Hi I have an ST4s which has been running perfectly but sometimes I have an issue starting it on my way back to work. Got stranded once and blamed the immobiliser (which was playing up in other places as well). ECU reprogrammed without immob. immob disconnected and problem solved. Til next time I got stranded. Pump priming oK, engine rotating OK bike not starting. Fuel not seeming to go through. So: - removed the alarm with a new wiring loom - got injectors flawed by JHP - new plugs, coils checked and good - Fuel filter changed - ECU proved to have a problem and changed it (though could have been in the process) - basically the only things I did not touch are TPS and crank sensor. Problem occurred again though only in the car park at work. Starts immediately at home. It is intermittent (did it twice in 2 weeks) and bike rides otherwise OK though I have a small issue sometimes. I am starting to wonder however if there is an issue with the car park. A mate told me that he had issues with his alarm in there and there are some antennas on some of the pilars. Re issue when riding - When hot (like 100C) it seems like the TPS plays a bit. A bit like nothing happening at initial small opening of the throttle sometimes. Then a cough. Then it carries on or sometimes it stalls. So questions: - the small issue when riding - does it feel like the TPS needs changing or just resetting with the whole balancing / fueling done again. I think that I am a bit lean. - the issue when starting at work - Does anybody know if the 5.9 ECU or any other componentry of the bike is subject to electromagnetic or other Electric interferences?
First question, what year is it? There was a problem with the ECU's on the early 4S's and the symptoms you describe match mine. If you changed the ECU for another for the 2001 / 2002 bike, chances are you've simply bolted a new version of the problematic ECU back on. The fix was to use a 2003 on ECU and to ignore the fault code which shows up where the ECU is looking for the starter circuit ( this circuit on the earlier bikes is totally separate from the ECU ) Neil at Cornerspeed sorted mine.
I would be surprised if it was an electro-magnetic problem..........more likely a radio frequency issue. If it were electro-magnetic, there is plenty of stuff in our homes with high electro-magnetic emissions. For example I have HV 400,000 V cables traversing my property and I have no issues from them because the maximum they are chucking out is 20 microtesla, whereas the Earth's natural reading is 50 microtesla. Your microwave oven chucks out about 30; bedside clock alarms about the same; and your vacuum cleaner will produce 300 or so. NRPB recommendations for workers on HV lines etc used to be 2500 microtesla; I believe it is now 3000. Electro-magnetic emissions die off very quickly over short distances........So if you were say, right underneath something thet was producing 20; by the time you had moved 50 metres, it would be down to about 1 or less. However, try parking your bike as far away as possible from the antennas........RF and the electric field doesn't die off as quickly as the magnetic field. Very similar problems were found with a Nissan car dealership where a new mast was installed which prevented all the remote controls from working because it changed the rolling frequencies of the remote systems. AL
There is some (anecdotal) evidence that certain radars used on airfields can have an effect on vehicle ECU's. I would suspect that any electronic device can be affected by the right sort of RF transmissions, so there is a possibility that it is the aerials that are causing the problems on your bike. Simple process of elimination - park it somewhere else for a few days and see if it makes any difference. Any idea what the aerials are actually for, or the frequencies that they operate at ? (Logically they could just be receivers, not transmitters, so may be having no effect at all...).
So I thought that I would give a final update as we seem to have come to the bottom of the issue. Many thanks to Chris, Nelly, Andy, etc. for tipping up with advices. and the problem was.... (drum roll)... Failing crank sensor. Chris had a brilliant idea to question the engine / ignition relays. I changed them hoping to solve the issue. Bike worked for a while and got stranded again. I also uploaded new maps making the starting easier. The last throw showed no further luck once I repatriated the bike back to base. This ruled out the antenna system in the parking. The very confusing element was that the bike would squirt fuel in the Throttle bodies but would not ignite any sparks. So with a sensor fully gone, none would have worked. But with a sensor partially gone, some timing teeth might still be picked up. Changed the sensor and bike starts. Change back the sensor and it doesn't. I think that we have gone to the bottom of the issued now.
