• This site contains eBay affiliate links for which Sea-Doo Forum may be compensated.

2003 4Tec sportster. Upgrading from Siemens to Bosch

davus

Member
Hi Folks.
I just wanted to start a bit of a story about the journey im planning on embarking on.

I have a 2003 Sportster 4TEC. Its a 155 normally aspirated engine. As soon as i bought it, I started mentally toying with the idea of upgrading it to a later 2009+ 260 Bosch driven setup.

IE: Replace the Siemens ECU with a Bosch ECU, and replace the engine with a later model block accompanied by a 260 super charger.

Ive been chasing a stupid annoying gremlin of late, where the boat will randomly cutout whenever i start throwing it around a bit.

Rather than spend endless hours trying to diagnose or chase an intermittent error that only happens on the water in certain conditions (IE not repeatable in the garage), ive decided to gut things and start from scratch.

Im going to attack it in two different stage.

Phase 1 - Upgrade the wiring and some of the mechanicals to a 155 normally aspirated setup using the Bosch ME17.8.5 ECU (Used on the 2009+ Seadoo skis). This will involve changing the inlet manifold and throttle body, along with adding a TOPS switch, updated injectors, and a bunch of wiring changes. This will allow me to prove i can run from the new setup/ECU, whilst keeping the reliability of the 155HP normally aspirated setup.

Phase 2 - Once the new setup has settled in, I will change out the PTO cover, Injectors and the ECU firmware (keeping the same ECU hardware) to modify it to a supercharged engine. I intend to keep the "Internal" intercooler (inside the inlet manifold) purely so i dont have to worry about finding a mounting place for the external cooler, as well as related piping.

So - This is my plan!. I havent started anything yet, and i havent given myself a real time limit, but wanted to share my story.

If anyone has any relevant info to add, or questions, im all ears. I love to be challenged on my ideas, so please dont be afraid to by inquisitive.
 
Hi folks.
So update to the story. Instead of doing the phased approach, i went straight for the 260 supercharged engine.

- Wiring harness has been swapped
- Throttle lever upgraded from manual cable to fly by wire throttle trigger
- Installed a spare 260 engine i had.
- Disabled IBR in ECU (still running manual reverse bucket)
- Upgraded driveshaft from older thin shaft to later thicker shaft.

Engine is now in and running. Did a water test yesterday, and ran perfectly. No issues at all.

Still to do:

- A bit of fiberglass / plastic work to mount the gauge cluster
- Figure out how to backlight the cluster (night fishing)
- Figure out a solution for the mode / set buttons.
- Figure out how to delete OTAS system (at the moment I've just left the OTAS sensor in there, which feels like a waste)
- Prop option is all wrong. Lots of cavitation on takeoff.
- Upgrade from internal intercooler to external intercooler.

Fun times!
 
Hi folks.
So update to the story. Instead of doing the phased approach, i went straight for the 260 supercharged engine.

- Wiring harness has been swapped
- Throttle lever upgraded from manual cable to fly by wire throttle trigger
- Installed a spare 260 engine i had.
- Disabled IBR in ECU (still running manual reverse bucket)
- Upgraded driveshaft from older thin shaft to later thicker shaft.

Engine is now in and running. Did a water test yesterday, and ran perfectly. No issues at all.

Still to do:

- A bit of fiberglass / plastic work to mount the gauge cluster
- Figure out how to backlight the cluster (night fishing)
- Figure out a solution for the mode / set buttons.
- Figure out how to delete OTAS system (at the moment I've just left the OTAS sensor in there, which feels like a waste)
- Prop option is all wrong. Lots of cavitation on takeoff.
- Upgrade from internal intercooler to external intercooler.

Fun times!
Have you posted a YouTube video or anything, anywhere showing your work?
 
Back
Top