I have been battling for some years to make the ST4S a reliable starter. I have replaced everything in the starting circuit. A while back I set up the fuel and she fired up well but now she is back to her old ways. My questions are as follows A Would a battery discounted reset the ECU fuel setting? I know some ECU’s can reset their BIOS in some cases B When she fails to start she does fire a little but sounds like she blows herself out. Plugs were black but that could be the result of may failed starts. Air bleed screws are around ¾ to 1 ½ out. Should I take them out more to lean the start up a bit?
Have you had the bike connected to any diagnostic software, and are there any fault codes? Can you see if the temperature sensors are reading sensible numbers? There are two, one for the dash and one for the ECU - you could try swapping the plugs between the sensors and see if it's any better.
Thanks for the ideas. I have fitted new sensors a while back. Also I checked errors on the ECU and found nothing.
You say you have replaced everything in the starting circuit? I presume you have changed the cables to proper aerospace quality ones, or at least new low spec ones like the originals before they deteriorated? If you haven't changed them at all the problem will more likely lie here. Info at www.exact-start.com Link here for 'Forum Subscriber' discounts http://ducatiforum.co.uk/threads/exact-start-hi-cap-cables-range-and-forum-discounts.36761/
Thanks for the pointers on the battery leads guys. I fitted new ones about 3 years ago and doubled up the leads and starter earth I am going to have another look as it is doing what it did before I set it up (when it started very well) I may remove the TPS and see if it is working correctly across it's full range.
Generally leads increase resistance after 2 or 3 years unless high quality fusion crimped and fully sealed :Angelic: but if you doubled up on all leads it should still work. If you need a TPS after your investigations give me a shout :smileys:
Hey Johnny, I've battled issues like yours before though mine was only fairly infrequent. But it did that cough and kick-back thing and that was it. It generally took a full battery charge and disconnect of the positive lead for a good hour before she would contemplate starting again. I did a fair amount of research and people said the ECU was dying and replacing it would sort it out. I got another ECU and looked into having it cloned with the old one, but luckily I consulted someone before I did. The two guys who used to run the Irish distributor workshop years ago set up on their own and one of them was the electronics guru. He replaced the immobiliser on mine when it died. I described the whole thing to him, and below was his response. Mine was also doing a weird thing where sometimes, with the full headlights on and at speeds above 100kph, flashing the high beam would make it drop onto one cylinder. Only turning off the lights completely, throttling off and then on again brought it back. "It does not sound like an ECU problem to me. I might not be 100% right, but most of the time ECU does not act like that. They either work or they don’t. You lose a cylinder for good (injectors, coil...) or it could be when it warms up, misfires, ECU errors, bad TPS readings... I really think you have a fault in your wiring somewhere. These faults are the worst one to find. You could try to find a cheap 996 Biposto ECU to put your mind at ease if you really want to go the ECU way first. It should start, it might not run perfect, but it should give you a good indication if the fault is cured. 996 do not use immobiliser, so it should work. I would find the wiring diagram and go through the whole loom. Start with the fuel pump relay. It supplies +12volts to the injectors and the coils as well. Check the wires after the relay (brown / white), There is a splice inside the loom for them which can rot. Same things for the earths inside the loom, they all tie in a joint. Same for the 12v before and after ignition. Make sure all the earths are good (ECU to loom, to engine, to frame, to battery). Check the ignition relay too, as they give trouble. All these jobs are time consuming but they do not cost anything. So if I was you I would go for that first if you are any way handy at the electrics. If it acts weird with different loads on the system (light, clean connectors...) I am pretty sure it's not the ECU." I found the earth splices were corroded, and I changed all the relays and that pretty much sorted it for me. A
Sorry for the late reply Ascalon. I missed the replies as I had PC trouble. I have swapped out the relays and buzzed out key parts of the loom (Injectors/coil) From what I can make out she is running on one pot. I have fuel and a spark but the toy town spark checking tool I have appears to show a weak spark. (could be just a poor tool) I am close to giving up. I can get an ECU loan so that probably my last point. I shall check valve too
