Issues with my brand new 2022 350 Mag MPI's!!!

[MrKulio]

I overhauled/repowered my 2005 300DA over the winter. 2 brand new 350 MAG MPI's, 2 new transom assemblies, rebuilt upper units and the lower units are 2yrs old. Running Bravo 3's 2.2 with 22P props.

Just broke them in at 20hrs last week, changed the oil, checked all the fluids, and finally had a chance to open them up! Starboard is lacking power after 2400 RPM but will eventually climb once on plane. Port is running like a champ and will continue to climb to 4800 RPM with very little hesitation.

I've been working with the company where I purchased the engines and here is what I've done so far.

• Replaced in-line fuel filter
• Replaced water separator
• Replaced all 8 spark plugs
• Replaced cap and rotor
• Replaced wires
• checked the siphon valve (opens and closes with 12v ignition)
• Fuel pressure stays consistent at 39 RPM's under load
• Pulled the boat out and checked for damaged props and debris
• Trim tabs and Drive Trim are working as intended
• Throttle and shift cables are 2yrs old
• Verified throttle position reading matches controls

At the request of the dealer, I uploaded a YouTube video with both engines plugged into a diagnostic laptop and fuel pressure gauge. I also noted a few data points in excel

A few things I've noticed

• the spark advance on Starboard never goes above 26 degrees
• I've seen Port jump to 32 degrees

Any ideas? This issue is driving me nuts!

Thank you!

 

[hughespat57]

For what its worth I’m a former ASE Master technician so this isn’t idle opinions.

You have the advantage of twins so I would start with swapping the ECMs.
Pretty easy and see if the issue moves over. It could be a bad one or miss programmed if the advance is different

Look at all the values MAP, crank sensor, knock sensor these can affect advance curve

 

[MrKulio]

For what its worth I’m a former ASE Master technician so this isn’t idle opinions.

You have the advantage of twins so I would start with swapping the ECMs.
Pretty easy and see if the issue moves over. It could be a bad one or miss programmed if the advance is different

Look at all the values MAP, crank sensor, knock sensor these can affect advance curve

Thanks! Havent thought of that! I will try this tomorrow and report back.

 

[hughespat57]

Looking at your numbers
After ecm swap I would swap map sensor and look for any vacum leaks

assume a compression check was done while plugs out?

 

[MrKulio]

Looking at your numbers
After ecm swap I would swap map sensor and look for any vacum leaks

assume a compression check was done while plugs out?

I will try that as well when i swap ECMs. And no, no compression test has been done. Need to rent or buy a tester this weekend.

 

[Bill Curtis]

I don't see engine temp on the chart. That can effect timing and fuel, also.

 

[hughespat57]

To Bill’s point the ecm will use all the sensors to determine fuel and timing

So check the harness and all sensors are plugged in fully and nothing got broken during the installation

 

[MrKulio]

I don't see engine temp on the chart. That can effect timing and fuel, also.

In the video, you can see the temps never exceed 161. It’s also what i thought might be initially, but definitely not it.

i will check all the other sensors today. Thanks Bill!

 

[MrKulio]

Swapped the ECM and MAP sensors. No luck!

would the crank sensor be worth replacing?

 

[Bill Curtis]

How about the Mass Air Flow Sensor and the Air Inlet temp sensor

 

[hughespat57]

@MrKulio
Let's step back and look at the overall again for a minute.
Would these be a fair statements, correct any with specifics if you disagree...
Starboard engine can make WOT of 4800 (eventually)?
Starboard engine seems to have less power during mid-range (vs Port)?

FYI
160F is the normal thermostat for a raw water (saltwater) cooled engine.

 

[MrKulio]

@MrKulio
Let's step back and look at the overall again for a minute.
Would these be a fair statements, correct any with specifics if you disagree...
Starboard engine can make WOT of 4800 (eventually)?
Starboard engine seems to have less power during mid-range (vs Port)?

FYI
160F is the normal thermostat for a raw water (saltwater) cooled engine.

starboard has no power after 2500 rpm. If i give it any more throttle, there is zero response and the engine sound doesnt change. While port will scream and roar all the way up to 3200 rpm and continue to climb beyond that once on plane. Once on plane, starboard’s RPMs will go up slowly with a maximum of 3800 rpm vs port 4800-5000 rpm.

