Author Topic: The difference between closed loop & open loop fuel maps?  (Read 5366 times)

Offline MLR

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The difference between closed loop & open loop fuel maps?
« on: June 17, 2014, 07:53:15 PM »
I've been doing a fair amount of reading about using GuzziDiag to upload & download different fuel maps and have a few questions you guys might be able to help with. Is a closed loop fuel map "static", meaning it will not change due to outside environmental conditions such as temperature & barometric pressure? If this is the case is a fuel map running with the Lambdas off closed? I'm assuming the reason for turning the Lambdas off is to make the fuel map more tunable? I just want to understand this a bit more clearly before I make any changes to the stock map. In the spring and fall the temperature can change by as much as 30degreesF from when I leave in the morning and when I come home. I also thought it might it be a bad idea to be running a fuel map with the Lambdas off if I was to take a trip with a lot of elevation changes?

I am new to the Guzzi scene, just bought a 2012 Norge last April and really love it. WildGuzzi is awesome and I greatly appreciate all the time and effort that has been put into it.

Thanks!

Matt

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Re: The difference between closed loop & open loop fuel maps?
« Reply #1 on: June 17, 2014, 08:24:25 PM »
Here's what I understand about modern EFI systems, particularly the ones on our motorcycles:

There are lots of inputs to the basic ECU map.  You have barometric pressure, ambient air temp, engine oil temp, rpm, throttle position, phase of the moon, etc.  Each of these creates a + or - to the base map.  Our lambdas (O2 sensors) are narrow band...they are setup to tell the ECU that the gas mix is too rich or too lean, not how much but just that the ECU needs to make changes to bring the gas mix back to the target ratio.  No matter what you do, the lambdas will be trying to get the mix back to a very lean condition.  You can alter the map for the rpm range that is closed loop but then you are 'fighting' the lambda signal to the ECU.  In other words, if you richen up the map  for closed loop rpms the lambdas will indicate 'too rich' and tell the ECU to go leaner, exactly what you do not want.  Deleting the O2 sensors takes you back to the base map, albeit with all the other modifiers.  I'll argue that a good base map, with input for pressure, air temp, engine oil temp, and rpm is all you need.  No need for all the other add on crap on the market...if the base map is a good one.

To answer your basic question, guzzidiag will give you a base map that is still subject to some adjustment by the various sensors on your bike.

On my Stelvio 8V I have the lambdas deleted.  The bike runs great!

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Re: Re: The difference between closed loop & open loop fuel maps?
« Reply #2 on: June 17, 2014, 09:29:49 PM »
Closed loop is, by definition, less static, because it takes the open loop map and adjusts it for real time O2 sensor feedback. And does so to lean it out for emissions.

In contrast the open loop map is richer (for safety and power). It is preferred for performance because of that.

But all are effected by ambients.
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Re: The difference between closed loop & open loop fuel maps?
« Reply #3 on: June 17, 2014, 09:48:19 PM »
Peter Y is on the money. With lambda off, you run open loop all the time. The ECU still corrects based on air temp/pressure and engine temp.

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Re: Re: The difference between closed loop & open loop fuel maps?
« Reply #4 on: June 17, 2014, 10:45:47 PM »
Closed loop is, by definition, less static, because it takes the open loop map and adjusts it for real time O2 sensor feedback. And does so to lean it out for emissions.

In contrast the open loop map is richer (for safety and power). It is preferred for performance because of that.

But all are effected by ambients.
I'm wondering if it's the O2 sensor that gives the cold start issues??
 Or the cause of the surging??

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I'm wondering if it's the O2 sensor that gives the cold start issues??
 Or the cause of the surging??

In theory that's exactly the time it (the O2 sensor) wouldn't be working yet...
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Offline molly

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Re: The difference between closed loop & open loop fuel maps?
« Reply #6 on: June 18, 2014, 03:48:47 AM »
Switching off the lambda(s), going open loop only and adjusting the base map with Guzzidiag in most cases results in a better running motor. Of course getting the base map where you want it can take time, effort and money and some people might find it better left to the experts.  With the recent advent of map sharing the end result can be achieved more easily and a bit of fine tuning with a afr meter might be all that is required.
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Offline Wayne Orwig

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Re: Re: The difference between closed loop & open loop fuel maps?
« Reply #7 on: June 18, 2014, 07:36:39 AM »
I'm wondering if it's the O2 sensor that gives the cold start issues??

