Weird Beep Gremlin 496Mag HO

[Bootkie2]

We have an 06' 496 mag ho on our Formula 260. We were out cruising over the 4th and on our way back started to get some beeps and engine went into guardian. We had to putter home. Since then the problem hasn't really persisted and we've put another 1.5 hours on the boat without engine going into guardian. Though we've been getting a strange beep while idling (engine revs and then reduces RPMS for a few seconds). We finally had it plugged into merc diagnostic tool with a merc tech. (It's wasn't a 3rd party scan tool) We had the boat idling at 1K RPMS while plugged into the tool and then the boat beeped again and the computer reduced the engine down to 700RPMs without anyone touching the throttle but nothing in the data suggested any weird fault codes. The only strange reading was the duty cycle fluctuating to 100% (and then there were some duty readings all over the place) at idle. The computer didn't capture any weird read outs from our guardian event the other day on the 4th either. The engine has been running great and all the boat vitals are reading out normal. This is a strange one. What to do? Merc is saying the only way to try to capture this event is by driving the boat while plugged into the scan tool and hope that the guardian event that happened the other day at 3100 RPMs happens again. How in the world did the Merc software not catch this guardian event in the freeze frame? Is paying someone 100$/hr to try to get the boat to go into guardian while out on the open water the only approach? Seems crazy. Has anyone had this happen?

 

[tpenfield]

:welcome:

I have not had this happen, but I decided a while ago that paying a one-time amount of $500 to the diagnostic software company (www.rinda.com) was better than continually paying $100 an our to a tech with the same software.

So, now when bad stuff is happening with my engines, I can hook up the computer (laptop) to the engine and take the boat out for a spin while recording all of the data from the engine controller (ECM) and then play it back later, or even email it off to someone with more expertise than me to take a look.

Depending on the age/version of the engine controller, I'm not sure how much actually gets recorded, other than codes. The new versions are certainly better than the older ones. I happen to have the first generation of the controller (MEFI-1) so the data from my engine(s) is pretty basic.

If you are so inclined, you may want to look into getting the RInda/Diacom software for your engine.

 

[alldodge]

Agree duty cycle issues are hard to discern, suggest removing the IAC and clean it and the area around it. If it starts hanging things change fast.

The most probable cause for guardian mode is the water pressure sensor

The diacom is best bet

Edit: just realized your on the Formula site

 

[alldodge]

guardian event that happened the other day at 3100 RPMs

You know if your tachometer is a bit off and its happening closer to 3500 rpm then it could be the in gear switch. the motor thinks its in neutral

 

[Bootkie2]

I wanted to close this out so I am not one of those people who leaves you hanging (and maybe it will help someone?).

Finally had some time this summer to get the boat sorted. The IAC Valve was stuck at 100% open and the muffler was filthy (replaced IAC and Muffler). Also discovered a porcelain crack in plug #6 (current was leaking and causing the computer to go haywire). On top of that I also discovered some current leaking from Coil #1. With all of these issues it's hard to tell what was making the boat act up into limp mode but it's running fine now with New plugs, coils, wires, and IAC(+muffler). Getting close to 50hrs we put on it this summer so far.

 

[GA_Boater]

I wanted to close this out so I am not one of those people who leaves you hanging (and maybe it will help someone?).

Finally had some time this summer to get the boat sorted. The IAC Valve was stuck at 100% open and the muffler was filthy (replaced IAC and Muffler). Also discovered a porcelain crack in plug #6 (current was leaking and causing the computer to go haywire). On top of that I also discovered some current leaking from Coil #1. With all of these issues it's hard to tell what was making the boat act up into limp mode but it's running fine now with New plugs, coils, wires, and IAC(+muffler). Getting close to 50hrs we put on it this summer so far.

Thank you for the update, Bootkie2. :thumb: