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Mefi 1 rev limiter.

Headless hula

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Is mefiburn the only way to raise the rev limit on a mefi 1 ecu? Are there any other options? (Without sending it to someone.)
Thanks!
 

Racey

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There are other software than MEFIBurn, but if the rev limiter is part of the ECU and not the ignition system (like an MSD) then your only option is getting into the software of the computer.

MEFIBurn has just become the most common one....


Also if you are running a MEFI 1 on something that has been built enough to raise the rev limiter you probably ought to consider upgrading the ECM, MEFI 1's are extremely limited in their tuning. I haven't been inside one in years, but if i remember correctly it's almost all 2D tables, so very limited in mid range tuning.
 

Headless hula

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There are other software than MEFIBurn, but if the rev limiter is part of the ECU and not the ignition system (like an MSD) then your only option is getting into the software of the computer.

MEFIBurn has just become the most common one....

I have stock mercruiser ignition.
Stock mercruiser ecu.
Motor isn't stock....
I'd like to bump the rev to 5600-5800.
Motor is built to handle 6000.

Seems the rest of the calibration is good. I know it's rich, but it runs really good throughout the range. Starts at all temps really good.
Just want to bump up the limiter.
 

Racey

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I have stock mercruiser ignition.
Stock mercruiser ecu.
Motor isn't stock....
I'd like to bump the rev to 5600-5800.
Motor is built to handle 6000.

Seems the rest of the calibration is good. I know it's rich, but it runs really good throughout the range. Starts at all temps really good.
Just want to bump up the limiter.

So you never re-tuned the ecu and your non-stock motor is running on a stock cal?......

How "non-stock" is the motor?

Seems good, and is actually good are two different things :p

If you make changes to the airflow components of the motor, and motor is making more power etc, you should be at least going through the tune to verify on O2 that your mixtures are correct across all normal operating conditions.

The same person that does this can also bump your rev limiter for you....
 

Headless hula

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So you never re-tuned the ecu and your non-stock motor is running on a stock cal?......

How "non-stock" is the motor?

Seems good, and is actually good are two different things :p

If you make changes to the airflow components of the motor, and motor is making more power etc, you should be at least going through the tune to verify on O2 that your mixtures are correct across all normal operating conditions.

The same person that does this can also bump your rev limiter for you....

I have the guy that can tune it. Just looking for alternatives to mefiburn.
 

Headless hula

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Just got off the phone with Bob @ mefiburn.
I'll hopefully have it by Saturday.

Schweet!
 

Trash

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There are other software than MEFIBurn, but if the rev limiter is part of the ECU and not the ignition system (like an MSD) then your only option is getting into the software of the computer.

MEFIBurn has just become the most common one....


Also if you are running a MEFI 1 on something that has been built enough to raise the rev limiter you probably ought to consider upgrading the ECM, MEFI 1's are extremely limited in their tuning. I haven't been inside one in years, but if i remember correctly it's almost all 2D tables, so very limited in mid range tuning.

Its a table in the MEFI 1.

His MEFI 1 will work fine with that motor. I've got the same motor modified slightly more and the MEFI 1 works great. The simpleness actually makes it somewhat easier. The tables for fuel and spark are 3D. Fidelity is only an issue for certain rpm/map break points depending on the prop and none of those issues are show stoppers or performance degraders.

I would NOT waste the time and money for a new harness and MEFI as the cost and performance benefit would be ZERO.
 

Racey

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Its a table in the MEFI 1.

His MEFI 1 will work fine with that motor. I've got the same motor modified slightly more and the MEFI 1 works great. The simpleness actually makes it somewhat easier. The tables for fuel and spark are 3D. Fidelity is only an issue for certain rpm/map break points depending on the prop and none of those issues are show stoppers or performance degraders.

I would NOT waste the time and money for a new harness and MEFI as the cost and performance benefit would be ZERO.

Yep, i just opened my old laptop and saw that, No fuel control above 5200, and no Spark control over 3600, but not really a problem for a basic marine engine in most cases in regards to the spark. and no provisions for positive manifold pressure (boost). MEFI 3 was fully 2D boost control, so very limited tuning in boost areas, that's where i remember the 2D tuning from. Super brave doing across the board compensations for manifold pressure. :p

Untitled.jpg

Here is the extent of both the fuel (left) and spark (right) tables in MEFI 1


EDIT:

Just for any bystanders reading the thread, here are just the fuel tables in a MEFI 4 for comparison

Untitled2.jpg

They split them into 4 separate tables in MEFI 4, (this is not including the 2 additional tables for 1000-9000 RPM for 0-7.5psi of boost, and 7.5-15psi) But you can see how much more tunability there, this is especially important in transitional areas, right off idle, and into the mid range. And this is still a nearly 20 year old system, things are much more advanced in modern systems.
 

