Carb vs EFI?

[ChiliPepperGarage]

I previously posted about tuning the carb for altitude of my jetbote. It came from an elevation of under 700 feet and I'm over 5000 feet. Did some research and got the jets and metering rods needed for my elevation and am going to play with it today (Edelbrock 750).

I will be doing most of my boating at my local lake but next summer I know I'm going to want to make trips to the Delta which is much lower in elevation. I'm going to document my current timing and bag the jets and rods so I can switch back to the lower elevation setting for the Delta trips but pulling the carb and re-tuning every time sounds like kind of a pain. I though maybe I'd just buy a second carb and then just switch carbs for those trips.

Then I got thinking about going with an FITech or Holley Sniper injection. I can just plug in a computer and do a quick retune. I've never run either on a car or a boat so was wondering if any of you have done so and what were your results. Is it easier to tune? Did you get better performance? Was it worth the money?

I know a second carb is cheaper than the EFI but if performance increases it might be worth it. On the other hand, I'm a big proponent of keeping things simple and analog. I also have 3 Holley 750 carbs (2 new, 1 used but very good condition) that I could use. They are electric choke, vacuum secondary automotive carbs. I don't know how they would work in a marine application but if they would, then they would be a good solution to carb swap when needed.

Also, my boating goals are reliability and ease of boating. I don't mind playing with my cars in my shop but for boating, I just want to be able to launch, relax and have fun without messing with it. I don't need to go 90 MPH either, 60 would be fine.

 

[renodaytona]

I'd swap the Edelbrock out for the Holley.

If you have wet exhaust EFI can become a pain having to run O2 sensors and not burn them up. There are a couple threads on here of guys doing the Holley EFI but I think are still dealing with some issues.

One guy that we ran with up here had an LS powered jet boat (dry headers) with the Holley system it ran great but lost a bearing and toasted the motor.

 

[coolchange]

I’m not a fan of edelbrock. That said I could do a jet change in 5 minutes and not spill a drop of fuel.
Thousands of dollars for a perceived benefit, that probably won’t be easy.
If it runs good now, fuck with it until it doesn’t.

 

[Gelcoater]

I previously posted about tuning the carb for altitude of my jetbote. It came from an elevation of under 700 feet and I'm over 5000 feet. Did some research and got the jets and metering rods needed for my elevation and am going to play with it today (Edelbrock 750).

I will be doing most of my boating at my local lake but next summer I know I'm going to want to make trips to the Delta which is much lower in elevation. I'm going to document my current timing and bag the jets and rods so I can switch back to the lower elevation setting for the Delta trips but pulling the carb and re-tuning every time sounds like kind of a pain. I though maybe I'd just buy a second carb and then just switch carbs for those trips.

Then I got thinking about going with an FITech or Holley Sniper injection. I can just plug in a computer and do a quick retune. I've never run either on a car or a boat so was wondering if any of you have done so and what were your results. Is it easier to tune? Did you get better performance? Was it worth the money?

I know a second carb is cheaper than the EFI but if performance increases it might be worth it. On the other hand, I'm a big proponent of keeping things simple and analog. I also have 3 Holley 750 carbs (2 new, 1 used but very good condition) that I could use. They are electric choke, vacuum secondary automotive carbs. I don't know how they would work in a marine application but if they would, then they would be a good solution to carb swap when needed.

Also, my boating goals are reliability and ease of boating. I don't mind playing with my cars in my shop but for boating, I just want to be able to launch, relax and have fun without messing with it. I don't need to go 90 MPH either, 60 would be fine.

A carb swap for both locations sounds easier than an EFI swap to me?
And cheaper especially if you already have the carbs.
Look into getting the vent tubes that go back into the carb opening and any other marine specific parts.

At the end of the day, should the time not be perfect I think I’d rather have screws and jets to mess with vs trying to see a computer screen.
But then? Computers frustrate the shit out of me, so

 

[Racey]

Avoid the sniper system. I'd say avoid Holley efi all together for a multitude of reasons, but that's another issue altogether.

You should be fine just doing a jet swap and carb adjustment, it's not that difficult.

