Mercruiser 4.5l low vacuum, WOT 4350 and higher fuel consumption

[damo79]

Once again, when you are done with your thesis, let us know. The rest of us would have replaced it all by now. Stop wasting our time.

Sorry you feel it that way. I appreciate all your input tried my best to reply and took your advises. "Replaced it all" - did you mean battery what @muc advised or TMAP again what you recommend. As mentioned is new and also verified against gauge.

 

[damo79]

Have you ever been part of a boat test for a magazine? I have, and I sure wouldn't use what they published as a substitute for actual testing.
The people who do these are trying to sell boat --- plain and simple. I've read the article (that's how I found out it takes 3-4 months from the test to published) about the test I was part of. They "bend" the numbers to make things look a "little" better.

I'll just be up front with you. I'm not here because I don't know how to fix this boat. I spent over 30 years as the guy people like you brought the boat to when they couldn't fix it themselves. You are here because you can't fix it yourself.

Your troubleshooting skills are weak.
Your reasoning seems flawed to me.
The testing you have done so far is incomplete.
The opinions you have are based some things you read on the internet --- but only when they agreed with your preconceived ideas.

"Does this drop affect issue with low vacuum which in your opinion doesn't exist - sorry but don't think so."
I don't care what you think, I don't care about a 555 table you found.
I work with facts not speculation.

Low vacuum is only a symptom, not a cause. And yes at this point I don't believe you have low vacuum.

I don't understand why you want to argue with the advise I'm trying to give you. If you want me to, I'll stop posting.

But, I will still try my best to help you.
Fix the voltage issue.
Fix the sea water pressure problem and while you're doing that, if you pull the drive -- count how many times the prop shaft spins when you turn the drive shaft 10 complete revolutions. Or if your just dropping the lower, buy a new o-ring for the top cap and count the teeth.
Try to get a good REC file.

I'm not trying to argue - sorry if it looks that way. I just have my opinion and want to say it, and hoped this forum is the place for it.
I will fix all the things you mentioned and get back. Don't worry you will hear what was the outcome of that story. Maybe it's nothing wrong with it and I'm just chasing my tail.

 

[damo79]

@muc and because you think that vacuum pressure is not too low can you please tell us what is the correct range? Hope with your experience you have access to this kind of information?

 

[tpenfield]

I am traveling home today and should be able to give those Diacom file a look later in the day.

 

[alldodge]

Once again, when you are done with your thesis, let us know. The rest of us would have replaced it all by now. Stop wasting our time.

Sir, this kind of posting will not be tolerated.

 

[tpenfield]

@damo79 . . . I took a quick look at the files, and will look more in the AM. One question . . .

the files tend to show the TPS1/2 and arbitrated TPS maxing out briefly, but then come down. Are you reducing the throttle or is the engine deciding to do that itself?

If you can / need to, make a file of the boat / engine warmed up and then brought to WOT for a while (20-30 seconds) and then back to idle.

Just a hunch at this point, but more information about WOT would help clarify things for me. (sorry if this is covered in the posts already)

The recording did not show any fault codes, but I am wondering if you are getting a guardian mode warning?

 

[nola mike]

@damo79 . . . I took a quick look at the files, and will look more in the AM. One question . . .

the files tend to show the TPS1/2 and arbitrated TPS maxing out briefly, but then come down. Are you reducing the throttle or is the engine deciding to do that itself?

If you can / need to, make a file of the boat / engine warmed up and then brought to WOT for a while (20-30 seconds) and then back to idle.

Just a hunch at this point, but more information about WOT would help clarify things for me. (sorry if this is covered in the posts already)

Yeah, I had wanted that earlier. Also mentioned on the static images that timing was reduced at higher rpm, wanted to see if there was info on why buried in there. Feeling left out now not being able to see the diacom files. I might see if I can get it to run on a Windows VM...

 

[muc]

@damo79 . . . I took a quick look at the files, and will look more in the AM. One question . . .

the files tend to show the TPS1/2 and arbitrated TPS maxing out briefly, but then come down. Are you reducing the throttle or is the engine deciding to do that itself?

If you can / need to, make a file of the boat / engine warmed up and then brought to WOT for a while (20-30 seconds) and then back to idle.

Just a hunch at this point, but more information about WOT would help clarify things for me. (sorry if this is covered in the posts already)

The recording did not show any fault codes, but I am wondering if you are getting a guardian mode warning?

Hey Ted, Are you using the graph function to see these numbers?

 

[muc]

@muc and because you think that vacuum pressure is not too low can you please tell us what is the correct range? Hope with your experience you have access to this kind of information?

No I can't, sorry. I understand your desire to see some published MAP numbers from MerCruiser --- I would to, but they don't that I can find.

What I can find is numbers from engines that are similar to yours ----- but all of these engines have cats your engine doesn't have cats.