Enen

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What's your opinion on the MEFI 4 vs other options. I'm reading from your post that MEFI 4 is more advanced and tunable than the previous MEFI's. How does it stack up against a MoTec, or EFI Technologies that Carson uses, or AEM that Alexi works with for example?
 

Trash

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Yep, i just opened my old laptop and saw that, No fuel control above 5200, and no Spark control over 3600, but not really a problem for a basic marine engine in most cases in regards to the spark. and no provisions for positive manifold pressure (boost). MEFI 3 was fully 2D boost control, so very limited tuning in boost areas, that's where i remember the 2D tuning from. Super brave doing across the board compensations for manifold pressure. :p

View attachment 509003

Here is the extent of both the fuel (left) and spark (right) tables in MEFI 1


EDIT:

Just for any bystanders reading the thread, here are just the fuel tables in a MEFI 4 for comparison

View attachment 509004


They split them into 4 separate tables in MEFI 4, (this is not including the 2 additional tables for 1000-9000 RPM for 0-7.5psi of boost, and 7.5-15psi) But you can see how much more tunability there, this is especially important in transitional areas, right off idle, and into the mid range. And this is still a nearly 20 year old system, things are much more advanced in modern systems.

Racey I don't debate there is more fidelity with the later MEFI ECMs and would NOT use a MEFI 1 for any boost application. The reality is he would see zero performance increase and ease of tunability switching MEFIs. A MEFI 1 loads in about 3 -5 seconds. Its over 2 minutes for a MEFI 3. With the later MEFIs you have to pay particular attention to table overlap as noted by the table headers.

The timing stopping at 3600 rpm is somewhat false. The F1 slope extension table accounts for timing beyond that and in nearly all cases you don't need to touch timing above that for this type of application. It is significantly better than a fixed ignition curve.

Fuel above 5200 is not a factor for this application either. VE typically starts to depress and thus no further fueling is typically required. I've talked with others that have spun big blocks to over 6000 rpm with a MEFI 1 and no fuel issues. I've personally gone to 5700 rpm with a stable 12.5 AFR from 4800 to 5700.

Having tabular values for 200-500 rpm and anything less than 40 kPa is zero value added for a tuner. Motors don't run at 200-500 rpm. Anything less than 40Kpa is virtual vacuum no load, snap idle decel parameters. In other words the same BPW for 2000 rpm and 40 kPa will work fine for 30 kPa. No need to duplicate the value.

IF someone was starting from scratch and needed an EFI ECM I would not suggest a MEFI 1,2 or 3, and likely not a 4 only because the Holley systems are better. However, if one had an existing MEFI unit, I would keep it and tune away.
 

Headless hula

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Looking forward to adding this phase to my build thread for sure! Thank you guys for the assistance!
 

Trash

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Headless,

It would be very interesting to get wide band data off your current configuration with mods and a stock tune. After running wide band for 6 years I can't imagine running without it.

Keep us posted and looking forward to updates.
 

Racey

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Racey I don't debate there is more fidelity with the later MEFI ECMs and would NOT use a MEFI 1 for any boost application. The reality is he would see zero performance increase and ease of tunability switching MEFIs. A MEFI 1 loads in about 3 -5 seconds. Its over 2 minutes for a MEFI 3. With the later MEFIs you have to pay particular attention to table overlap as noted by the table headers.

The timing stopping at 3600 rpm is somewhat false. The F1 slope extension table accounts for timing beyond that and in nearly all cases you don't need to touch timing above that for this type of application. It is significantly better than a fixed ignition curve.

Fuel above 5200 is not a factor for this application either. VE typically starts to depress and thus no further fueling is typically required. I've talked with others that have spun big blocks to over 6000 rpm with a MEFI 1 and no fuel issues. I've personally gone to 5700 rpm with a stable 12.5 AFR from 4800 to 5700.

Having tabular values for 200-500 rpm and anything less than 40 kPa is zero value added for a tuner. Motors don't run at 200-500 rpm. Anything less than 40Kpa is virtual vacuum no load, snap idle decel parameters. In other words the same BPW for 2000 rpm and 40 kPa will work fine for 30 kPa. No need to duplicate the value.

IF someone was starting from scratch and needed an EFI ECM I would not suggest a MEFI 1,2 or 3, and likely not a 4 only because the Holley systems are better. However, if one had an existing MEFI unit, I would keep it and tune away.

