Buell EFI troubleshooting

BUELL EFI

TROUBLESHOOTING


We all know that EFI equipped ​Buell motorcycles don't always run properly.  Over the last few years, finding a Buell savvy technician with the proper diagnostic tools and abilities is also getting harder to find so many Buell owners find themselves trying to take matters into their own hands.  Needless to say, it's best to utilize proven tools and processes since replacing parts at random or because of an online "expert's" recommendation usually leads to wasted time and money.  Fortunately, you can perform extensive diagnostics and troubleshooting procedures using common tools, an Android device, and a BUELLtooth interface.  This means that diagnostics and repair of your Buell motorcycle is easier than you think.  This page is not only for use when a bike is running poorly or not at all, but it can also be used as a preventative measure or to make a bike that is running well, run even better.   

 

PREREQUISITES

 

Before beginning, you should ensure that some obvious, and maybe not so obvious conditions are met.  This includes, but is not limited to;

  • Clean and fresh PREMIUM grade fuel in the tank

 

  • Clean air filter

 

  • Static timing set correctly

  • A matched tune for your configuration installed on your ECM

 

  • View and record any active or store trouble codes.

 

*Note:  Don't replace a part just because a trouble code is associated with it.  Often, a Check Engine Light is caused by a sensor detecting a problem, not causing it.

 

COMMON ISSUES + FIXES

The following is a list of common things to do or look for as well as instances that have been experienced by others:

  • TPS Reset.  ​Lets just get this out of the way!  If you have replaced your ECM or loaded a new file this is something that needs to be done.  It's also not a bad idea to do this once a year or so on pre-2008 models.  However, it doesn't fix nearly as many problems as some people think it does.

  • Know your AFV and what it means.  This is often how you check the pulse of your motorcycle and decide your next course of action.  Without this information, you are operating blind.  You can also make changes to the AFV settings to help isolate issues. 

  • Intake leaks.  These bikes are notorious for having leaking intake seals, just like their HD cousins.  Due to the age of these bikes, its a good idea to replace the seals as a preventative measure.  The procedure isn't too difficult and the parts are inexpensive.  This is arguably the most common cause of "high AFV".  

  • Check your grounds.  So many problems are caused by bad grounds as these bike age.  There are several ground wires, splices, and mounting points.  Pay close attention to where these grounds mount to the frame and the bonding wires between the frame and engine.  A bad connection at any of these places will wreak havoc on your EFI system.  Bad grounds are known for causing a laundry list of trouble codes and/or intermittent issues with sensors.

  • Bike runs well at idle and low throttle, but lacks power at higher throttle settings, or cuts out completely.  On XB models this can be due to an improperly installed intake pipe which collapses at higher throttle settings. 

  • Fuel flow issues.   These can go unnoticed for a long time because the Buell ECM is able to compensate for low fuel pressure by increasing the Adaptive Fuel Value (AFV), up to a point.  If a fuel problem is suspected you should check this AFV setting immediately.  If it is significantly higher than 100 you should measure the fuel pressure which should be ~49 PSI.  Also, after a repair, the AFV must be reset back to 100.

  • Erratic or inaccurate engine temp.  This can be caused by a loose or defective Cylinder Head Temp Sensor (CLT), or a chafed sensor wire.  The ECM will adjust fuel delivery based on this data.  Using the live data page of Ecmdroid allows you to see sensor data in real-time as well as temperature compensation percentages associated with CLT and Inlet Temp Sensor (IAT).

  •  Inaccurate TPS reading caused by broken throttle shaft.  XB, X1 and S3 models have a common problem caused by a broken throttle shaft at one of the throttle plate mounting holes.  This causes a significant offset between the actual throttle position and what the TPS is reading.  Check for this before buying a TPS or other suspect sensor.  You may need to clean the area to perform inspection.     

TROUBLESHOOTING FLOW CHART

REVISION MOTO's Tutorials page has a list of guides that will help you perform the tasks listed in the chart below using Ecmdoid and a BUELLtooth device.  Refer to the applicable service manual for in-depth procedures, tolerances, wiring diagrams, etc.  These can be found on our Resources page. 

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