The bulk of the cost of EFI is NOT the computer, which is why i can never understand buying 'bargain' computers.

You will have a bunch of money wrapped up in hose, fittings, pump, regulator, sensors, injectors, throttle, crank trigger, coils, harness, etc, etc, etc.

It will easily turn into a several thousand dollar project. So unless you are ready to bite that bullet, the carb ain't bad.

Personally i'd switch to the Holley Carb over the Edelbrock, but either will work.

 

[ChiliPepperGarage]

So sounds like I should just try one of my Holley's first and see how it runs. I have a Holley jet kit and lots of Holley parts and am more familiar with them.

The thing about the Edelbrock is you have to pull the top of the carb off to get to the jets. The benefit of that is no gaskets below the gas level so no potential leaks. The down side is you have to take apart the top of the carb and there are 8 screws that can fall into the carb and intake so I have to remove the carb off the motor to be safe. Again, for simplicity sake, I'd rather just have two carbs and swap them out. Very easy and quick to do if both carbs are identical. And I have the 3 Holley's but only the one Edelbrock. The down side of the Holley's are they are automotive so I'd want to convert them to marine (not sure what that entails but will figure it out. How hard can it be?) and then tune one for 5K feet which should be easy to do here but then tune the other for lower elevation which means I'd have to try to tune it down at that elevation.

 

[Blackmagic94]

I’ve had great results with Holley sniper on two engines so far. They now have a sniper 2 that has improvements that just came out.

 

[CommanderLee]

Like what was mentioned above the O2 sensor is the issue with wet exhaust. I have several buddies at one of the large aftermarket fuel injection companies and have talked to them about doing the switch many times and the issue always is the O2 sensor. There are ways to tune it and then lock it out but now you are losing the benefits of computer controlled fuel injection. Plus you can usually fix a carb on the water at least enough to get you back to the ramp. I have basically an entire Holley rebuild kit in a ziploc bag on the boat.

 

[gottaminute?]

So sounds like I should just try one of my Holley's first and see how it runs. I have a Holley jet kit and lots of Holley parts and am more familiar with them.

The thing about the Edelbrock is you have to pull the top of the carb off to get to the jets. The benefit of that is no gaskets below the gas level so no potential leaks. The down side is you have to take apart the top of the carb and there are 8 screws that can fall into the carb and intake so I have to remove the carb off the motor to be safe. Again, for simplicity sake, I'd rather just have two carbs and swap them out. Very easy and quick to do if both carbs are identical. And I have the 3 Holley's but only the one Edelbrock. The down side of the Holley's are they are automotive so I'd want to convert them to marine (not sure what that entails but will figure it out. How hard can it be?) and then tune one for 5K feet which should be easy to do here but then tune the other for lower elevation which means I'd have to try to tune it down at that elevation.

i would look real close at the combination of sizes between the jets and metering rods. you MAY be able to juggle the two parts so that two screws and swapping metering rods only will get you "close enough" to be happy at both elevations. an idle mixture adjustment at the same time will clean that up and takes no parts.

just my 2 pieces of copper plated zinc expressed as an opinion.

 

[Racey]

So sounds like I should just try one of my Holley's first and see how it runs. I have a Holley jet kit and lots of Holley parts and am more familiar with them.

The thing about the Edelbrock is you have to pull the top of the carb off to get to the jets. The benefit of that is no gaskets below the gas level so no potential leaks. The down side is you have to take apart the top of the carb and there are 8 screws that can fall into the carb and intake so I have to remove the carb off the motor to be safe. Again, for simplicity sake, I'd rather just have two carbs and swap them out. Very easy and quick to do if both carbs are identical. And I have the 3 Holley's but only the one Edelbrock. The down side of the Holley's are they are automotive so I'd want to convert them to marine (not sure what that entails but will figure it out. How hard can it be?) and then tune one for 5K feet which should be easy to do here but then tune the other for lower elevation which means I'd have to try to tune it down at that elevation.

I wonder if anyone makes an o-ring sealed spacer. That would make the carb swap super nice and easy.

