ECM Swap ? Plug and play ???

apw30534

Seaman
Joined
Jan 14, 2022
Messages
55
Thinking about doing some upgrades/mods to my 2007 8.1 Gi-H... one of which (recommended by Larry Hofer at Raylar) is to swap out the 375hp Gi ECM for the 420hp GX-i ECM.

I found a part number for the correct unit (3889007) but do not know for sure if it is a plug-n-play situation... or if it will need to be flashed/programmed by a VP dealer.

Anyone have an answer to this ?

Thanks in advance !
 
Last edited:

alldodge

Supreme Mariner
Joined
Mar 8, 2009
Messages
37,046
From my looking around its my "opinion" this will do nothing to give you more power, or maybe noticeable power.

Your original ECM 3885461 is NLA and not finding the replacement just looking at your motor

In other discussions finding 3885461, 3885465 is replaced by 3889007

When a boat manufacture sells a boat the motor is rated at the prop. When just a motor is bought it can be rated at the flywheel. Most reductions are normally between 25 to 30 HP. Your motor list 375HP and the newer list 420HP, being a 45HP difference.

The newer ECM probably does produce more HP, but just how much more actual HP is the difference I'm discussing. Other un-researched variables would be, are there any other sensor changes (MAP, TPS, Temp, etc) which allows for the increase in HP is unknown

Maybe @muc can add thoughts
 

apw30534

Seaman
Joined
Jan 14, 2022
Messages
55
From my looking around its my "opinion" this will do nothing to give you more power, or maybe noticeable power.

Your original ECM 3885461 is NLA and not finding the replacement just looking at your motor

In other discussions finding 3885461, 3885465 is replaced by 3889007

When a boat manufacture sells a boat the motor is rated at the prop. When just a motor is bought it can be rated at the flywheel. Most reductions are normally between 25 to 30 HP. Your motor list 375HP and the newer list 420HP, being a 45HP difference.

The newer ECM probably does produce more HP, but just how much more actual HP is the difference I'm discussing. Other un-researched variables would be, are there any other sensor changes (MAP, TPS, Temp, etc) which allows for the increase in HP is unknown

Maybe @muc can add thoughts
One difference I can confirm is the camshaft. The Gi and GXi have different part numbers.
Larry Hofer at Raylar specifically said to look for the 420hp ECM because it will work with his 520hp heads/cam package.
I am not expecting "more power" from the ECM swap... I am trying to prepare for these additional Raylar upgrades during the off-season.
I believe the main difference between the two ECM's is more aggressive ignition timing and higher rev limiter... but according to the parts diagrams... the ECM is definitely different from the Gi to the GXi.

My current ECM is part# 3817805, which does cross reference to a 8.1Gi-H:
The GXi-G is the 420hp version of my engine... which takes the 3889007 ECM.
 

Attachments

  • 20220914_172410.jpg
    20220914_172410.jpg
    422.8 KB · Views: 3

muc

"Retired" Association of Marine Technicians...
Joined
Jul 7, 2004
Messages
1,845
Thinking about doing some upgrades/mods to my 2007 8.1 Gi-H... one of which (recommended by Larry Hofer at Raylar) is to swap out the 375hp Gi ECM for the 420hp GX-i ECM.

I found a part number for the correct unit (3889007) but do not know for sure if it is a plug-n-play situation... or if it will need to be flashed/programmed by a VP dealer.

Anyone have an answer to this ?

Thanks in advance !
I’ve been retired for a few years so my information is a bit outdated. But back then if I needed a ECM, I would order by serial number. I wasn’t allowed to order a high output ECM for a standard engine. The only people who could load a program was Volvo or their dealer support tech, he carried a few ECMs that he could load for testing purposes. He also would update ECMs for us when needed. So if you buy a used ECM with that part number it should come with the program associated with that P/N. That’s why 2 ECMs that Have exactly the same components will have 2 different P/Ns, it’s the program that makes the difference.
The last couple of factory classes I attended started teaching us how to update and reflash ECMs. But this was only for dealers that had Volvos software Vodia installed on our laptop. And it was on a case by case basis making it impossible to reflash a standard engine to a high output engine.
What happens now is that when Vodia is connected to an engine it looks at the installed software package and checks to see if it’s correct and has the latest update. Then alerts us if we need to do anything.

