Summary of Aftermarket ECUs / Controllers

[Whisky_Tango]

Originally Posted by Crufty Dusty

Eric,

Good effort, maybe make some minor amendments:

The ECU also goes into open loop mode when it detects a sensor has become faulty, when the engine is cold etc.

Ok, what kind of sensor? or any sensor tat is within the engine? Please elaborate... Thanks!

Originally Posted by Crufty Dusty

14.7 is lambda 1 for petrol engines only. Other fuels will have different stoichioimetric ratio.

Noted, will update in due course.

[Crufty Dusty]

Originally Posted by Whisky_Tango

Ok, what kind of sensor? or any sensor tat is within the engine? Please elaborate... Thanks!

For example, coolant temp... if the engine is "permanently cold", then the ECU will trigger a MIL and use a default coolant value. In the meantime it "knows" not to make use of the coolant sensor reading, thus it is in open loop. However you can't cheat the ECU and tune that out because the ECU will prevent that (like a "limp home" mode).

[The Mixmaster]

Fcuk! There are some serious petrolheads on BMWSG. I am so proud to be associated with these people.

[Shaun]

Real nice of you to spend your time creating the table, Eric.

Just to clarify, AFRs are by mass. Sometimes people think volume. Also, I don't think anyone should rely on the Magnuson-Moss warranty act unless they have the money and time to go through a drawn out legal process if the car company decides to be an ass.

[Crufty Dusty]

BTW... I have not come across any standalone ECU that has a "throttle map", "load map" etc. Perhaps some explanation is in order.

A map is nothing more than a table of values, kind of like an Excel spreadsheet.

Typically, if there is only 1 row, then it is called a table. If it has multiple rows, it is called a map. For this reason, a map is sometimes referred to as "3D", meaning it has multiple rows and columns. A "2D" table thus only has a single row. This is the basic distinction, although it is common for the terms to be used interchangeably especially in conversation.

Every ECU has at least 2 base maps: fuel and ignition. On each map, there are are rows and columns. The column values are in RPM, and the row values are whatever is determined to be load*. Where the rows and columns intersect, is called a load/RPM site. The ECU simply looks up these values in the fuel and ignition base maps very quickly to determine the proper amount of fuel/ignition timing to give the engine, in real time. Where there is no exact match in terms of load/RPM site, the ECU will use a combination of interpolation, statistics and history to arrive at an appropriate value.

Additionally, there are compensation maps such as coolant temp (cold start), acceleration/deceleration enrichment/enleanment, air temp, fuel temp, gear, so on and so forth.

* Depending on the ECU manufacturer, load can be based on MAF, MAP, MAP/EMAP, MAP/BAP, TPS etc or even a combination of the above.

[Crufty Dusty]

Everything else being equal, an ECU that has more load/RPM sites, allows the tuner to have better control over the engine operating parameters. Thus, when selecting an ECU, it is one point of consideration. Too many times enthusiasts have been led down the wrong path by observing what the race teams are using, e.g. "If this 900 bhp drag car is using XYZ ECU, it should work on my 250 bhp daily driver". They fail to understand that a drag car is always at WOT, and thus may not necessarily need high resolution maps.

So does having a 32x32 fuel and ignition map mean everything? Not necessarily. Unless the ECU allows you to customize the map area, it is nothing more than marketing talk. What do I mean? Say the ECU restricts you to 32 RPM sites, at 500 RPM intervals. That means it can control up to 16,000 RPM. Does your engine rev up to 16,000 RPM? It would be better if the ECU allows you to select a shorter interval between RPM points, say 250 RPM intervals. In this manner, you have finer resolution, allowing you greater control.

Another point of consideration is the number of I/O channels an ECU has. Using the earlier example, a drag car has no need for A/C, radiator fan control, idle control etc, so these may be lacking in the ECU as well. Since there is no need for these auxiliary functions, the ECU can omit them in the feature list, thereby reducing the cost.

These are just some basic points to take note of when selecting an aftermarket ECU. Be informed, and choose wisely. Have a clear goal of what you want to achieve with your car, and select an ECU that allows you to get there.