 

[Racey]

Like what was mentioned above the O2 sensor is the issue with wet exhaust. I have several buddies at one of the large aftermarket fuel injection companies and have talked to them about doing the switch many times and the issue always is the O2 sensor. There are ways to tune it and then lock it out but now you are losing the benefits of computer controlled fuel injection. Plus you can usually fix a carb on the water at least enough to get you back to the ramp. I have basically an entire Holley rebuild kit in a ziploc bag on the boat.

That is 100% not true. You still have all the benefits of fuel injection in open loop mode (locked out as you say).

In fact every single high performance engine i have ever dealt with, or ones we've setup are open loop. The ECU is TUNED CORRECTLY, there is no need for o2 feedback for anything other than logging. For example If you have an injector failure, the o2 sensor won't save you, as it will just richen up the other cylinders that don't need fuel. Or take fuel out if an injector is stuck open, you just turned a 1 cylinder problem into an 8 cylinder problem. If you have a fuel pressure issue, that is compensated for in a good ECU's fuel molar mass calcs. If you have fuel aeration, o2 will not save you there either as it will hit cylinders randomly and inconsistently

At the most closed loop control should be limited to a very narrow margin only to account for some variable you have been unable to simulate or correctly model. (Like a very cold day, or very high altitude that you didn't go test at), and should be clamped at maybe 5%, mayyyybe 10% control.

Closed loop control is crazy as you are putting 100% faith into a single $200 sensor as a failure point, and a sensor that has a high failure rate to boot.


A lot of guys leave the closed loop on because they have been too lazy to properly do an in depth tune on the engine, so they just rely on it. It's absolutely crazy in my opinion. I would never trust closed loop to that extent.

 

[CommanderLee]

That is 100% not true. You still have all the benefits of fuel injection in open loop mode (locked out as you say).

In fact every single high performance engine i have ever dealt with, or ones we've setup are open loop. The ECU is TUNED CORRECTLY, there is no need for o2 feedback for anything other than logging. For example If you have an injector failure, the o2 sensor won't save you, as it will just richen up the other cylinders that don't need fuel. Or take fuel out if an injector is stuck open, you just turned a 1 cylinder problem into an 8 cylinder problem. If you have a fuel pressure issue, that is compensated for in a good ECU's fuel molar mass calcs. If you have fuel aeration, o2 will not save you there either as it will hit cylinders randomly and inconsistently

At the most closed loop control should be limited to a very narrow margin only to account for some variable you have been unable to simulate or correctly model. (Like a very cold day, or very high altitude that you didn't go test at), and should be clamped at maybe 5%, mayyyybe 10% control.

Closed loop control is crazy as you are putting 100% faith into a single $200 sensor as a failure point, and a sensor that has a high failure rate to boot.


A lot of guys leave the closed loop on because they have been too lazy to properly do an in depth tune on the engine, so they just rely on it. It's absolutely crazy in my opinion. I would never trust closed loop to that extent.

But would it work with the change in elevations that the OP was asking about? Not trying to start an argument just wanting to educate myself. Also the company I was referring to, this was being discussed with one of their designers so maybe it was a limitation of their system. Once they said it wasn't the best idea, the last time we spoke about it the conversation changed directions. Plus I am positive alcohol was involved as it always is when we are on the road together working shows.

 

[rivermobster]

Holly for one altitude and an Edelbrock for the other.

That way you don't get em confused.

 

[Bigbore500r]

The obvious answer here is...

DUAL QUADS WITH A FUEL SELECTOR !

Just select which carb your feeding fuel to depending on altitude

 

[rivermobster]

The obvious answer here is...

DUAL QUADS WITH A FUEL SELECTOR !

Just select which carb your feeding fuel to depending on altitude

Fake tunnel ram for the win.

 

[Bigbore500r]

Fake tunnel ram for the win.

Run a mullet setup.......
Small carb in the front, big carb in the back!

PARTY!

 

[77charger]

Properly tuned carb should be able to go from sea level to 5000 ft easily. I’ve had a couple older carbed trucks as a young adult I’d go from parents house in laguna niguel to big bear do some trails in them mtns then come home.