If you’re buying into Raylar you should follow his instructions. From what I understand he has engineered packages.

Here is what I learned about standard vs high output. When we would discuss this in class we were told that sometimes the only difference was the ECM program, sometimes it would also include other components like cam, throttle body, exhaust and heads to name a few.
The Marina I worked for did a very good job of test driving the different boats to determine the best engines to install based on performance vs cost. We only ordered the HO engines when it made a big enough difference to justify the price. But we did have a few customers that would special order boats that went against our recommendation. What I found was that the boats that benefited the most from the HO engines were the ones that got a lower pitched prop set to take advantage of the higher rev limit. The ones that ran the same pitch props, not so much.

Almost no dealer will modify a engine that was designed to meet an emissions standard, we are told that it’s not worth the possible problems.

Just got a service bulletin from Mercury a few days ago. They are starting to encrypt the ECMs. I don’t think they were going to say anything but problems started coming up with multiple engine boats. The engines need to “talk” to each other and if they aren’t all the same it causes issues. The fix is to encrypt the unencrypted ECM.

Good luck with your project, some hulls (not many) can benefit from more power. Hence rule 3


Rules I’ve learned from the boat business.
#1 no cash- no splash
#2 never buy a saltwater boat thinking you’re getting a “deal”
#3 if you want a faster boat- buy a faster boat, it’s usually cheaper than trying to make yours faster
 

apw30534

Seaman
Joined
Jan 14, 2022
Messages
55
I’ve been retired for a few years so my information is a bit outdated. But back then if I needed a ECM, I would order by serial number. I wasn’t allowed to order a high output ECM for a standard engine. The only people who could load a program was Volvo or their dealer support tech, he carried a few ECMs that he could load for testing purposes. He also would update ECMs for us when needed. So if you buy a used ECM with that part number it should come with the program associated with that P/N. That’s why 2 ECMs that Have exactly the same components will have 2 different P/Ns, it’s the program that makes the difference.
The last couple of factory classes I attended started teaching us how to update and reflash ECMs. But this was only for dealers that had Volvos software Vodia installed on our laptop. And it was on a case by case basis making it impossible to reflash a standard engine to a high output engine.
What happens now is that when Vodia is connected to an engine it looks at the installed software package and checks to see if it’s correct and has the latest update. Then alerts us if we need to do anything.

If you’re buying into Raylar you should follow his instructions. From what I understand he has engineered packages.

Here is what I learned about standard vs high output. When we would discuss this in class we were told that sometimes the only difference was the ECM program, sometimes it would also include other components like cam, throttle body, exhaust and heads to name a few.
The Marina I worked for did a very good job of test driving the different boats to determine the best engines to install based on performance vs cost. We only ordered the HO engines when it made a big enough difference to justify the price. But we did have a few customers that would special order boats that went against our recommendation. What I found was that the boats that benefited the most from the HO engines were the ones that got a lower pitched prop set to take advantage of the higher rev limit. The ones that ran the same pitch props, not so much.

Almost no dealer will modify a engine that was designed to meet an emissions standard, we are told that it’s not worth the possible problems.

Just got a service bulletin from Mercury a few days ago. They are starting to encrypt the ECMs. I don’t think they were going to say anything but problems started coming up with multiple engine boats. The engines need to “talk” to each other and if they aren’t all the same it causes issues. The fix is to encrypt the unencrypted ECM.

Good luck with your project, some hulls (not many) can benefit from more power. Hence rule 3


Rules I’ve learned from the boat business.
#1 no cash- no splash
#2 never buy a saltwater boat thinking you’re getting a “deal”
#3 if you want a faster boat- buy a faster boat, it’s usually cheaper than trying to make yours faster
Thanks so much for the detailed reply. Super helpful.
I see Vodia software on ebay. I wonder if this is pirated/hacked stuff that will let me into the ECM.
I did something similar with Toyota Techstream and was able to access dealer level stuff.

I will keep my eyes out for the GXi ECM. Its probably the cheapest/easiest upgrade and suggested by Larry Hofer. He also mentioned Holley EFI... which i would consider if it didnt involve hacking up my wire harness.
The boat is currently pristine so I want to make all mods appear factory stock.
The bump from the 375hp Gi to a Raylar 525hp kit should be a fun, noticable and affordable upgrade.
Very much looking forward to it.
 
Top