The trouble with finding an engine like yours (4.5 MCM 250hp non cat) installed in a USA boat will be very hard. Don't quote me on this because I'm going for memory. For a non cat engine to be installed in a USA boat, that boat would have to be a 2010 or older hull and been certified by MerCruiser to the EPA. To make this worse, these next gen engines from MCM came out during a time Mercury had realized there was a lot more money to be made selling (O/Bs) outboards then there ever would be selling I/Os. O/Bs cost slightly more upfront, cost roughly 3X in repairs over their life span and have a somewhat shorter life span. In salt water O/Bs might make sense --- I have spent my career in Minnesota, so I really don't know much about salt water boating. I'm talking about anything over 200hp because your can't buy an I/O under that. Just a guess, but there are probably less then 50 engines like yours ever made.

What I can give your are numbers that Mercury published for a 250hp, 4.6L engine with PCM112 controller, with O2 sensors and no cats, but basically the same ignition and fuel system. Yup, it's an O/B with 8 cylinders and overhead cams driving 4 valves per cylinder.
MAP @ idle = 5-7 psi -- that pretty much equals 9.7-14.4 inHg
MAP @ WOT is within 15% of baro

So no I don't "think" you have low vacuum. But I don't have "drop dead" numbers to back that up. And I'm not sure you will ever find those numbers.

What I do think you have is an overloaded engine. this could be caused by a number of things. A couple of those many things that might cause this.
1. Propping, this can be wrong prop, wrong gear ratio, excessive friction due to engine misalignment or bad hull.
2. Warn out or damaged engine resulting in reduced power output.

Does your Diacom have something like "cylinder balance test" or "cylinder canceling" or mays "cylinder drop test"? This will make sure all 6 cylinders have roughly the same amount of power. Might be a good test for you to run. If it has that function let me know and I can give you advise on how to run it. It is a quick and east test --- but easy to do wrong.

 

[tpenfield]

@damo79 . . . I took a quick look at the files, and will look more in the AM. One question . . .

the files tend to show the TPS1/2 and arbitrated TPS maxing out briefly, but then come down. Are you reducing the throttle or is the engine deciding to do that itself?

If you can / need to, make a file of the boat / engine warmed up and then brought to WOT for a while (20-30 seconds) and then back to idle.

Just a hunch at this point, but more information about WOT would help clarify things for me. (sorry if this is covered in the posts already)

Hey Ted, Are you using the graph function to see these numbers?

yes

 

[damo79]

@damo79 . . . I took a quick look at the files, and will look more in the AM. One question . . .

the files tend to show the TPS1/2 and arbitrated TPS maxing out briefly, but then come down. Are you reducing the throttle or is the engine deciding to do that itself?

If you can / need to, make a file of the boat / engine warmed up and then brought to WOT for a while (20-30 seconds) and then back to idle.

Just a hunch at this point, but more information about WOT would help clarify things for me. (sorry if this is covered in the posts already)

The recording did not show any fault codes, but I am wondering if you are getting a guardian mode warning?

What I see TPS1/2 only max out during acceleration when the boat is getting on plane. You can see it on first attached screenshot (that's from 1st Daicom recording i sent you).
The same you can see from second recording. Its pretty much what you asked for but 15sec at WOT. TPS1/2 max out only while getting on plane and then acceleration from 4000-WOT it only goes up from 450 to 650. PCM must be doing it. Strange that at WOT it reduces throttle opening to 65%. Thanks - never noticed that and thanks for your time. Should the throttle be wide open at WOT?

 

[tpenfield]

Just trying to catch up on this thread . . . sorry but I have not read through every post . . .

Back story is . . .

• New to the OP boat/engine, prior performance numbers unknown (?)
• 2016 Engine, has some sort of warranty history and then offered out in 2018.
• Engine won't go over 4,350 RPM
• Raw water cooled, does not appear to be an EC model

Will the engine maintain 4350 (ish) RPM (?) Not sure if that has been stated/verified. In the engine graphs, I am not sure if the OP is backing off the throttle. As @muc stated it would be good to see a test run with RPM increased in 500 RPM increments for a minute or so, until the throttles are at WOT.

Is there a boat speed associated with the 4350-4400 RPM?

Can 'we' go down a notch in the prop pitch to see if the engine will reach 4800-5200 WOT range?

 

[damo79]

No I can't, sorry. I understand your desire to see some published MAP numbers from MerCruiser --- I would to, but they don't that I can find.

What I can find is numbers from engines that are similar to yours ----- but all of these engines have cats your engine doesn't have cats.

The trouble with finding an engine like yours (4.5 MCM 250hp non cat) installed in a USA boat will be very hard. Don't quote me on this because I'm going for memory. For a non cat engine to be installed in a USA boat, that boat would have to be a 2010 or older hull and been certified by MerCruiser to the EPA. To make this worse, these next gen engines from MCM came out during a time Mercury had realized there was a lot more money to be made selling (O/Bs) outboards then there ever would be selling I/Os. O/Bs cost slightly more upfront, cost roughly 3X in repairs over their life span and have a somewhat shorter life span. In salt water O/Bs might make sense --- I have spent my career in Minnesota, so I really don't know much about salt water boating. I'm talking about anything over 200hp because your can't buy an I/O under that. Just a guess, but there are probably less then 50 engines like yours ever made.

