My GPRXP build

[John's truck]

So I’m a little unsure about base timing. I checked the piston at the absolute top of its stroke. Set the wheel so 0-TDC lines up with the aluminum block on the mid-bearing. Now, the Motec base maps say the crank trigger is at 304 degrees BTDC. Since I mixed and matched a 06 crank in an 04 PTO, I should be 7 degrees off of that, so either 311 or 297 depending on if it’s a retard or advance error. However, the timing light is hitting on 291 BTDC. I’m wondering if it’s a timing light error, or if the Microsquirt is reading the end of the trigger gap and the Motec was reading the beginning. I guess I can get another timing light and double check. And maybe delete the light bulb from the spark plug tester wire in case maybe it’s resistance is altering the signal

OR… I’m seeing error because the degree wheel is on the midshaft and there’s some slop in the splines going in to the crank…

[John's truck]

Well I just got a plain old HF timing light without all the digital brain crap and push buttons that don’t do anything. We’ll see if it agrees on where the TDC indicator lines up

[John's truck]

So the next side project… Microsquirt can’t control a stepper motor IAC, only PWM (pulse width modulation)… this also means that a completely electronic throttle is out of the question. SeaDoo of course uses an IAC. I don’t want to buy an adapter box, none of the ones I can find are waterproof/automotive, they’re all for interior stuff. So, IAC’s getting deleted. But I need to control air air idle. So either I use the throttle set screw, or I make a manual bypass idler. Since I haven’t found which car SeaDoo got their IAC from (yet) I haven’t been able to cross reference it to a pre-made piece. So, fabrication time. I traced the IAC base and glued it to some 10mm thick aluminum. I’m going to try doing this one in the garage, if it doesn’t work I’ll take the plate over to my buddy who has a little CNC router and do the bottom side (the 19mm circle for the O ring). Then I’ll just center drill and tap it for whatever size wheel-knob bolt I can find at the store and put a vacuum cap nipple over the threads at the bottom.

[John's truck]

Worked up an STL for the IAC delete. I’ll print it in plastic and see if it fits, then convert it to an SVG line file for my buddy to router out of the 10mm aluminum plate. Then tap the center of that for the bolt.

[John's truck]

Well my printer broke, so I ordered a new bed level sensor. And then the ski’s kill switch started acting up, so I ordered a new one and I’m going to change some stuff with the way it’s mounted and wired.

And I got to thinking. The factory cam sensor setup was fused 12v, signal wire, and sensor ground. That’s not being used anymore. Microsquirt has an available Flex input, for an ethanol content sensor. So I’m thinking I’m going to ordered up a sensor and pigtail and just wire it up in place of all the old cam stuff. Not that I’m planning on running e85, but it will at least give a comp table for ethanol content. And my OCD can’t handle a live but un-used fuse in the panel.

I also need to figure out where I want the sensor in the fuel line. Supply, to the rail, or return from the regulator

[John's truck]

looking through the installation and setup manuals, this looks pretty straightforward. Make sure the sensor scaling is correct, and then adjust target AFR and ignition timing comps based on ethanol percentage.



Now the marbles are moving in my head, I’m trying to decide if I should mount the sensor on the RRFPR return to the tank (will always have fuel circulated) or on the inlet to the fuel rail. I seriously doubt the cam sensor plug will work for the Flex fuel, so I’ll have to splice the harness regardless. But I guess I need to get my hands on the sensor and decide if I like the hose routing with it mounted in the very front of the ski, or on the old Yamaha powervalve servo bracket better.

[smokeysevin]

I think I remember reading that the sensor is supposed to go on the return but I don't remember why.

Sean

[John's truck]

I think I remember reading that the sensor is supposed to go on the return but I don't remember why.

Sean

Since I have a factory dead end fuel rail, it probably should be right before the rail. The fuel pump is constantly circulating through the RRFPR and back to the tank, but the engine would have to burn all the gas in the rail and supply line to start seeing the fresh stuff in the tank. So the idea is the sensor sees whatever the injectors are going to see. Which kinda makes sense to me, so I’ll probably put it on the YPVS mount. If I had a pass through fuel rail, which I probably will someday, I’ll feed the rail from the back, exit up front through the sensor in the return, and then through the pressure reg and back to the tank. Then I only have to change hose routing and don’t have to re-mount any large components of the system

[smokeysevin]

I think I would probably run it on the discharge to tank side of the rrfpr in that case. On startup at least, you will always have a reading from the tank vs whatever was left in the rail/rail line that way.

In reality, it is probably fine either way.

Sean

[John's truck]

Prototype of the manual idle air adjuster. The refined version with more walls and infill is printing right now. I need a longer center bolt, then I’ll put it on the throttle body. Im just going to use this at idle, and I’m going to send a 2d drawing to my buddy to cut out of the 10mm aluminum. I’ll end up tapping the center threads and using a lock nut to keep the bolt from rattling in or out and changing airflow

[John's truck]

Well I’m in a printing mood, and the replacement killswitch showed up today. I want to get rid of the flat metal plate it’s been mounted to, and figure out a way to secure the cabling in multiple places before it ever sees flex. So, busted out the calipers and Tinkercad

[John's truck]

Quick and dirty print. I’m going to add a place for the wires to clamp to, and then dehydrate the filament overnight and then reprint it tomorrow with all the walls and infills to make it strong. But it’s solid right now with 4 walls and 20% infill. So that’s a good sign.

[John's truck]

Finished the solid print of the kill switch tower, with some cable clamps added. And I made a little round piece to keep everything from chafing on the side of the plate. The large leg slicer plate is gone, thank god. No matter how I turn the handlebars, the wires don’t get pulled or tweaked in any way. 100% better than the old mount

[smokeysevin]

Looking good. All the little detail things are so satisfying to get squared away.

Sean

[John's truck]

Looking good. All the little detail things are so satisfying to get squared away.

Sean

Thanks, this one feels like “one step forward, 2 steps back” since it’s a problem I found with the ski shutting off when the handlebars got turned. But at least it’s fixed and I like the fix better than the previous setup. So maybe it’s 1 step back, 2 steps forward.

Just checked now, the ECU wakes up so I need to get back to setting timing and making sure I have priming pulse and enrichment close enough to get the engine started so I can log some stuff