Sure it wasn’t as peppy as the flat lands but it wasn’t fogging mosquitos either. I’ve also taken boat to big bear years ago same deal. Now if I used 90 percent at elevation I’d jet for main use.

 

[77charger]

Avoid the sniper system. I'd say avoid Holley efi all together for a multitude of reasons, but that's another issue altogether.

You should be fine just doing a jet swap and carb adjustment, it's not that difficult.

The bulk of the cost of EFI is NOT the computer, which is why i can never understand buying 'bargain' computers.

You will have a bunch of money wrapped up in hose, fittings, pump, regulator, sensors, injectors, throttle, crank trigger, coils, harness, etc, etc, etc.

It will easily turn into a several thousand dollar project. So unless you are ready to bite that bullet, the carb ain't bad.

Personally i'd switch to the Holley Carb over the Edelbrock, but either will work.

Wanted to go this route too but after thinking the real cost my carb is fine. Have a Weber afb on it now. Might swap to a Holley since easier to tune and more familiar with them.

 

[gottaminute?]

The obvious answer here is...

DUAL QUADS WITH A FUEL SELECTOR !

Just select which carb your feeding fuel to depending on altitude

not really that far off.... many tuners will do a different tune for different parameters and store them in the ecu allowing the user to toggle between them. street tune/ track tune. low boost/ high boost. pump gas in 1 tank/ race gas in the other. low boost pump gas/ high boost race gas. different fixed fuel and ignition curves for each scenario. endle$$ po$$ibilties.

 

[Blackmagic94]

From how I got it. To when I added 6-71 and new 750s that I setup up for boost. To Holley super sniper efi


Efi is 10000x better than the other setups and faster. I even tuned the carbs with a wideband and I still picked up 8 mph on efi

 

[v6toy4x]

I like the edelbrocks myself, easy to work on, on the motor, nothing comes apart below fuel level and the metering rods.

Of course it has been "a while" since I had either Holey or Edelbrock in my hands, I have gone to the dark side (EFI)

 

[DaveH]

But would it work with the change in elevations that the OP was asking about? Not trying to start an argument just wanting to educate myself. Also the company I was referring to, this was being discussed with one of their designers so maybe it was a limitation of their system. Once they said it wasn't the best idea, the last time we spoke about it the conversation changed directions. Plus I am positive alcohol was involved as it always is when we are on the road together working shows.

systems that halve barometric pressure sensors handle this very nicely.

 

[coolchange]

From how I got it. To when I added 6-71 and new 750s that I setup up for boost. To Holley super sniper efi


Efi is 10000x better than the other setups and faster. I even tuned the carbs with a wideband and I still picked up 8 mph on efi View attachment 1278208 View attachment 1278209 View attachment 1278210

If you’re picking up 8 mph over carbs in a wot situation your carbs are fucked up.

 

[Eliminator21vdrive]

KISS

 

[Blackmagic94]

If you’re picking up 8 mph over carbs in a wot situation your carbs are fucked up.

The efi has higher cfm than the carbs did.

 

[Racey]

The efi has higher cfm than the carbs did.

That's not the fault of the carb though, you just needed a bigger carb

 

[Racey]

But would it work with the change in elevations that the OP was asking about? Not trying to start an argument just wanting to educate myself. Also the company I was referring to, this was being discussed with one of their designers so maybe it was a limitation of their system. Once they said it wasn't the best idea, the last time we spoke about it the conversation changed directions. Plus I am positive alcohol was involved as it always is when we are on the road together working shows.

Systems that use MAP (Manifold Absolute Pressure) as their primary load source (most systems) do a decent job of dealing with this, as under wide open throttle you see lower Manifold Pressure at higher altitude, so you work in that area of the map for your fueling.

Systems that use MAP over BAP (Barometric Absolute Pressure) do an even better job as you can account for exhaust characteristic of the exhaust not fighting as high of outside pressure to resist it's flow.

 

[thetub]

wonder if AI can become a factor n EFI closed loop or tuning ?

