Strange SMIS Display at shutdown

[rogerar]

Checkered, blue or purple lines, last time it happened it was the IAC, now it's just missing randomly and then the weird display at shutdown.

Anybody? The dealer ran an SDS check yesterday, no apparent problems,
Thanks
Roger

[rogerar]

Whoops, it's a 2011 90A.

[Harper]

Not sure what you mean by "missing randomly," but mine displays the horizontal purplish blue lines on every shutdown. I assume it to be normal since I experience no problems with it.

[rogerar]

Very interesting-random miss means a cylinder is not firing, but not the same one every time. Thanks for your reply, the only time I've seen them is when the motor has a problem with no diagnostic code.
Ah, computers-great when they work impossible to fix.
Thanks
Roger
I am still working on this problem.

[rogerar]

It's more than lines, the bottom half will turn solid blue, then horizontal blue and vertical purple, then the lines you refer to which are not normally there on mine. I have also gained a vertical permanent(?) purple line on the diagnostics page, and since the SDS check now have 2 purple lines on the trim page. When disconnected from engine, they go away along with data, but the gauge is powered up by the ignition.
Roger

[rogerar]

Also dealer said SDS indicated too fast idle(never been fooled with), and my SMIS reads too much gas going into cylinders, and the idle rpm jumps around so fast you can't see it, 650, 700, 750rpm flashing rapidly. This engine has been babyed for all of it's 677 hrs., Never a problem except IAC replaced 2016 under warranty.
Roger

[Harper]

Okay, didn't know you were referring to the motor when you said random miss. You were talking about the SMIS....

[rogerar]

Working on the problem, display now includes different patterns and even a checkerboard! I checked the resistance of the IAC according to the manual after I had been working for an hour or so with the motor on and off. The ohms were nearly twice what the manual calls for. Then this evening, when I was cleaning up,(hours later) I checked again, all were at 34 ohms-the top of the acceptable range. I then reconnected the IAC and turned on the key. I checked again. the resistance had gone up. I reconnected the IAC and turned on the key for around 5 min. and turned it off and checked the resistance again-at this point it's going up an ohm every 2 minutes or so, they were out of spec. Is This Normal that the IAC resistance goes up with the ignition on, then stays there long enough for me to disconnect and check it again?
Help
Roger

[rogerar]

Got the SDS printout, how can I post pictures?
Thanks
Roger

[Harper]

Click on the little camera lower left, upload the picture from your files. Type your posting.

[rogerar]

Here'sDSC00181.JPG

[rogerar]

This is a lightly used 2011 motor with perfect maintenance and no problems except the IAC was replaced in 2016 under warranty. The idle is too fast(never been touched). The timing is off by 9 degrees(never fooled with). The IAC is 20% over max. duty cycle, almost everything is wrong.
This has always been a smooth dependable engine, now it will hardly run.
Any guesses-Maybe flywheel key? Timing chain jumped a link?
I am doing a compression test tomorrow-the Dealer's mechanic insisted, and he's stumped. He's the best troubleshooter in town as far as I know.
Thanks
Roger

[rogerar]

Won't stay running today, cold compression test reveals 210 lbs in all cylinders.
Roger