Rough Cold Start and Idle

Well, I am stumped. This topic has been discussed before, but I was unable to find any answers. Perhaps someone can shed some light?

My ride is a 1999 R1100RTP (104 k miles) with Remus exhaust, no catalytic converter, and charcoal cannister removed. I also removed the cat code plug to stop after firing when decelerating and starting the engine. I rode most of the 2009 - 2010 Winter without any issues.

Late Fall last year, with the onset of colder temperatures, my bike began to be hard to start. Even when warm, I would have to play the throttle at stop lights to keep from stalling. I sounded a bit like a Harley at a stop light.

Since Christmas and the onset of multiple snow storms I have done the following:

Installed a new fuel filter, new air filter, did an oil change, new O2 sensor (Bosh universal with Posi-Tite connectors), rebuilt the throttle bodies (Bing kit), reset TPS, balanced the throttle bodies with a Twin Max (idle is at ca. 1050), and installed a new battery. Of course, tanked up with fresh fuel.

Now the bike runs great when warm or hot. Getting the bike started, however, is a chore and seems to be even worse than before the tune up. The throttle advance barely helps and I have to hold the throttle wide open to get started having to then keep the idle above 2000 rpm until I have 1 or 2 bars on the RID. Until warmed the motor runs very rough, almost as if it were not balanced, or not getting sufficient fuel.

Has anyone had a similar problem and been able to solve it? Any technical advice is appreciated!

What about the spark plugs??? You didn't say anything about changing them. I used to have a 99 R1100RT, and the bike ran much better after I installed Autolite spark plugs. I believe the number is 3923. Good luck...

It may be going lean. Injector cleaner? Temperature sensor?

kgadley01 said:

What about the spark plugs??? You didn't say anything about changing them. I used to have a 99 R1100RT, and the bike ran much better after I installed Autolite spark plugs. I believe the number is 3923. Good luck...

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I knew I forgot something. Yes I installed new spark plugs and adjusted the valves.

PGlaves said:

It may be going lean. Injector cleaner? Temperature sensor?

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I did clean the injectors last fall, but had not considered the temperature sensor. Do you know what their life expectancy is?

I will see if I can find a replacement and give that a try. Thanks for the tip.

How much alcohol is in your gasoline? Ethanol burns poorly when cold.

kthutchinson said:

How much alcohol is in your gasoline? Ethanol burns poorly when cold.

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I tend to purchase gasoline from Sunoco or BP, and I do not know their Ethanol levels. In our area there are no stations, such as Shell, without Ethanol. Since I did not have this trouble last winter, however, I would not suspect the fuel composition to be the problem.

As a follow-up, I have replaced the temperature sensor with a new one => no change in cold start-up behavior.

Today I removed the fuel injectors and blew carb cleaner through each (via a 5 mL syringe attached to the fuel injector and spray can; activating the injector with wires to a 12V battery). I could not see any difference in the volume or spray pattern of the injectors. After reconnecting everything the bike still started rough, but a little better. Of course it was 60 F instead of 30 F.

Not sure if it makes sense to send the injectors out for refurbishment.

Unless anyone has other suggestions, I may just put the bike back together and live with the issue.

Resolution

After living with the rough starting, including during the warmer weather of spring and summer, I think I've found the solution.

I replaced the spark-plug cables with "newer" cables. I purchased used RTP cables with lower miles (30k instead of 109k). Upon installation of the new cables, the startup problems have gone away.

I'm not sure how to explain this resolution, but am glad nonetheless.