DIYEFI.org Forum

Just a list of things I have been thinking off
Note I am not of educated experince on the ICE
1) load on a motor also is effected by time
2) I think\believe that there needs to be atleast the density factor and a seperate IAT compenstation table
I have seen so many ecu show they have the IAT compenstation table for density factor but it ends of being hijacked for altering fueling based on temp instead of using it only for density
3) I've realized that one can go into boost at stoichmetric but most cheap ecu's can't deal wtih it properly, most VE based ecu model commanded fuel with load as map or connected to the VE load. Its very annoying. As well as modeling the correction ign advance curve.
4) VE based ecu's and MAF based really require proper injector modeling. SD based seems to require accurate modeling of even more factors, Look at VW and their removal of MAF's now, tons of stuff is modeled in the ecu like egt, turbo speed, etc
5) torque based strategy with DBW implementation. This would require probably a good bit of work to implement but I could see it as a way to control the output better and usage for other things like power limiting\traction\etc
6) I somewhat question why you would have mutiple ve maps if ve is suppose be the engine's ability to breath. In the end I understand you can't model everything.

I have other ideas that eventually will come back into my head.
Most of my expereince is from a driveability standpoint and not much motorsports

1) load on a motor also is effected by time

How? Can you clarify this?

2) I think\believe that there needs to be atleast the density factor and a seperate IAT compenstation table
I have seen so many ecu show they have the IAT compenstation table for density factor but it ends of being hijacked for altering fueling based on temp instead of using it only for density

Sort of. My favourite ECU has open tables, but states in bold to set to scientificly known correction (ie the same as VE does). I still like having it visible and adjustable though.

3) I've realized that one can go into boost at stoichmetric but most cheap ecu's can't deal wtih it properly, most VE based ecu model commanded fuel with load as map or connected to the VE load. Its very annoying. As well as modeling the correction ign advance curve.

Just because you can doesn't mean you should. If you make less power than when running richer (and timing of course changed to suit) then you've proved that it isn't as efficient. If you can run richer and make more power, then why wouldn't you? Are you trying to cook everything? What do you mean "can't deal with it properly"?

4) VE based ecu's and MAF based really require proper injector modeling. SD based seems to require accurate modeling of even more factors, Look at VW and their removal of MAF's now, tons of stuff is modeled in the ecu like egt, turbo speed, etc

We used to manage. People are used to nicer more accurate things now though. Which is kind of why I'm a bit bewildered with VE model tuning on engines in which we don't know the exact flow rate of injectors or dead time tables, or OEM sensor calibrations - that exact info is also extremely helpful when using Injection Time tuning, though an exposed table lets you trim errors due to the sensor calibration being slightly out.
Basically, you need to do things properly, either model everything before fitting, or buy stuff that already has been.
Sounds expensive, for a DIY forum. So you could just run it a bit fat. Been working (?!) for Microtech all these years....

5) torque based strategy with DBW implementation. This would require probably a good bit of work to implement but I could see it as a way to control the output better and usage for other things like power limiting\traction\etc

Nice to have. You could limit throttle per gear or boost per gear, or throttle per %wheel slip or many other things far easier first.

6) I somewhat question why you would have mutiple ve maps if ve is suppose be the engine's ability to breath. In the end I understand you can't model everything.

Haven't used the software so can't comment on this, but have the same question now.

Most of my expereince is from a driveability standpoint and not much motorsports

Ah - That would be why you want to boost at stoich then. Just don't. OEM's would do it if it were feasible, for economy/emissions or whatever.
Lean isn't always more economical, as your power drops and you have to put your foot down to compensate. Mitsi GDI engines are a good (terrible) example of this. Tune to peak torque, and you'll have the best economy. If you have a lead foot that's your problem, don't punish your engine because of it.

Nige wrote:

6) I somewhat question why you would have mutiple ve maps if ve is suppose be the engine's ability to breath. In the end I understand you can't model everything.

Haven't used the software so can't comment on this, but have the same question now.

There are valid cases for multiple VE curves, and they mostly involve variable valve behaviour (timing and/or lift and/or duration). However, I have seen a variable compression engine. And there are plenty of engines with variable flaps for intake resonance. In all cases I'd prefer to have a tune for each state of such a device, and switch or blend between them once the right point was chosen from empirical data.

OEM's would do it if it were feasible, for economy/emissions or whatever.

Correction, OEMs *DO* do it. :-)

Also, he means in boost, not in full boost. Different concepts.

Tune to peak torque, and you'll have the best economy.

I'm not convinced that this is necessarily true... Best torque may require 20% more fuel than nearly best torque for less than 20% more torque, or whatever. For a given RPM/"load" point, there is a continuum of valid combinations, and exactly two of them are ideal. One delivers the maximum torque for the location, and the other produces the maximum efficiency for the location. They may coincide, but usually not.

Fred.

Nige wrote:

1) load on a motor also is effected by time

How? Can you clarify this?

Keep the load and rpms stready and watch temp rise over time period. As temps rises you get closer and closer to your knock threshold

Nige wrote:

2) I think\believe that there needs to be atleast the density factor and a seperate IAT compenstation table
I have seen so many ecu show they have the IAT compenstation table for density factor but it ends of being hijacked for altering fueling based on temp instead of using it only for density

Sort of. My favourite ECU has open tables, but states in bold to set to scientificly known correction (ie the same as VE does). I still like having it visible and adjustable though.

