Jump to content

Welcome to TheMalibuCrew!

As a guest, you are welcome to poke around and view the majority of the content that we have to offer, but in order to post, search, contact members, and get full use out of the website you will need to Register for an Account. It's free and it's easy, so don't hesitate to join the TheMalibuCrew Family today!

340 Monsoon Mid-range miss


Recommended Posts

wakerider701

Hey all, 

I have a 2004 Malibu 23 LSV wakesetter with the 340 monsoon. 1000 or so engine hours, and have been batteling a very intermittent misfire over the last two seasons. Has happened 1/2 a dozen times or so times in 5~ hours of surfing/wakeboarding

The bog or miss has always happened while surfing or wakeboarding. So 10-20 MPH or so (if I remember right we are around the 2500-3000 RPM range) and is very random when it happens ( doesnt happen ever time, sometimes after a hour or so of surfing, sometimes right away). When the bog happens there is a smell of raw fuel/rich condition. 

The boat has NO starting, idleing, WOT, or High speed issues. When the miss happens it will continue until we pull the boarder in the boat and do one WOT lap around the lake, this seems to clear out the engine and it will then run fine again at surf/wakeboard speed after it is cleared out. 

Things I have checked/replaced over the last two seasons trying to troubleshoot this: New distributor cap, rotor, spark plugs and spark plug wires. New Fuel filter, new fuel lines from tank to pump (return lines where NOT replaced). Checked fuel pressure while the bog/miss was happening and it was holding 60 PSI.  New Thermostat, New water pump, Fuel sample was checked for water (none found). The issues has happened over the course of a few tanks of fuel, different ambient temps, different lake temps, etc. 

 

Looking for any recommendations on what to check next, I hate to start throwing parts at it. Based on the fuel smell and fact that a WOT pull typically clears up the issue it seems to me that it is a RICH bog/miss. 

 

Only other issue the boat has is the low oil pressure alarm will periodically chirp on rapid acceleration/decel, the gauge cluster still shows good oil pressure and after some reading on this site it seems that issues is a somewhat "normal" condition. 

 

Thanks for the help. 

Link to comment

Have you thought about sending your injectors off to have them cleaned/match balanced?  Maybe one (or more) is sticking when under high load.  There have been several members here that have had good results by doing this.  And if nothing else, you can rule out injector issues.

Link to comment
wakerider701

Thanks for the feedback. I have somewhat discounted the injectors being: the misfire seems to be on multiple cylinders, and it starts/Holeshots/pulls strong on the top end. If I don't get any other tips I will see if I can find someone local to go through the injectors. 

 

Link to comment

A proper diagnosis would begin with a cylinder compression test, spark plug and ignition system inspection or spark test, then fuel pressure and injector testing. 

A quick cheat to find a cylinder not making power is an injector kill test.  On an engine with batch fires injectors, this can be done by running the engine at 1800-2000 RPM and disconnecting one fuel injector electrical plug at a time.  Working cylinders will normally cause the RPM to drop a very similar amount, but a faulty cylinder will cause the RPM to drop much less than the others.

Link to comment
wakerider701

Thanks for the reply csleaver, 

Like I said in the initial post the engine runs fine in the 1800-2000 range. all cylinders firing and no misses or bog. I'm confident that some cylinders are dropping out when I have the miss so what I need to figure out is why. Looks like I forgot to mention it in the original post but the compression on all cylinders is strong and within 10%. The original post states what ignition system components have been replaced and what the fuel pressure findings where. Do you have any specific inspections on the ignition or injector that I can perform? 

 

-Grant

Link to comment
formulaben

This is coming from left field, but I would consider replacing the coil.  Old coils can fail intermittently with heat (and demand) before total failure.  It's a lot cheaper than cleaning injectors.  And it appears you've changed everything else in the ignition system?

Link to comment
wakerider701

Formulaben, 

I'm thinking the same. For the price of a coil and Ignition Control Module I think its worth the gamble to spend the $100~ and not pull any more hair out. I had been thinking it was a fuel issue all along but I finally was able to get the issue to act up when I had a fuel pressure gauge on board and verified it was maintaining good pressure. I cant see it being a venting, anti syphon, line, pump issue if the pressure stays at 60 when the miss is present. 

 

Link to comment
formulaben

Chalk it up to preventive maintenance.  Fingers crossed it helps...I've seen a couple other posts here where the coil fixed the problem and I never would have gone there otherwise.

Link to comment

I have seen intermittent failure of ignition modules.  The original modules had a white temperature sensitive paint dot that would turn yellow when overheated.  I would often replace any original ignition module with a yellow dot to aid in the diagnostics of an intermittent spark issue.  The use of thermal insulation paste is important during replacement of ignition modules in the Delco distributors.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...