2002 150dxtlra ox66 idle and timing questions

[captainj]

I was checking the timing at idle with engine on flushing attachement.
The timing was around 2 degrees atdc. While idling the the engine would idle up about 100-200 rpm. When this would happen I noticed that the timing was advancing about 2 degrees. Could this be caused by the flushing attachement causing the CTS to adjust to the cool water from the hose. Does the CTS adjust
timing continueously. I ohm out the CTS and checks good. Timing is advancing on starts up like it should. Thanks

[DennisG01]

I'm sure some more knowledgable people than me can correct me if I'm wrong, but... Most times, a 2-stroke doesn't idle well on a flush attachment because there's no back pressure on the exhaust. I would think this would be hard to do, accurately, unless you're in the water (or a tub). Mine idles a bit high on a flush attachment, along with pretty much every 2-stroke that I've ever had (or can at least remember).

[captainj]

Thanks Dennis
Yes, mine runs at a higher rpm than it does in the water. But the same sympton with the idle ranging up and down about 100-200 rpm as is was when it was in the water. My concern is should the timing be changing back and forth. All the lakes here are closed due to floodiing. The TPS voltage remains steady at .57volts and doesn't change when the timing is bouncing around. Maybe Rodbolt will chime in he seems to know everything. I know that the CTS changes timing not sure what other sensors affect timing

[DennisG01]

I don't know the rest of the answer. BUT... thinking through this... if the temp of the water would change the RPM's (make it fluctuate like you're saying), then there would be a lot of people complaining to Yamaha about their idle RPM fluctuating when the boat/engine is in the water as there's many, many people running in cool water. Or, at least, that makes sense to me! So I would think that the water temp doesn't anything to do with your issue. Sorry I can't give you a better answer, though.

[bajakeith]

uhh-huh

most will run a bit faster out of the water.. and the idle timing is advanced when she's cold... Sorry, I don't understand the Question ??BTW, Almost all Two Srtokes, the idle speed is adjusted by advanceing the timing,, Not by carb opening

[captainj]

The idle speed is not my main concern. It is the timing jumping around. I understand the timing is advanced on cold start. I was able to lower the engine in a large container and the engine warmed up and the thermostats or open. The timing when warm goes to about 2 degrees atdc. But will advance to tdc and back to 2 degrees atdc and back and forth while running which changes the idle speed.
Rodbolt knows alot about the sensors and cdi operations that are not in my manual. Maybe when he gets a chance he will give some advice.
I am leaning towards the CTS but it checks ok. Maybe a in-range failure?

[rodbolt17]

if it runs well in the water unrestrained I would not sweat it.
it is an EFI, EFI constantly corrects the idle speed.
on the OX66 this is accomplished by varying the injector ON time AND the ign timing.

[boscoe99]

most will run a bit faster out of the water.. and the idle timing is advanced when she's cold... Sorry, I don't understand the Question ??BTW, Almost all Two Srtokes, the idle speed is adjusted by advanceing the timing,, Not by carb opening

Did you overlook the OX66 EFI and HPDI two strokes?

How is the timing adjusted on an HPDI?