I'm talking using two different tables. one for only density and another to put fuel where you want it based on charge temp

Nige wrote:

3) I've realized that one can go into boost at stoichmetric but most cheap ecu's can't deal wtih it properly, most VE based ecu model commanded fuel with load as map or connected to the VE load. Its very annoying. As well as modeling the correction ign advance curve.

Just because you can doesn't mean you should. If you make less power than when running richer (and timing of course changed to suit) then you've proved that it isn't as efficient. If you can run richer and make more power, then why wouldn't you? Are you trying to cook everything? What do you mean "can't deal with it properly"?

4) VE based ecu's and MAF based really require proper injector modeling. SD based seems to require accurate modeling of even more factors, Look at VW and their removal of MAF's now, tons of stuff is modeled in the ecu like egt, turbo speed, etc

We used to manage. People are used to nicer more accurate things now though. Which is kind of why I'm a bit bewildered with VE model tuning on engines in which we don't know the exact flow rate of injectors or dead time tables, or OEM sensor calibrations - that exact info is also extremely helpful when using Injection Time tuning, though an exposed table lets you trim errors due to the sensor calibration being slightly out.
Basically, you need to do things properly, either model everything before fitting, or buy stuff that already has been.
Sounds expensive, for a DIY forum. So you could just run it a bit fat. Been working (?!) for Microtech all these years....

To start out with I started with a MS2, I really started in VE only to find out as time went on how much it takes for proper VE implementation.
One thing I have for that is injectors, ID1000's With a good bit of data ID has for them its great.

Nige wrote:

Most of my expereince is from a driveability standpoint and not much motorsports

Ah - That would be why you want to boost at stoich then. Just don't. OEM's would do it if it were feasible, for economy/emissions or whatever.
Lean isn't always more economical, as your power drops and you have to put your foot down to compensate. Mitsi GDI engines are a good (terrible) example of this. Tune to peak torque, and you'll have the best economy. If you have a lead foot that's your problem, don't punish your engine because of it.

[/quote]
OEM's do it. The chevy cruze won't go into PE till TPS is past 80%, the VW golf R runs WOT at stoichmetric until the modeled EGT hits the limit. Several oem vehicles don't go out of stoich in boost until around 4k revs or based on TPS.

Timing changes based on stuff like commanded lambda vs rpm
fuelign based on charge temp and rpm

eg cruze will be at .9 lambda if charge temp is near 0c, and closer to .75 at 40c

Fred wrote:

Nige wrote:

6) I somewhat question why you would have mutiple ve maps if ve is suppose be the engine's ability to breath. In the end I understand you can't model everything.

Haven't used the software so can't comment on this, but have the same question now.

There are valid cases for multiple VE curves, and they mostly involve variable valve behaviour (timing and/or lift and/or duration). However, I have seen a variable compression engine. And there are plenty of engines with variable flaps for intake resonance. In all cases I'd prefer to have a tune for each state of such a device, and switch or blend between them once the right point was chosen from empirical data.

Oh I understand if you change the VE of the motor you need that. I was talking more in the sense that people wanted to go from a race map to a track map using VE but with no VE changes from the motor and all they do is add more fuel in the VE table and nothing else, it seems to me you should be able to just have another commanded fuel table where you can use a variable selector to change from commanded fuel 1 to 2 or 3 based on what you need.

Fred wrote:

OEM's would do it if it were feasible, for economy/emissions or whatever.

Correction, OEMs *DO* do it.

Also, he means in boost, not in full boost. Different concepts.

Both to a point. VW seemed to figure out how long they can stay in stoichnmetric even at WOT till the exhaust gas temp rises to far.

Ah yeah, I guess you can if you monitor EGT etc. Fair enough - I'll concede that point.

VE tables for changes in cam/intake etc - yes, true.

For a given RPM/"load" point, there is a continuum of valid combinations, and exactly two of them are ideal. One delivers the maximum torque for the location, and the other produces the maximum efficiency for the location. They may coincide, but usually not.

True.

Keep the load and rpms stready and watch temp rise over time period. As temps rises you get closer and closer to your knock threshold

Wouldn't that be a temp correction then?

Nige wrote:

Keep the load and rpms stready and watch temp rise over time period. As temps rises you get closer and closer to your knock threshold

Wouldn't that be a temp correction then?

temp correction for density?
Thats only to keep the fueling the same accross the board
as the temp rises you need to reduce fuel because air is less dense, but at the same time as the temp rises and you keep your fuel the same say .88-.92 lambda in a N\A car and you keep your fuel the same you get closer and closer to det so either you have to increase fueling to help control combustion temp or reduce timing.
If you look at alot of standalone ecu's ( low end of the market ) they only have a correction table for supposed density factor, but people end up hijacking it and you end up seeing stuff like adding fuel above X temp. There is usually no other table for stuff like charge temp

I seen this in a corvette going around the track that I helped on, tune was around .9 lambda timing was good on dyno no knocking, made good power.
Come track it went around good couple laps go by and you saw knock sensors get more active as time went on. Still same load area, same ambt temp, stuff starts heating up in the engine bay. I don't care for what the person did to "fix" the issue but I wasn't around to offer my 2 cent at the time.

I'm curious what was logged to see what changed.

Just had a thought. Newer Ford Falcons run Cylinder head temp. Just a thought that may or may not help.
I have no idea if they run coolant temp as well, a friend happened to mention it in passing as he just bought one.

A quick note: air temp being high and engine temp being high both need some kind of anti knock strategy. For engine temp we have the other end of the warm up curve aptly named as "engine temp enrichment". No air temp effects available, yet.