Triumph Rat Motorcycle Forums banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Bike of the Month Challenge!

1 - 10 of 10 Posts

·
Registered
Joined
·
57 Posts
Discussion Starter · #1 ·
Yesterday I just got my 2003 955i back from its 24,000 mile service. Prior to taking it in I would have an issue with my idle upon arriving to a stop sign and backing off the throttle only when it was very cold out and the bike had not fully warmed up. But as of late, I never had an issue with it until I picked up from getting serviced. I got a call from the mechanic and he said after he did the service he took it around the block and every time he came to a stop or would rev it to no more than 6,000 rpm and let go it would not be able to hold at idle. I took it home and it did the same thing. I would come to a stop pull in the clutch and the needle would fall below 1000rpm and try to recover to 1500rpm for idle and would fail to do so and stall. Oddly enough whenever I start the bike and idles and runs fine. It just fails to hold idle after the rpms are up. Is this an engine failure or possibly something else.
 

·
Registered
Joined
·
7 Posts
Definately not an engine problem. This sounds like idle air control problems, or possibly fuel injection. I'll have to check my service manual, but I'm guessing there is no idle bypass, so you may have carbon deposits around the throttle blade(s). The engine control knows how "shut" the valves are at idle, but when deposits close off the tiny allowance the closed blades supply, it nearly chokes the engine of air. This is a low-cost suggestion: Get some carb cleaner and open the throttle blades. Clean the blades and the lip of the throttle body. This is the simplest and most cost-effective first solution. I only hope this will resolve your issue.
 

·
Registered
Joined
·
57 Posts
Discussion Starter · #3 ·
Drive955,

To access the throttle blades/body do I just take of the tank and remove the air filter which will expose the three flaps and roll the throttle handle to expose the flaps and the seat to which the throttle flaps reside on?? I haven't done this before so I just want to make sure this is what your talking about. I have a manual for the bike and I assume this is the measure to be taken based on what you are describing.


Thanks
 

·
Premium Member
Joined
·
3,434 Posts
JMHbb26, There's a few possibilities to look at.

-When the tank and airbox is off carefully check the condition of the hoses from the throttle bodies to the IAC manifold.
-Throttle body balance. Have this done following the cleaning of the inside of the throttle bodies and their blades.
-The IAC valve may be carbon fouled which would limit or slow full travel.

Do you have secondary air injection?

Brad
 

·
Registered
Joined
·
7 Posts
Sounds like you're pretty much ready to try this. If you haven't taken the air box out before, be careful and take your time. It's easy to miss a fastener and get frustrated. You'll wind up ripping it out and breaking something! When you roll the throttle, you can place something a little on the soft side between the blade and the body. That way you can work with both hands. Just don't drop it in there! Make sure you get the area where the blades rest especially clean. The kind of miles you've accumulated will leave dirt deposits around this area, witch restricts airflow when the blades are shut.
If this doesn't resolve the issue, it may be time to use a fuel injector cleaner. When you back out the throttle, the injectors shut off to increase fuel mileage. When the ECM detects the near-idle crank speed, it operates the injectors again. If there's deposits on the injectors it will cause the fuel stream to spray to one side or in droplets (think of a shower head with calcium buil-up). This won't affect normal operating speeds because airflow will help distribute and atomize the fuel. When you're at/near idle, airflow is diminished greatly and atomization is reduced. This can cause missfires or even knocking due to late ignition of the fuel/air mix. Could explain the tendency to die when throttle is closed. This is especially true if the air cleaner was replaced at your service visit. The increased airflow might have thrown your ECM idle fuel adaptation off. Sorry this is so long, but I think both of these possible fixes are inexpensive and relatively painless. Take you time and do it right! Good luck!
P.S. if you decide to try an injector cleaner, I recommend Techron. If it can clean GM poppet valves, it can clean your injectors!
 

·
Super Moderator
Joined
·
22,106 Posts
.... I'm guessing there is no idle bypass....
Two choices - wrong guess! :p

There is and a control valve for the idle system (Idle Speed Control Valve)

From your description it sounds like the ISCV is actually trying to 'save' the idle - so may be more likely a fuel problem.

But start with some basic 'housekeeping' - remove the ISCV and clean the valve and the housing to make sure there is nothing obstructing it.
Check for vapor lock in your fuel tank - see how it runs with the gas cap open.
Check the spark plugs
Force an adaption process.

.... This is especially true if the air cleaner was replaced at your service visit. The increased airflow might have thrown your ECM idle fuel adaptation off. ....
This one has some merit - depending on how bad your old filter was.
They should have reset the trims and re-adapted it.

If you force adaption, that would address that fairly quickly however.
 

·
Registered
Joined
·
7 Posts
That makes perfect sense, DeCosse!:eek: There's no way the ECM will control the throttle valves. It can only sense what angle you apply the throttle at, either via TPS or air density. Debris at the blades can still cause idle concerns, though, because they never seal completely and the ECM programming has taken that into consideration. If they close too tightly (carbon build-up) the idle air bypass has to take up the slack in airflow. Follow DeCosse's advise on the bypass valve. But while your there, clean those blades, too.
 

·
Registered
Joined
·
57 Posts
Discussion Starter · #8 ·
Thanks you both for all the info. Hopefully all goes well. I'll let you know what I find/how it goes. Thanks again.

What does it mean and how do you force an adaption process. I am about to take it apart his afternoon. Also what should I clean the ISCV with? Hopefully you're able to respond to this sooner than later. Your help is appreciated.

Another question, I tried looking through the manual to try and find the ISCV, where is it located?
 

·
Super Moderator
Joined
·
22,106 Posts
ISCV is on left side of the TB assembly - you can see it as soon as you remove the airbox - it has its own clean air feed off the airbox and three hoses coming off the bottom to the respective TB's.

Clean it with carb/injector cleaner spray.

To do a forced adaption, see below

(simply needs to be idling at normal operating temp)

 

Attachments

·
Registered
Joined
·
57 Posts
Discussion Starter · #10 ·
Problem Fixed

Well DEcosse advice worked pretty well. My bike runs well like brand new. Thanks for everyone's input!
 
1 - 10 of 10 Posts
Top