2006 Malibu Sunscape 23 LSV w/Monsoon 340 “Check Eng” at idle

[Davews]

I recently started to get an intermittent (the worst kind)  “Check Eng” fault while idling and the engine goes into limp mode.  I’m able to clear the fault by turning the engine off/on.  Sometimes one on/off cycle will clear it.  Other times it will come back 2-3 times in a row. It seems to happen mostly after the engine is at operating temps and it’s been idling conditions for a period of time.  Like while maneuvering into the slip after idling through the No Wake Zone.  Once I get it anywhere above idle, the boat runs great, with all temps and pressures normal.  This problem began to show itself after I had a dead battery.  Could it be related to the dead battery?)

Being an ‘06, I’ve not found a way to pull up any fault codes on the panel.

Does anyone have any suggestions on the cause or what to watch to help diagnose/troubleshoot this issue?

Thanks in advance .

 

 

[justgary]

1 hour ago, Davews said:

I recently started to get an intermittent (the worst kind)  “Check Eng” fault while idling and the engine goes into limp mode.  I’m able to clear the fault by turning the engine off/on.  Sometimes one on/off cycle will clear it.  Other times it will come back 2-3 times in a row. It seems to happen mostly after the engine is at operating temps and it’s been idling conditions for a period of time.  Like while maneuvering into the slip after idling through the No Wake Zone.  Once I get it anywhere above idle, the boat runs great, with all temps and pressures normal.  This problem began to show itself after I had a dead battery.  Could it be related to the dead battery?)

Being an ‘06, I’ve not found a way to pull up any fault codes on the panel.

Does anyone have any suggestions on the cause or what to watch to help diagnose/troubleshoot this issue?

Thanks in advance .

How long has it been since you did a full tune up (including plug wires)?

You can build a data cable and read the engine data yourself to see what's going on.

[Davews]

Thanks for the reply.  The “full tune-up” sounds like a good idea. Unfortunately for me, it’ll have to wait until the off-season. The boat’s on Lake Mead and with the low water level, it’s a challenge to launch/recover the boat. (Up to 4 hour waits on busy weekends!)  And, the shop we use is 25 minutes away in Vegas. In the meantime, we can get by with its current condition. 

[Tsumi]

Have an 06 Wakesetter 23LSV with the 8.1 having the same problems. Spark plugs, wires, and coil packs already replaced. Have absolutely no throttle when it is in limp mode. I do have a high fuel pressure issue (85-90 psi at the rail) and probable leaking injectors (key on drops down to 30 psi), but I doubt it's related.

Most searches have said that it is related to the throttle, either the throttle control itself or the throttle sensor on the engine. It can also be an electrical problem. I've noticed that the voltage readings when RPMs go up start about 13 volts at 1000 RPM and up to 14 volts above 2000 RPM, but will drop down to 12.3 volts when idling. Going to be attempting to replace the alternator before looking into the throttle.

[justgary]

9 hours ago, Tsumi said:

I do have a high fuel pressure issue (85-90 psi at the rail) and probable leaking injectors (key on drops down to 30 psi), but I doubt it's related.

Fuel pressure must be constant for the engine to work properly.

[Tsumi]

4 hours ago, justgary said:

Fuel pressure must be constant for the engine to work properly.

While true, I'm 99.9% sure it's not causing the check engine issue. Cold starts, it will usually run for 2-3 hours without issues. Once warmed up, it will intermittently alarm, sometimes immediately after starting and other times after a run is finished.

Limp mode that is a fuel or temperature issue will usually allow limited throttle. Every instance of limp mode without any throttle that I could find points to a throttle control related issue.

Edit: Also, to clarify, I have a consistent 85-90 psi at the rails while running, from idle to WOT. Key on without starting starts at 80-90 psi before dropping to the 30 psi range.

Edited July 24, 2022 by Tsumi