 

[LargeOrangeFont]

wonder if AI can become a factor n EFI closed loop or tuning ?

Its not AI but that capability exists. Many systems will self “toon” to get you in the ballpark. It is only as good as the data you give it though. It’s not gonna self toon to perfection.

 

[DarkHorseRacing]

wonder if AI can become a factor n EFI closed loop or tuning ?

I don’t think AI is really necessary since you’re talking about sensor readings and how the ECU can adjust to those readings. It’s more a straight math problem than intuition.

If your asking if AI could compensate for a failed injector, no, but if you want to, you just put EGT sensors on every collector pipe coming out of the exhaust and that would be able to detect a “dead cylinder”. Then it’s just a matter of what program kicks in on that detection. Immediate limp mode probably.

 

[Blackmagic94]

That's not the fault of the carb though, you just needed a bigger carb

Well we went from 1400 to 1600 cfm total airflow.


Also the carbs never ran the afr as constant as efi does hence better tuning and mo powa. I’m sure someone could tune the carbs better then I did but I was able to make the efi leagues better. The carbs would do stupid shit like back fire on snap closed throttles and sometimes stall which is scary as hell when you chop throttle at 70 mph on decel


And I agree. Wideband feedback should never exceed 10% and should be temp limited as well.

 

[Racey]

Its not AI but that capability exists. Many systems will self “toon” to get you in the ballpark. It is only as good as the data you give it though. It’s not gonna self toon to perfection.

Exactly. there is absolutely no such thing as "Self Tuning"

If you rely on the advertised "self tuning" features, you are asking for expensive lessons.

 

[thetub]

Its not AI but that capability exists. Many systems will self “toon” to get you in the ballpark. It is only as good as the data you give it though. It’s not gonna self toon to perfection.

listen here know it all learn to spell toon before commenting understand me

 

[Racey]

I don’t think AI is really necessary since you’re talking about sensor readings and how the ECU can adjust to those readings. It’s more a straight math problem than intuition.

If your asking if AI could compensate for a failed injector, no, but if you want to, you just put EGT sensors on every collector pipe coming out of the exhaust and that would be able to detect a “dead cylinder”. Then it’s just a matter of what program kicks in on that detection. Immediate limp mode probably.

These are the features that separate the men from the boys in the EFI world.

It's all about the software. Some are the disney land autobahn, very narrow and rigid functionality. Others are a wide open sandbox where literally the only limit is your ability to design and implement the functions you can dream up.

 

[n2otoofast4u]

EFI sucks.

 

[kurtis500]

Id run a Quickfuel or Holley. I had the full $5000+ holley MPFI system on a 468 LS6. Computer adjusted distributor, knock sensors and every sensor you could put on it. I took it off after about 4 years and sold it. I loved it but in a 21ft Howard v-drive cruiser it was too many problems. I carried extra O2 sensors on the boat incase one got taken out. It can be done with purpose made equipment but id stick with the carb. The modern EFI engines for boats are made for the environment. Converting the older ones creates a lot of headaches on the water. Especially if your runing exhausts near the water. Even when the motor is shut off the steam runs up and takes out the sensor. Most of my failures were after it ran great and was parked, when I came out an hour or so later to run it again the sensor was bad. I had the sensor moved 3 times and the sxhausts specially welded to accomodate. Cars have mufflers/converters etc. between the open air and the sensor, a boat doesnt. A system like mine is best in closed loop and very tuneable. Open loop is better for water. When it ran great it was perfect, it was the other 10% of the time that made it not worth it. My .02

 

[LargeOrangeFont]

listen here know it all learn to spell toon before commenting understand me

Can we toon up yore punctuation?

 

[coolchange]

I like the edelbrocks myself, easy to work on, on the motor, nothing comes apart below fuel level and the metering rods.

Of course it has been "a while" since I had either Holey or Edelbrock in my hands, I have gone to the dark side (EFI)

Click. Metering rods. Hell if you got it set up right you wouldn’t even have to take the top of the carb off. Just change the rod.
Or just lower the rods a notch lol.

