Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > Monsters > Monster S4 916 fires once but will not start

[dunlop0_1]

Only ever had a faulty TPS once which was on the 620. Even so the bike would run just didn't rev very well.

You may have already checked this but are all the connectors in the ecu plugs correctly seated? None of them have got push back.

When the air pressure sensor failed the bike coughed and spluttered, misfired and then died. It would attempt to start but be an absolute pig until it back fired big style and set fire to the air filters.

[carsbikesboatsplanes]

I also am of the thinking that only TPS and timing (CPS) will inhibit starting as when TPS disconnected, no spark. When air temp/press or water temp disconnected, same as before, will not start but fires once or sometimes intermittantly whilst cranking.
Pin push back, pin pull-off check ok today.
Supply to sensors correct at 4.8 to 5V
Output from air press sensor 4.5V... don't know if that correct but seems reasonable.
TPS primary coil 520 ohms, output 60 ohms idle to 600 ohms full throttle with no dead spots.
Water temp sensor 5510 ohms
Air temp sensor 3280 ohms
All resistances measured from ecu. Volts measured at sensors.
Supplies to ecu ok.
All earths ok
Tried independant supply to coil sticks and injectors from pump/injector relay output to ecu body, same result
Tried jury wiring ecu body 38 earth lin (sidestand eng kill) same effect
Injectors resistance 14.8 ohms from ecu
Coil stick resistance 1.7 ohms from ecu
Tried starting with one stick and plug out and comination of plug/stick in one cylinder at a time, confirm same effect and fires both cylinders with any combo once or intermittantly.
Am starting to suspect ecu even though effect is same with both my "racing" ecu and the flashed one (to bypass imobilliser). My original ecu confirmed no ign switching at all.
Insulation checks not done yet, only done so far with multimeter not megger.

[skidlids]

Coil driver outputs on the ECU are fairly easy to check with a diode tester, mine reads 0.514 when GOOD and reads 1.2 when duff.

[jerryz]

A wrongly set or faulty TPS would make low speed running and stalling very likely ,,so its possible that could also inhibit starting , also s4 is very battery sensitive they need a full charge

you dont have to splash out on Ducati coils Honda Cbr600rr coils fit and can be picked up much cheaper .

[carsbikesboatsplanes]

Happy Days, bike runs again after fitting another ecu, this time a stock one, together with its associated immobiliser (both used items) and the matching key.
So, the bike will fire once if the ecu is not compatible. The immobilser light was going out in 0.7 seconds so the key was recognised but the ecu didn't like the "racing" ecu supplied with my used Termi's or the flashed one I had borrowed. The original ecu I confirmed faulty using diagnostic software. It was "seeing" sidestand down and kill switch off even though those circuits/switches were fine.

So, when you think you've tried everything......go back to the original thought!

Thanks guys for all your inputs and interest.

[antonye]

Check the version numbers on your ECU - I expect the one that works was a 59M and one that didn't was a 5AM and the wiring loom/pin out is different between the two; the sidestand is the giveaway I think!

[carsbikesboatsplanes]

All 3 ecu's were 59M.... The original one was the one that sensed sidestand and kill switches in wrong position and appears an internal ecu fault. That one would consequently not allow any spark or injection.
The other 2 ecu's which allowed one spark/injection appeared not to be communicating with the immobiliser although both were meant to be immobiliser disabled. Incidently, the immobiliser appeared to recognise the key as it extinguished the light iun the correct 0.7 second.
Cheers.