I am at it check the coils. I also noticed that the idle is a little rough. Idle is pretty steady at 1,100 RPMs, but there is an occasional misfire. It does not purr, more there is a "bump.....bmup, bmup........bump". Is this normal?

 

Any thoughts or similar experiences?

 

Cheers! Windy

[dirtrider]

Now between 1,000 and 2,000 the same problem is still there, but not as severe. Holding the hand throttle steady at 1,600, RPMs bounce around a bit between 1,200 and 1,800, but not near as bad as before.

 

Any thoughts or similar experiences?

 

 

Hi Windy

 

It seems about all the 1200’s I have looked at do that. It's maybe something in the engine control software. Not sure if it is an on-purpose or just a glitch due to the decel fuel shut off the shuts the fuel off on dropped throttle.

You think your bike is bad just go try on the new cam head. There is almost an open slot in the fueling control in that RPM range sitting still. You really don’t feel it while riding the bike.