 

[SBMech]

TBI injection is nothing like Port EFI. A modern system with any forced induction setup will be lightyears ahead of any carburation. It's not even close.

Problem is that the cost of a stand alone sequential injection setup like Mercury Racing uses that provides those control points necessary to make top power are very expensive. A MoTec controller setup with full sequential ignition/fuel/wastegate controls would be in the 5 figures range, nothing if you are installing it on a 100k offshore motor, a ton if you are playing around with the average 8-10k performance marine engine.

Those scary things Racey mentioned about the dumb TBI systems installed are true, unless you are using port sequential type of controls with the ability to sense misfires due to ignition/fuel faults you are running blind.

But in all honesty, a well tuned carb is not leaving much on the table comparatively as far as performance unless we're talking into the 1000+hp ranges.

 

[shan]

Racey makes many good points. If you can't tune a carburetor you have no business trying to tune EFI. Fueling 8 cylinders based on O2 from a bank of four can be problematic for reasons he mentioned. I think in many cases EFI gets a bad name due to poor wiring practices. All of the sensors are very low current circuits, meaning if there is added resistance the sensor output will be wrong. At the end of the day, carburetor or EFI, if you don't know what you're doing you better pay someone that does. My $.02. Edit: I don't know shit about Edelbrock (Carter) carburetors. I've always used Holleys.

 

[DaveH]

wonder if AI can become a factor n EFI closed loop or tuning ?

Huh? You must mean that MOST aftermarket systems cannot "self tune".

It's a system. It has parameters for the pressures/signals/controls and types of components installed. It's all based upon how much power/type of fuel/use.

Systems built for racing are best at 3/4 to full throttle/output because that is where it spends the majority of it's time and what it's tuned around. Fuel pressures, how much fuel flow, type of ignition and induction, compression and typical use are the targets to build around. Once it's built within said specifications, then the "tuning" begins.

Automotive systems are "self tuning" because of design and parameters such as having to meet certain emissions levels, communicate on a public platform/interface (OBD2) they mostly worry about drivability and emissions. They also only have around 15% total fuel control, the main 10% or so controlled by the air measurement device(s) MAF/HotFilm/MAP with reference to a barometer (usually on the mainboard). The 02 sensors can drive about 5% of it.

They can "self tune" because all the parameters are known, fuel pressure, injector size, expected cam curve, compression ect is all plugged in allready.

Racing automotive systems are designed to make as much power without blowing up the engine while lasting at maximum output for as long as possible. They take into account the cam grind, timing, ignition systems used, compression ratio, blown or turbo'd etc to form a base build. They can be dumb like a TBI system that basically replaces the carb , to full blown sequential injection and ignition with COP and complete control over the firing event by using cam/crank sensor type systems that count incrementally teeth of an installed timing gear on the cams and many systems use the flywheel/ring gear for double duty for this job on the crank end.

Point being EFI is the way to go, if you understand it, and can budget for it. The systems that are "tuned" for open circuit running cannot self tune because they are not designed to nor do they have the tools to continually fine-tune the mixture, considering they lack several points of input usually like 02 feedback, and lack of cam/crank measurement for ignition and injector control.

self tuning is nothing more then marketing BS to help sell EFI hardware to users that are ambivalent about their tuning skills.

so lets be real here.....EXACTLY what is self tuning? the ONLY functionality i have ever seen is a target air/fuel table that the ECU tries to achieve via 100% pure faith in the 02 sensor measurement. i have never seen any self tune system that does anything other then that, and a proper tune is a lot more then just desired target fuel ratios.

furthermore, and this is where most people get into trouble with auto-tune, is the fact that the 02 sensor is often highly inaccurate, in fact given all the sensors modern ECU utilize, the 02 is the least accurate of any of them, but for some stupid reason people believe the measurement that is received as spot on. under many operating conditions of the enigne....it isnt even CLOSE. This is especially true in marine engines berceuse of the exhausts system. So even if you have a function 02 system, lumpy cams, short runner exhaust and so forth introduce huge inaccuracies that need to be sniffed out by the tuner, not the ECU closed loop system.