It takes a few minutes for the sensor to start working. The system is open loop when it is started. How would it do that?
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Re: The difference between closed loop & open loop fuel maps?
« Reply #8 on: June 18, 2014, 04:01:10 PM »
I see a lot good answers, happy to see people understand how it works. With most 5am guzzi maps, the maps are at the top half of the rev range to rich. That means the lambda is fighting the richness. And lambda is not always in closed loop. It's only doing that when you drive pretty constant. When accelerating you are not in closed loop.  Other side effect. The ecu has a long term accumulating setting if the lambda is to rich or lean. So if the lamdba has to do much leaning, that factor will be negative, and works as a modifier over the whole map. So also in the not to rich area's, the map is leaned out then. You can reset that value with reset autolearning parameters. It has two values, one for the idle range, one for the rest.
Paul

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Offline MLR

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Re: The difference between closed loop & open loop fuel maps?
« Reply #9 on: June 18, 2014, 07:21:46 PM »
Okay, looks like I was thinking of it a bit backwards. So ideally you you would want to leave the O2 sensors on and be able to alter the standard fuel mixture that they are trying to adjust to, but this value is set by the factory to meet emissions and is beyond our power to change.

Offline Arizona Wayne

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Re: The difference between closed loop & open loop fuel maps?
« Reply #10 on: June 19, 2014, 12:29:07 AM »
What about altitude changes?  Is that when the 02 sensor shows it's positive capabilities by adjusting the fuel/air mixture as needed for best efficiency?
« Last Edit: June 19, 2014, 12:31:00 AM by Arizona Wayne »

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Re: The difference between closed loop & open loop fuel maps?
« Reply #11 on: June 19, 2014, 01:03:56 AM »
What about altitude changes?  Is that when the 02 sensor shows it's positive capabilities by adjusting the fuel/air mixture as needed for best efficiency?

AFAIK, most EFI systems use an ambient Air Pressure/MAP (Manifold Air Pressure)/IAP (Intake Air Pressure) sensor or a MAF (Mass Airflow Sensor) to judge relative density of the air.

Now on MC EFI systems I believe it's not uncommon for that sensor to be integrated into the ECM and not mounted externally so it isn't found in the system breakdowns.

I don't see it listed on the 1TB V7 so either it's integrated, OR the mapping assumes sea-level and then compensates via 02 or ???
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Re: The difference between closed loop & open loop fuel maps?
« Reply #12 on: June 19, 2014, 04:25:16 AM »
for altitude is there an airpressure sensor and an table that adjusts  depending on pressure. Same with air and engine temperature.

indeed newer ecu have airpressure sensor inside. Guzzidiag shows airpressure so there is an sensor.
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Offline molly

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Re: The difference between closed loop & open loop fuel maps?
« Reply #13 on: June 19, 2014, 04:50:57 AM »
What Paul is saying is correct there are sensors for air temp and pressure on the 5AM ecu. Their readings are used in a table by the ecu to trim the main fuel table to allow for air density changes. You can alter this table with Guzzidiag if required, in my case to reduce the trimming in cold temperatures. This will still work with the lambda switched off.
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Offline mtiberio

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Re: The difference between closed loop & open loop fuel maps?
« Reply #14 on: June 19, 2014, 07:51:43 AM »
open loop fuel injection is like a blind person tossing a bucket of water towards someone shouting fire...

Offline Randown

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Re: The difference between closed loop & open loop fuel maps?
« Reply #15 on: June 19, 2014, 09:04:12 AM »
I see a lot good answers, happy to see people understand how it works.

With most 5am guzzi maps, the maps are at the top half of the rev range to rich.

That means the lambda is fighting the richness. And lambda is not always in closed loop.

It's only doing that when you drive pretty constant. When accelerating you are not in closed loop.  Other side effect.

The ecu has a long term accumulating setting if the lambda is to rich or lean. So if the lamdba has to do much leaning, that factor will be negative, and works as a modifier over the whole map.

So also in the not to rich area's, the map is leaned out then. You can reset that value with reset autolearning parameters. It has two values, one for the idle range, one for the rest.

Hi Paul, it just occurred to me the implications of what I think you're saying...it is possible that the bike you bought NEW & rode for miles may CHANGE its tuning potentially for the worse by virtue of the long term accumulating adjustment of the entire map...a Guzzi or any other brand for that matter may have a rich map section in the closed loop portion which the lambda corrects for, minusing down.

Over time the WHOLE map, open & closed loops can be minused down (made more lean) & create ride-ability, pinging & general lean AF problems where none existed before?



« Last Edit: June 19, 2014, 09:18:13 AM by Randown »
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Offline Randown

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Re: The difference between closed loop & open loop fuel maps?
« Reply #16 on: June 19, 2014, 09:14:26 AM »
open loop fuel injection is like a blind person tossing a bucket of water towards someone shouting fire...


Open loop is still waaay smarter than carbuerated...also it seems the lambda can "autotune" over fueling problems & cause the whole map to shift out of what's optimal.
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Re: The difference between closed loop & open loop fuel maps?
« Reply #17 on: June 19, 2014, 12:05:07 PM »
Open loop is still waaay smarter than carbuerated...also it seems the lambda can "autotune" over fueling problems & cause the whole map to shift out of what's optimal.

