Won't Idle When Cold

[bmurphypdx]

07 R1200ST 23K miles. Battery new a couple of months ago. When I attempted to start the bike in the morning (temp just below 40F) the bike would not run unless I kept the throttle open. In other words, it would not idle but would just die. To restart, I had to keep the throttle partially open while hitting the start button. I had to keep the throttle partially open for about the first 5-10 minutes. Then the bike ran normally and started fine later in the day. Today at 50F outside temp, no problem. I've got a couple of months left on warranty so I'll take it in if I need to but that is a pain especially if the problem is not reproducible. Any ideas what might have caused this?

[Jim VonBaden]

You may have a dodgy temperature sensor.

 

Jim

[bmurphypdx]

Thanks, Jim. From your response, I assume there is an engine temperature sensor that is different from the outside air temp sensor (which drives the temperature display). I'm trying to get a better understanding of how this works so I can talk intelligently to the dealer about it. I'd appreciate any further info you may have.

[Dave_C]

this is the sensor that gives you the oil temp. reading on the oil temp. guage. The bike should idle high until warmed up a bit.

[bmurphypdx]

Thanks

[T__]

07 R1200ST 23K miles. Battery new a couple of months ago. When I attempted to start the bike in the morning (temp just below 40F) the bike would not run unless I kept the throttle open. In other words, it would not idle but would just die. To restart, I had to keep the throttle partially open while hitting the start button. I had to keep the throttle partially open for about the first 5-10 minutes. Then the bike ran normally and started fine later in the day. Today at 50F outside temp, no problem. I've got a couple of months left on warranty so I'll take it in if I need to but that is a pain especially if the problem is not reproducible. Any ideas what might have caused this?

 

Bill, there are a few things that can/could cause your cold start/cold idle problem..

 

 

An improper TPS re-set would be one..

 

Fouled secondary spark plugs or bad lower stick coil (or coils)..

 

Obviously either an air temp sensor or engine temperature sensor could be the issue..

 

Some other problem with the fueling system,, fueling computer,, or ignition system..

 

 

--First thing,, did you do a TPS re-set after replacing the battery? If not start there.. Disconnect the battery for about 30 seconds,, then re-connect it,, then turn the ign switch on (do not start the engine),, then fully open & close the throttle twice.. That should re-set the TPS correctly.. (See if this in itself helps the cold starting,, I have seen a couple where it improved the cold start cold idle)

 

--If the TPS reset doesn’t help then you probably should check out the lower spark plugs & coil’s.. The plug part is easy but checking the coils for function is more difficult (probably the easiest way is to disconnect the upper coil wiring leads from the coil’s then seeing if the engine will run on just the lower plugs)..

 

--On the sensors check out—That CAN be done with an ohmmeter but the easiest & quickest is to have the dealer check them out dynamically on their equipment or find someone with a GS-911 & read them out yourself..

 

--On the OTHER problems with the fueling or sparking system about all a person can do work their way though the systems & check the function out..

 

 

Twisty

 

[Mister Tee]

I have a similar problem, but it's a little different.

 

The bike will start up and idle perfectly in cold weather for the first 20 seconds. Then the idle will start get very rough, like something is adjusting something and it will sometimes even die. When it the motor is warm, it idles perfectly, and it idles fine in warm weather when cold.

[CoarsegoldKid]

--On the sensors check out—That CAN be done with an ohmmeter but the easiest & quickest is to have the dealer check them out dynamically on their equipment or find someone with a GS-911 & read them out yourself..

 

 

Twisty

 

Twisty, the sensors I assume you are speaking of are the lambda air sensors. A GS-911 will display a graph but there is no information on what a good, bad, or ugly graph should look like. Can you tell us how to interpret the graphs.

thanks

[T__]

Joe, no not the lambda (02) sensor.. The lambda sensor doesn’t even come on line for a while after a cold start as those things take a while to heat up even on the heated lambda sensors.. I was referring to the IAT sensor (intake air temp sensor) & the engine temp sensor (oil temp sensor),, both are required for proper cold starting fuel enrichment..

 

It’s difficult to tell about lambda sensor operation with out a scope.. The first & foremost thing you need to look for is cross counts (the lambda voltage toggling across the .5v center),, if it is toggling above & below .5 volts that tells you the lambda is at least working & the fueling computer IS responding to it’s output.. Then there is the frequency that the lambda voltage changes to see if the lambda is working properly or is lazy.. (it’s fairly easy to tell IF the lambda is working properly,, way more difficult to tell anything if it isn’t working or toggling across the .5 volt threshold)

 

If the lambda voltage is constant (not changing) then it could be a cold lambda sensor,, or the lambda is defective,, or the fueling computer just isn’t responding to it, or some other part of the system is acting up..

 

Twisty

 

[bmurphypdx]

Twisty1 - I did not do a TPS reset when I changed out the battery. Sounds promising. Thanks.

[Jim VonBaden]

Twisty1 - I did not do a TPS reset when I changed out the battery. Sounds promising. Thanks.

 

I would be very surpised if that has anything to do with it. Having removed the battery on many R1200 bikes dozens of times, I have never experienced this.

 

Jim

[T__]

Jim, I have seen 2 different R1200RT’s act very similar after a battery disconnect.. Can’t say for sure it was a TPS reset but they both cleaned up their cold idle problems right after the TPS re-set..

 

Something easy enough to try just to eliminate it..

 

 

Twisty

 

 

 

[bmurphypdx]

FWIW, we've had three sub 40F days (similar to the day of the original problem) and I have not been able to reproduce the fault. Did not do a TPS reset yet so maybe it was just a ghost one morning.

[pdes]

 

 

Fouled secondary spark plugs or bad lower stick coil (or coils)..

 

 

Out of interest, why focus on the secondary plugs? Aren't all plugs subject to the same amount of use (and fouling)?

[T__]

 

Out of interest, why focus on the secondary plugs? Aren't all plugs subject to the same amount of use (and fouling)?

 

pdes, not on the BMW boxer engines.. The upper plugs operate in a fairly benign environment up in the middle of the combustion chamber while the lowers are at the very bottom of the combustion chamber-- so oil residue,, un-burnt fuel,, about anything that is heavier than air can end up down there..

 

On the twin spark BMW boxers if you foul a spark plug it is usually the lowers..

 

 

Twisty

 

[pdes]

Cheers Twisty. Wasn't thinking laterally!!