Read my post, i'm not stating in peak HP performance at all, and i wasn't knocking anything he had nor saying he should change any of it, i was simply putting it out there so that anyone coming across the thread could see the difference visually that we are talking about. I specifically stated that in most basic marine applications timing control beyond 3600 isn't really needed as you've already reached your peak timing by then, A regular distributor is works the same way and gets the job done for MOST applications, including this one.... Fuel control over 5200 in this application would actually most likely mean the curve going leaner at the top as the motor most likely mild and has gone beyond it's peak torque, so worse case is the motor runs richer than it ought to beyond 5200, and probably only for a 500rpm band (at a 5700 redline) that won't be seen extensively for the running life of the engine anyway.

I have spent plenty of time tuning all different kinds of systems, Marine, Offroad, Street Car, Track Car (Drag and Circuit), Motorcycle, Etc. Marine engines are very forgiving because single gear, single load curve. MEFI 1 would not work well in a car because of these limitations in it's table breakpoints, but it was never designed to be used in one in the first place so that's a moot point. He will be fine, i was simply posting information so that anyone that came across this that has never actually seen inside what we are discussing could have a visual to help them understand. :thumbsup

Carburetors were fine for nearly 70 years before someone came up with something better as well ;) :p
 

Headless hula

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i was simply posting information so that anyone that came across this that has never actually seen inside what we are discussing could have a visual to help them understand. :thumbsup

Carburetors were fine for nearly 70 years before someone came up with something better as well ;) :p[/QUOTE]



Which is exactly why I started this thread. I want other to be able to find some useful knowledge if they decide to take a similar path. There is so little information available that is easy to figure out for a "newb".

Trash, as always I find your posts very informative and helpful.
Racey, thanks to you for weighing in, as I'm aware of your vast knowledge on the subject as well.

I hope you guys have a great holiday weekend and are able to enjoy the water with family and friends.
I know I will!
 

Headless hula

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Headless,

It would be very interesting to get wide band data off your current configuration with mods and a stock tune. After running wide band for 6 years I can't imagine running without it.

Keep us posted and looking forward to updates.



I'll be getting a o2 bung welded into my riser next week if all goes well. Any suggestions on brand?
 

Racey

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I'll be getting a o2 bung welded into my riser next week if all goes well. Any suggestions on brand?

Summit and jegs both sell them, make sure you get a stainless one, i prefer the ones with a hex nut rather than an allen as the allen is not as strong and these things usually end up getting tight over time. Also put some GOOD anti-sieze on the threads when you put the plug in. :thumbsup
 

Headless hula

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Summit and jegs both sell them, make sure you get a stainless one, i prefer the ones with a hex nut rather than an allen as the allen is not as strong and these things usually end up getting tight over time. Also put some GOOD anti-sieze on the threads when you put the plug in. :thumbsup

How about brand of afr gauge?
 

Racey

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How about brand of afr gauge?

If someone is gonna tune the boat for you, have them use their own, If you want your own, i think the innovative one is what most guys buy that don't want to drop big money on the super high end ones.

The ones we have from Australia are like $2,000 for the controller and the sensors alone are around $250 themselves..... So obviously not practical for a DIY'r from a cost perspective, the Innovative one is around $400 i think and that may include the sensor.

Also being marine and with the load changes slow and subtle you don't need the super wazoo high end one. The expensive ones have much more rapid response times, this is helpful when you are looking at fraction of a second o2 changes under throttle snaps, corner exits on race cars for example, really trying to dial in your acceleration enrichments to not waste fuel. Doesn't apply to the boat world so need to drop that kind of money.


Edit: AEM may also sell one, and they have good products as well that don't break the bank :thumbsup Like everything costs have come down on the sensors and controllers greatly over the years, and quality/performance has gone up, so even the cheaper ones today are actually pretty damn good for most applications.

Edit2 : The NTK Uego is the good sensor type in use today, so you want a controller that works with that sensor :thumbsup
 

Headless hula

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In reality, I'll be able to tune in the boat as well as on a dyno. I'm very fortunate to have a good friend who does this for a living. He did not have the software for the mefi control, so that's why I pursued it.

Thanks man!
 

Headless hula

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Just took off a mefi3 off of my 575sci if interested Don't really know what they are worth

It depends on what all you are parting with.
If it includes the manifold and the harness, it can get some pretty decent $$.
I think it depends on the time of year too.
 

22tunnel

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I have both TBI's and mounting plate with 575sci harness
 
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