Correct, that could happen with closed loop. When the part you drive in most is rich, then the whole map will go down, leaning the part where you don't drive much but where it wasn't needed. With open loop this learning, that was made with good thoughts behind it, dioes not exist.

Lets be clear, I have nothing against a lambda sensor, but the ones used with the marelli ecu, are small band and slow. I have a wideband lambda on each bike. That one reacts real fast and has a wide range where the results are correct.
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Re:
« Reply #18 on: June 19, 2014, 02:01:25 PM »
On a Guzzi is the map a combo of open and closed? Yamaha does this. For throttle position is it roughly 0 - 40%, and rpms from about 0 - 6, 000. IIRC.

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Re:
« Reply #19 on: June 19, 2014, 02:53:37 PM »
On a Guzzi is the map a combo of open and closed? Yamaha does this. For throttle position is it roughly 0 - 40%, and rpms from about 0 - 6, 000. IIRC.

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 something like that, I don't know where it ends, and it only is closed at pretty steady rpms. Remember only for emision testing, not to make the thing run better or use less fuel.
« Last Edit: June 19, 2014, 02:54:34 PM by pauldaytona »
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Re: The difference between closed loop & open loop fuel maps?
« Reply #20 on: June 19, 2014, 04:24:22 PM »
+1 Paul.

You guys gotta realize, the narrowband lambda on Guzzis is for emissions purposes only, it is NOT to create a good ride.

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Re: Re: Re:
« Reply #21 on: June 19, 2014, 05:06:04 PM »
:):):)
something like that, I don't know where it ends, and it only is closed at pretty steady rpms. Remember only for emision testing, not to make the thing run better or use less fuel.
Thanks Paul.

The overly rich approach appears to be a industy norm these days.

I've done a fair amount of tuning with the AF1 guys and once a bike is open loop they tend to be pig, sloppy rich. With a good tune the bike runs smoother,  makes more power,  and gets better mileage.

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Offline bobdog6861

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Re: The difference between closed loop & open loop fuel maps?
« Reply #22 on: August 06, 2016, 12:46:34 AM »
It sounds like the closed loop on the V7 is really just for emissions compliance.  It must be better to run open loop only.  I presume that just unplugging the o2 sensors will lead to that.

beetle

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Re: The difference between closed loop & open loop fuel maps?
« Reply #23 on: August 06, 2016, 01:05:28 AM »
Er..no. That will give you a big red SERVICE warning. Or whatever the V7 'danger, Will Robinson' equivalent is.

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Re: The difference between closed loop & open loop fuel maps?
« Reply #24 on: August 06, 2016, 01:14:46 AM »
It'll throw up some sort of EFI/Engine Check light and I'd image throw it into some sort of 'Limp' mode. You can't just unplug sensors and not expect it to be recognised as a fault.

With the W5AM system a well built map can, in theory, be improved, by using a WB sensor input or a widget like a PC. While a laudable 'Holy Grail' I know from travelling with Mark that small issues can continue to raise their ugly heads. I'm willing to live with the 98% 'Close to perfection' of my open loop map and not deal with the headaches.

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Re: The difference between closed loop & open loop fuel maps?
« Reply #25 on: August 06, 2016, 03:37:39 AM »
open loop fuel injection is like a blind person tossing a bucket of water towards someone shouting fire...

If beetle's map for my 2V Norge is 'wrong', I don't wanna be right 'cause it runs and rides like a dream!

Word.

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Re: The difference between closed loop & open loop fuel maps?
« Reply #26 on: August 06, 2016, 04:07:54 AM »
Ignorami gonna ignore.

Offline jmac851

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Re: The difference between closed loop & open loop fuel maps?
« Reply #27 on: August 06, 2016, 05:14:19 PM »
Do you mean that I can just change my narrow band sensor to the wide band sensor without changing the original map?  What is the part number for the wide band sensor?
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beetle

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Re: The difference between closed loop & open loop fuel maps?
« Reply #28 on: August 06, 2016, 07:39:27 PM »
Do you mean that I can just change my narrow band sensor to the wide band sensor without changing the original map?  What is the part number for the wide band sensor?


Not that simple. The ECU will accept a wideband signal, but it will ignore signal values outside the narrowband range. You will need to get a wideband sensor and controller that can be programmed to emulate a narrowband signal, then program the wideband controller to the AFR values you want.

It's not plug 'n play. You'll also need a dummy resistor to fool the ECU into thinking it's still connected to the narrowband sensor because the ECU monitors the current draw. Otherwise you get an error, and limp mode in some cases. You also need twice the number of controllers and resistors etc. for 2- lambda bikes.

There's no 'part number'. It's all 3rd party stuff.


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Re: The difference between closed loop & open loop fuel maps?
« Reply #29 on: August 06, 2016, 08:08:07 PM »
It makes my tiny brain hurt just thinking about it. Thats why I'm more than happy to stick with the OL option. It just works.

Pete

 

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