2007 VLX Misfire issues

[Blyon70]

13 hours ago, MadMan said:

Have you tried swapping injectors between #7 an another cylinder to see if the problem follows the injector or stays with #7?

I pulled all injectors and cleaned them. Installed them randomly back in. 1 in 8 chance injector 7 made it back to position 7. I highly doubt it but probable. 

Update: Performed a test light test on the power side of injector 7. It lit up and even blinked when trying to crank the boat. Therefore, I have power but can't verify that it is working under load. The only time the boat goes in to limp mode and throws a code is when I'm powering up to get on plane. When at idle I have no issues. I've replaced the pcv valve, plugs, plug wires, cap and rotor. Performed hot and cold compression test that checked out at 180PSI. Pulled the fuel rail, cleaned injectors and tested the power side of the injectors. Don't think fuel pressure is an issue as the problem is isolated to cylinder 7. I don't cam angle is an issue either as the misfire originally bounced from cylinder 5 to 6 and finally landed on 7.  At this point I have no idea what the problem is. Looks like its going to the dealer 

 

 

[MadMan]

You could try shorting the non-power side of #7 to ground or just unplug that injector. The run it.  The MEFI should detect it and set a fault.  If it doesn't, there might be a problem with the harness or the MEFI itself.

Edited March 1, 2017 by MadMan

[ski40mph]

The problem is not isolated to cylinder 7. It was 5 and then 6 and now 7. What causes misfires to change to different cylinders?

[Blyon70]

On March 1, 2017 at 9:13 AM, ski40mph said:

The problem is not isolated to cylinder 7. It was 5 and then 6 and now 7. What causes misfires to change to different cylinders?

It is now isolated to the cylinder 7, for the past 6 months. Misfire to different cylinders would fuel filter, trash in lines, injectors or on the spark side. I've replaced and checked everything on the spark and fuel side. Maybe unhooking the battery and letting the ECU relearn might help. 

[csleaver]

The cam angle can only be checked with rinda diacom software on a pc hooked up to the obdm plug on the motor wiring harness.  It is basically the engine timing. The cam sensor is located in the HVS (distributer) and is adjusted by losening the HVS hold down bolt and turning the HVS.  The spec is 705 +- 5 degrees at 1200 RPM.  Improper timing is one thing that can cause a misfire.

[JustinOSU]

Have you checked the engine timing?

[BEN307]

Hey.

not sure if its got the same distributor but i have an 05 with the hammerhead engine and your symptoms seem just like mine and my problem was the ignition control module in the dizzy.

my part comes up on ebay if you search inboard gm ignition control module and it was only about $55. But like i say your model might be completely different being 2 years newer.

good luck with it mate

[Blyon70]

Update: I found that the 4 bolts that hold the prop shaft coupler on were extremely loose; barely hanging on. With the 4 bolts loose, the coupling had play in it while rotating the shaft forward and reverse. I've tighten those bolts up and will shim check tomorrow.

I would think that this is the source of my problem. While on the fake-a-lake, revving up to 3k plus RPM, the misfire and engine fault does not present itself. However, when attempting to get on plane, or anything above 2k RPM in the water, the misfire 7 and engine fault presents itself. If I putt around at 1200 RPM, no misfire. I think the knock sensors are picking up the vibration caused by the loose coupler and placing the engine in limp mode. 

 

[skurfer]

Hope you are right, let us know

[Blyon70]

Update: Well my theory on the prop shaft was blown out of the water. The misfire was still present. Time to go to the mech. I assume computer issues or sensors. Don't have the correct tools for this. Will update the thread once I have a resolution. 

Edited June 6, 2017 by Blyon70

[Blyon70]

FINALLY got this thing running properly about a month ago and come to find out I'm a dumbass. When I replaced the fuel filter last season, there was supposed to be a rubber gasket on the end of it. It never made it on there. Debris flowed right past the filter and straight to the injectors. I had the injectors bench tested and cleaned. BINGO!!! I've had 30 trouble free hours and the boat runs like a well oiled machine. 

If anyone has misfire issues on your Malibu around this year model, feel free to pm me with questions. About an expert on working on this thing now. 

B

[Bradbalon]

Hi Blyon70,

I have a 2013 VTX.  The odd time I have the boat weighted up, in cruise, with s surfer behind, and all of a sudden the boat kinda misses or hesitates and abruptly kicks out of cruise.  The boat speed drops from 10 mph to 5 mph and my surfer nearly flies into the boat.  I thought it might be a fuel issue so I replaced the filter. Seemed to work for a bit, but on the weekend it did it again.  Any suggestions?

[JasonK]

Good news! I wonder if my filter has the rubber gasket. I haven't changed the fuel filter yet, but I just got the boat last fall.