 

[scoflaw]

could be in rpm reduction mode. Not sure about your ecm but know there is a 10 and a 90% setting

 

[MrKulio]

could be in rpm reduction mode. Not sure about your ecm but know there is a 10 and a 90% setting

thought that might be it too, but had it hooked up to my laptop while under load (see my video). Available power stays at 100%. Also tried swapping the ECMs yesterday. Same issue

 

[MrKulio]

One interesting note from yesterday’s test run…I noticed a slight vibration coming from Starboard while it was at idle. Was almost a rhythmic vibration. Could a misaligned engine or an issue with the drive yoke/spline cause loss of power?

ill check the torque on the engine mounts and transom plate bolts today.

 

[hughespat57]

@MrKulio
I know this is very frustrating for you having just gone thru a lot of work and a lot of money.
The basic rule of any diagnostics is each test needs to prove or disprove something specific.
Swapping the ECM is easy and it proves the issue is not the ECM. Or the issue would have swapped with it.
Did you get to do the compression check? Having a basic mechanical issue is never going to be solved by the engine controls. You need a baseline, I understand it should be fine, but you need to know its fine.

Looking again at your numbers and the video.
At the 3500 readings.
Port Starboard
32% 56% throttle
10.8 14.9 fuel flow
10.06 13.48 manifold psi
(the closer to ambient psi 14.3 the less vacuum that engine is pulling because that throttle is open wider)
Fuel flow is a calculated number, the ECM knows the fuel rail pressure and how long it is opening each injector, it knows the injectors can flow x fuel based on those values. So it's pumping more fuel into the Starboard.

So the computers think the Starboard engine is under a large load
While the Port is doing less work

Can the Port hit 5000RPM? If it can look at the numbers and see if rev limiting is keeping it from exceeding 5000.

Could you be chasing the wrong engine?
Could the clutch in the Port be slipping and the Starboard is doing to much work?
Or one of the port prop hubs is slipping?

 

[MrKulio]

@MrKulio
I know this is very frustrating for you having just gone thru a lot of work and a lot of money.
The basic rule of any diagnostics is each test needs to prove or disprove something specific.
Swapping the ECM is easy and it proves the issue is not the ECM. Or the issue would have swapped with it.
Did you get to do the compression check? Having a basic mechanical issue is never going to be solved by the engine controls. You need a baseline, I understand it should be fine, but you need to know its fine.

Looking again at your numbers and the video.
At the 3500 readings.
Port Starboard
32% 56% throttle
10.8 14.9 fuel flow
10.06 13.48 manifold psi
(the closer to ambient psi 14.3 the less vacuum that engine is pulling because that throttle is open wider)
Fuel flow is a calculated number, the ECM knows the fuel rail pressure and how long it is opening each injector, it knows the injectors can flow x fuel based on those values. So it's pumping more fuel into the Starboard.

So the computers think the Starboard engine is under a large load
While the Port is doing less work

Can the Port hit 5000RPM? If it can look at the numbers and see if rev limiting is keeping it from exceeding 5000.

Could you be chasing the wrong engine?
Could the clutch in the Port be slipping and the Starboard is doing to much work?
Or one of the port prop hubs is slipping?

Port is definitely running as intended. On a clear day last week, i pushed each engine on its own and you can feel Port can almost get the boat on plane on its own. Feels very powerful. When i try and run the boat with just starboard, it feels weak. No power after 2400-2500 rpm.

 

[hughespat57]

Ok,
The numbers indicate at the same RPM the Starboard is using 45% more fuel at a wider throttle, yet not turning that into HP.
If those numbers are true then either an injector is clogged/bad and not opening at all, or that fuel is just running thru a dead cylinder.

I really would do a compression check.
You could swap the TPS fairly easy.
If that's all good then unplug one injector at a time, this should throw a code, but you should hear/feel the engine change if that cylinder was getting fuel and firing. When done clear all the codes. You could also pull the plug wires one at a time which ever is easier.

 

[mrsrobinson]

Asking the obvious question and maybe it's already been asked or stated, why are you doing all this work versus the shop that installed the new engines?

 

[MrKulio]

Asking the obvious question and maybe it's already been asked or stated, why are you doing all this work versus the shop that installed the new engines?

installed the engines myself along with my buddy who is a certified marine mechanic. He did most of the troubleshooting and finally told me to work with the engine dealer on the rest. He is booked solid for the remainder of the season and has helped as much as he could.