Mercruiser mpi ecu mapping

QBhoy

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Guys. Don’t give me a hard time here…asked this previously I’m sure…but is anyone any further forward in mapping or bypassing the ecu in these ? I’m perhaps recently made aware that perhaps whipple have a license to do this ? Is there any other alternative? Has anyone managed to ditch the 555 and go stand alone mapping ?
Asking because my particular boat was made as a special performance edition back early 2000’s. In their wisdom it had a performance cam thrown in her…but mapping left as it was. Resulting in very poor low down ability, but a powerhouse up top, with perhaps a risk of being lean ? Literally can hear her over fuelling or even overlapping. Throws fuel out the side exhausts at idle.
she’s incredibly quick top end with some pitch on the prop…but at her best top end, she will be at her worst low down. So always have to run much less pitch to make her useable for planing or cruising with weight. Sounds very different from any other v8 short block I’ve heard, as a result. It’s nothing nothing…then everything when she gets to late 3000’s or into the 4000’s.
Any help from over there appreciated !
 

achris

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What's the engine? (cereal number etc... the whole 9 yards)
 

QBhoy

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What's the engine? (cereal number etc... the whole 9 yards)
I’ve the serial number somewhere. It’s a 2003 5.0 mpi 260 that they threw a cam into without a thought to what would happen. Get the number when I look it out
 

achris

More fish than mountain goat
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Yeah, 260hp from a 5L for a boat is just stupid! You're 'benefiting' from the demand for more power and less cubes (and people mistakenly thinking less cubes = less fuel. More on that at the end), and finding out firsthand what I'm on about all the time.

As far as re-mapping goes, yes, I remember Whipple being authorised. I think there is another company doing it too.... I've just had a look at the camshaft. It's the same as used for ages. So maybe the mapping is causing your 'peakiness'... But I can't see any different ECU for a 5.0L engine. It appears they are all the same... Maybe you have a different problem? Maybe a leaking injector, hence the richness and poor performance at lower speeds. Higher speeds may be enough to keep pace with the leak and 'hide' it. I'd be looking at everything else before doing a remap. Fuel rail pressure, injectors spray pattern and volume, timing and advance curve performance... Even to the point of checking the correct plugs are in and the leads and firing order are correct...

So, on to my fuel use story...
Vehicle 1.. 2018 Nissan Navara. Completely standard. Engine 2.5L I4 turbo diesel. Kerb mass 2060kg.
Vehicle 2. 2010 Mazda BT-50. Also completely standard. Engine 3.0L I4 turbo diesel. Kerb mass 1900kg.
Vehicle 3. 1999 Toyota Landcrusier. Heavily modified (roo bar, dual battery, winch, towbar, uprated but not 'lifted' suspension). Engine 6.5L V8 Turbo diesel. Kerb weight 2600kg.

Guess the fuel consumptions...

Vehicle 1 - city driving - 13.5L/100km
Vehicle 2 - 1000km highway drive - 12.4L/100km (Perth to Laverton)
Vehicle 3 - city driving - 11.8L/100km

All vehicles driven by the same person!

So the next person who tells me a small engine will use less fuel is going to get told! (again!) ;)

Chris.........
 

achris

More fish than mountain goat
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Unless you're saying it's a cam that was put in by someone 'after the fact', and not the standard Mercruiser cam. In that case, I don't think anything but a return to a standard Mercruiser cam will sort you out. Sorry.
 

nola mike

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So, a heavier car with a bigger engine *in the city* gets better mileage than a smaller engine in a lighter weight car on the highway? Sorry, not buying it...
 

QBhoy

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Unless you're saying it's a cam that was put in by someone 'after the fact', and not the standard Mercruiser cam. In that case, I don't think anything but a return to a standard Mercruiser cam will sort you out. Sorry.
Yeah. That’s the deal. Performance can thrown in it.
good story above too !
 

achris

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So, a heavier car with a bigger engine *in the city* gets better mileage than a smaller engine in a lighter weight car on the highway? Sorry, not buying it...
I'm sorry you feel that way. I was the driver of all 3 cars, and those figures are genuine, and over long periods, not just one-offs.

BTW, the facts don't care if you 'buy it' or not... (just ask Neil Degrasse Tyson :))

Chris......
 

Lou C

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It’s a lot more complex than just weight and displacement. Torque curve, gear ratios and spacing between ratios to name a few. BTW our 07 Jeep 5.7 liters 5 spd auto and 98 Jeep 4.0 liter 4 speed auto get nearly the same fuel economy and the 07 weighs 700 lbs more….
 

Scott06

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Yeah. That’s the deal. Performance can thrown in it.
good story above too !
Yeah put the standard marine 5.0 cam or relatively equivalent marine cam , if you need more power swap in a 5.7 or 383 longblock and remap that .
 

alldodge

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Being a 2000 its probably a MEFI, and being a MEFI means anyone can retune with software like MEFIBURN
 

QBhoy

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Yeah put the standard marine 5.0 cam or relatively equivalent marine cam , if you need more power swap in a 5.7 or 383 longblock and remap that .
It’s more power low down I could do with. It’s pretty potent further up. Open to more power everywhere though, haha. Been on the hunt for good used a 6.2 mpi for years. But never found one as nice as the engine I have is.
 

Scott06

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It’s more power low down I could do with. It’s pretty potent further up. Open to more power everywhere though, haha. Been on the hunt for good used a 6.2 mpi for years. But never found one as nice as the engine I have is.
Yeah feel the same way. I repowered 21 ft BR from a 4.3 to a 5.0, should have just stepped over the 5.0 and done a 5.7…. Biggest engine offered in my boat was a 5.0 mpi, thought a 5.7 would be too much, have yet to own a boat with too much power ….
 

achris

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Been on the hunt for good used a 6.2 mpi for years. But never found one as nice as the engine I have is.
Good luck finding anything like that in Scotland.. Like trying to find a good secondhand NON-MARINE 4.3 in Australia...
 
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