ST4S electronics on an ST3 engine - Ducati.ms

danrduc · Jan 24th, 2012, 6:59 pm

Just curious about installing an ST3 engine in an ST4S chassis, and using the ST4s electronics and injection. I t is an 02 ST4S chassis and components.
Any problems that are obvious to anybody? I am not yet to familiar with the differences between the two systems,thought searting here would be a good place.

**Gearbox** · Jan 25th, 2012, 3:35 am

The engine on an ST3 is totally different so I cannot envisage that you could transfer without a lot of work , keep looking for a SH 4s is my recomendation.

Derek · Jan 25th, 2012, 4:54 am

It should be do-able, but - for '04 and '05 the ST3 uses the same non-linear TPS as the ST4s but from '06 uses the linear TPS which is non-adjustable, TPS reset being done from software and I wouldn't be sure that IAW59 ECU on the 4s has that capability and it would be calibrated for the non-linear one anyway. So you would need to make sure you used the non-linear TPS.
The fueling with the 4s ECU would probably be wrong for the ST3 and more importantly the ignition timing may be wrong as well. It may be possible to address this with a Power Commander but I'm not sure if these can alter the ignition. An ECU from an 04/05 ST3 should work but this could lead to immobiliser problems as they are coded to the dash, or an after market programmable ECU could be used - Nemesis (expensive) or Ignitech (more affordable).
Or you could fit the whole loom, ECU and dash from an ST3.

stryder · Jan 25th, 2012, 8:16 am

Quote:

Originally Posted by Derek

It should be do-able, but - for '04 and '05 the ST3 uses the same non-linear TPS as the ST4s but from '06 uses the linear TPS which is non-adjustable, TPS reset being done from software and I wouldn't be sure that IAW59 ECU on the 4s has that capability and it would be calibrated for the non-linear one anyway. So you would need to make sure you used the non-linear TPS...

I thought the 04 & 05 ST3 TPS was only adjustable through software as well. (?)

**Gearbox** · Jan 25th, 2012, 9:39 am

Aren't ST3's twin spark as well ?

**ST3S** · Jan 25th, 2012, 10:02 am

Yes, the ST3's us a dual spark motor, like the air cooled two valvers of that era. Interesting to note that they have since gone back to a single spark plug on the newer two valvers. All about emissions.

I installed a DP ECU from a 2004 ST4s in a 2006 ST3s. Ran great up until about 5,000 RPM, at which time the motor cut out completely. If I recall it came back on again at about 7,000 RPM. Not necessarily the ideal situation. Easy to fix by having the ECU reflashed to the 2006 ST3s performance ECU.

DuckMan · Jan 25th, 2012, 10:56 am

I'm thinking the last generation of 4S and 3S used the same ECU. The stock ECU that came in my 3S had the option to display "4S" on startup and had the controls for the adjustable headlight the the 3 didn't come with. I once changed mine to "4S" just to see if maybe there was a different fuel map depending on settings. I could tell no difference.

Derek · Jan 25th, 2012, 3:28 pm

Quote:

Originally Posted by stryder

I thought the 04 & 05 ST3 TPS was only adjustable through software as well. (?)

On the ST3 it may be adjustable through the software but it is a non-linear TPS for those years, the same as the ST4s

danrduc · Jan 25th, 2012, 11:13 pm

Thanks for the replies, things for me to think about and check into before going forward. Have to get an idea of total options and respective cost.
Good to have some knowledgable people to ask questions of, and not be trying to do things totally alone/independent always.
Thanks again

hnracing · Jan 31st, 2012, 1:43 pm

It will all depends on what parts you want to reuse from the ST4S.
The ECU can always be flashed with a suitable ST3 map.
But the type of TPS non-linear/linear must follow the ECU and the map.
So if you go for a 59M ECU and a ST3 map you would have to use a non-linear TPS like PF09. But if you go for a 5AM ECU and a ST3 map you must use a linear TPS like marelli PF1C or IPF2CB.
The immo can always be switched off