 

[motormonkey]

I just marinized a edelbrock afv2. Works great in this mild setup. Very smooth and the annular primaries make a big difference at idle and in no wake zones. So easy.

 

[mattyc]

I wonder if anyone makes an o-ring sealed spacer. That would make the carb swap super nice and easy.

That would be slick, I'll bet @Racey could make you a nice one

 

[Blackmagic94]

self tuning is nothing more then marketing BS to help sell EFI hardware to users that are ambivalent about their tuning skills.

so lets be real here.....EXACTLY what is self tuning? the ONLY functionality i have ever seen is a target air/fuel table that the ECU tries to achieve via 100% pure faith in the 02 sensor measurement. i have never seen any self tune system that does anything other then that, and a proper tune is a lot more then just desired target fuel ratios.

furthermore, and this is where most people get into trouble with auto-tune, is the fact that the 02 sensor is often highly inaccurate, in fact given all the sensors modern ECU utilize, the 02 is the least accurate of any of them, but for some stupid reason people believe the measurement that is received as spot on. under many operating conditions of the enigne....it isnt even CLOSE. This is especially true in marine engines berceuse of the exhausts system. So even if you have a function 02 system, lumpy cams, short runner exhaust and so forth introduce huge inaccuracies that need to be sniffed out by the tuner, not the ECU closed loop system.

Auto tuning afr is nice for light load driving and idle to speed the process up. It’s also great once the tune is set to adjust for climate and altitude adjustments that you know, fuck with carbs.

 

[Sharp Shooter]

I don't know shit about Edelbrock (Carter) carburetors. I've always used Holleys.

Have you seen their latest?

 

[Racey]

Auto tuning afr is nice for light load driving and idle to speed the process up. It’s also great once the tune is set to adjust for climate and altitude adjustments that you know, fuck with carbs.

I've never found it to be worth a shit for idle as that is where the o2 sensor gets the most distorted readings from tailpipe reversion.

Stable idle with the highest vacuum attainable (tightest closed throttle you can make work) Then use timing control for primary stall prevention and desired idle speed, IAC for additional help. closed loop fuel at idle leads to a hunt and seek, and even if sometimes the idle may actually seem stable, if you look at the fueling it's hunting all over the place on pulse width rich then lean continually.

Usually will never give any closed loop fueling until after 2500 RPM

 

[LargeOrangeFont]

Auto tuning afr is nice for light load driving and idle to speed the process up. It’s also great once the tune is set to adjust for climate and altitude adjustments that you know, fuck with carbs.

If the thing is tuned right.. that what the sensors in an EFI system are for. There should be no “tuning adjustments” needed for temp and altitude if it is tuned correctly.

 

[LargeOrangeFont]

I've never found it to be worth a shit for idle as that is where the o2 sensor gets the most distorted readings from tailpipe reversion.

Stable idle with the highest vacuum attainable (tightest closed throttle you can make work) Then use timing control for primary stall prevention and desired idle speed, IAC for additional help. closed loop fuel at idle leads to a hunt and seek, and even if sometimes the idle may actually seem stable, if you look at the fueling it's hunting all over the place on pulse width rich then lean continually.

Usually will never give any closed loop fueling until after 2500 RPM

Spot on.

I have my car tuned speed density, full open loop. The only sensors on the thing are MAP, TPS, intake temp and coolant temp. It runs perfect at any altitude in any temp.

 

[DaveH]

I've never found it to be worth a shit for idle as that is where the o2 sensor gets the most distorted readings from tailpipe reversion.

Stable idle with the highest vacuum attainable (tightest closed throttle you can make work) Then use timing control for primary stall prevention and desired idle speed, IAC for additional help. closed loop fuel at idle leads to a hunt and seek, and even if sometimes the idle may actually seem stable, if you look at the fueling it's hunting all over the place on pulse width rich then lean continually.

Usually will never give any closed loop fueling until after 2500 RPM

and this is what separates the bargain ECU from the GOOD ECU's.

 

[shan]

Have you seen their latest?

View attachment 1279666

I did see that.