[Whisky_Tango]

[quote="Crufty Dusty"]

Originally Posted by Whisky_Tango

For example, coolant temp... if the engine is "permanently cold", then the ECU will trigger a MIL and use a default coolant value. In the meantime it "knows" not to make use of the coolant sensor reading, thus it is in open loop. However you can't cheat the ECU and tune that out because the ECU will prevent that (like a "limp home" mode).

Thanx Erik... I will include this in the "when it goes into open loop" section.

Maybe I will create a new heading for OBD II engine checks(MIL) lights.

[Whisky_Tango]

Originally Posted by Shaun

Real nice of you to spend your time creating the table, Eric.

Hey... no prob bro... and also thanx to you and Erik for your feedbacks and comments.

Originally Posted by Shaun

Just to clarify, AFRs are by mass. Sometimes people think volume.

Yes, air and fuel measured in mass. I will highlight this.

Originally Posted by Shaun

Also, I don't think anyone should rely on the Magnuson-Moss warranty act unless they have the money and time to go through a drawn out legal process if the car company decides to be an ass.

Tats true and besides its a foreign company which makes claims usually unsuccessful.
I will take this out.

[Whisky_Tango]

Originally Posted by Crufty Dusty

BTW... I have not come across any standalone ECU that has a "throttle map", "load map" etc.

Does this means piggyback ECU will not have Maps as well?

Originally Posted by Crufty Dusty

A map is nothing more than a table of values, kind of like an Excel spreadsheet.
Typically, if there is only 1 row, then it is called a table. If it has multiple rows, it is called a map. For this reason, a map is sometimes referred to as "3D", meaning it has multiple rows and columns. A "2D" table thus only has a single row. This is the basic distinction, although it is common for the terms to be used interchangeably especially in conversation.

Every ECU has at least 2 base maps: fuel and ignition. On each map, there are are rows and columns. The column values are in RPM, and the row values are whatever is determined to be load*. Where the rows and columns intersect, is called a load/RPM site. The ECU simply looks up these values in the fuel and ignition base maps very quickly to determine the proper amount of fuel/ignition timing to give the engine, in real time. Where there is no exact match in terms of load/RPM site, the ECU will use a combination of interpolation, statistics and history to arrive at an appropriate value.

Additionally, there are compensation maps such as coolant temp (cold start), acceleration/deceleration enrichment/enleanment, air temp, fuel temp, gear, so on and so forth.

* Depending on the ECU manufacturer, load can be based on MAF, MAP, MAP/EMAP, MAP/BAP, TPS etc or even a combination of the above.

Very informative! Will digest this and insert this into a new heading called "ECU Maps"

[Whisky_Tango]

Originally Posted by Crufty Dusty

Everything else being equal, an ECU that has more load/RPM sites, allows the tuner to have better control over the engine operating parameters. Thus, when selecting an ECU, it is one point of consideration. Too many times enthusiasts have been led down the wrong path by observing what the race teams are using, e.g. "If this 900 bhp drag car is using XYZ ECU, it should work on my 250 bhp daily driver". They fail to understand that a drag car is always at WOT, and thus may not necessarily need high resolution maps.

So does having a 32x32 fuel and ignition map mean everything? Not necessarily. Unless the ECU allows you to customize the map area, it is nothing more than marketing talk. What do I mean? Say the ECU restricts you to 32 RPM sites, at 500 RPM intervals. That means it can control up to 16,000 RPM. Does your engine rev up to 16,000 RPM? It would be better if the ECU allows you to select a shorter interval between RPM points, say 250 RPM intervals. In this manner, you have finer resolution, allowing you greater control.

Another point of consideration is the number of I/O channels an ECU has. Using the earlier example, a drag car has no need for A/C, radiator fan control, idle control etc, so these may be lacking in the ECU as well. Since there is no need for these auxiliary functions, the ECU can omit them in the feature list, thereby reducing the cost.

These are just some basic points to take note of when selecting an aftermarket ECU. Be informed, and choose wisely. Have a clear goal of what you want to achieve with your car, and select an ECU that allows you to get there.

Thanx for more info!

So generally, high resolution maps are for passenger car & race cars (not the hardcore or F1) and low resolution maps are for drag cars.

Any other features or benefits of standalone ECU and hope u can share some of the reliable ones for OBD II system. Thanks