What I can give your are numbers that Mercury published for a 250hp, 4.6L engine with PCM112 controller, with O2 sensors and no cats, but basically the same ignition and fuel system. Yup, it's an O/B with 8 cylinders and overhead cams driving 4 valves per cylinder.
MAP @ idle = 5-7 psi -- that pretty much equals 9.7-14.4 inHg
MAP @ WOT is within 15% of baro

So no I don't "think" you have low vacuum. But I don't have "drop dead" numbers to back that up. And I'm not sure you will ever find those numbers.

What I do think you have is an overloaded engine. this could be caused by a number of things. A couple of those many things that might cause this.
1. Propping, this can be wrong prop, wrong gear ratio, excessive friction due to engine misalignment or bad hull.
2. Warn out or damaged engine resulting in reduced power output.

Does your Diacom have something like "cylinder balance test" or "cylinder canceling" or mays "cylinder drop test"? This will make sure all 6 cylinders have roughly the same amount of power. Might be a good test for you to run. If it has that function let me know and I can give you advise on how to run it. It is a quick and east test --- but easy to do wrong.

Thanks for information. Now I can understand why you don't agree with my "guessing" with vacuum. Think we can call it that way as we dont really know what it should be.
I would probably gave up with this but there's only one but. Fuel pressure - can we agree that what manual says is correct? 41-45psi at idle and 52psi with reference line disconnected. I do get 52psi at idle with vacuum hose disconnected. If we agree on that I can do one simple test. Connect the pressure gauge to fuel line, second one to FSM vaccum line with T to the vacuum pump and see what kind vacuum will give me 41-45psi pressure.
9.7-14.4" you mentioned won't give me that range if at 13" fuel pressure it's already at 46psi. I know what you gonna say - cheap gauges, can't rely on that.

I thought about engine being overloaded as well hat's why prop was replaced. Outrdive checks were on my list after season until I found vacuum "only" 13". I will check it all anyway.
I will check test options in Diacom but from what I remember very little was highlighted there. Not sure if that's Diacom or PCM limitation.

 

[damo79]

Just trying to catch up on this thread . . . sorry but I have not read through every post . . .

Back story is . . .

• New to the OP boat/engine, prior performance numbers unknown (?)
• 2016 Engine, has some sort of warranty history and then offered out in 2018.
• Engine won't go over 4,350 RPM
• Raw water cooled, does not appear to be an EC model

Will the engine maintain 4350 (ish) RPM (?) Not sure if that has been stated/verified. In the engine graphs, I am not sure if the OP is backing off the throttle. As @muc stated it would be good to see a test run with RPM increased in 500 RPM increments for a minute or so, until the throttles are at WOT.

Is there a boat speed associated with the 4350-4400 RPM?

Can 'we' go down a notch in the prop pitch to see if the engine will reach 4800-5200 WOT range?

All back story is correct. You can see on latest recording that it went over 4500rpm but it was me playing with trim until prop started ventilating. It does keep max rev anyway.

I can give you speed vs rpm later on.

Prop pitch was already dropped from 21 to 19" to standard setup for VR5 with 1.62 gear ratio. RPM changed by maybe 150rpm. Surely I can continue with dropping the pitch until I get 5200 but thw boat will be probably still underperformed. I can understand that if it wasn't standard package, changed engine, fitting to different boat etc.

 

[tpenfield]

A couple things I noticed so far . . . Not saying those are the issues, but . . .

TPS at idle is 4% . . . Seems high, but maybe it is normal for the 4.5L

Engine is reaching 4500 RPM as per the later run on August 4th.

Still wanting to see a run in throttle increments to see where things fall apart. (if they are falling apart)

Do we know the current prop pitch? (19P . . . I would try a 17P for kicks & giggles)

Was this boat tested/trialed before acquiring it?

 

[tpenfield]

The range for WOT RPM is 4800-5200, so 5,000 is a good target.

Are we at altitude? MIL sitting in the back?

 

[tpenfield]

I have a bunch of runs on my 6.2L which is the bigger brother of the 4.5L, so I can cross-check some of the data from a behavioral aspect.

 

[tpenfield]

Also the throttle body is a single field replace-able unit (pricey), but it has an internal actuator (motor) that actually opens the throttle per the Arb. TPS value. I am wondering if the full movement of the throttle plate can be / has been verified (ignition on, engine not running, throttle at WOT position)?

 

[damo79]

I have a bunch of runs on my 6.2L which is the bigger brother of the 4.5L, so I can cross-check some of the data from a behavioral aspect.

Bigger brother same family, mercruiser own design?

 

[damo79]

A couple things I noticed so far . . . Not saying those are the issues, but . . .

TPS at idle is 4% . . . Seems high, but maybe it is normal for the 4.5L

Engine is reaching 4500 RPM as per the later run on August 4th.

Still wanting to see a run in throttle increments to see where things fall apart. (if they are falling apart)

Do we know the current prop pitch? (19P . . . I would try a 17P for kicks & giggles)

Was this boat tested/trialed before acquiring it?

That 4500 is prop ventilation as I sad before. With optimal trim its probably max 4400.

Current prop is 14.5x19 SS

No tests before I got the boat.